Heme Flashcards

Question

Monocytes develop in the bone marrow from myelomonocytic progenitor cells (CFU-GM) under the influence of the cytokines M-CSF and GM-CSF. Mature monocytes are released from the bone marrow into the circulation where they circulate with a half-life of ___ days before entering tissues and body fluids in response to inflammation and infection. Within tissues, monocytes may further differentiate into a variety of cell types (depending on the cytokine milieu), including ___. In body fluids, monocytes may differentiate into ___.

Answer 1

Monocytes develop in the bone marrow from myelomonocytic progenitor cells (CFU-GM) under the influence of the cytokines M-CSF and GM-CSF. Mature monocytes are released from the bone marrow into the circulation where they circulate with a half-life of 2 to 3 days before entering tissues and body fluids in response to inflammation and infection. Within tissues, monocytes may further differentiate into a variety of cell types (depending on the cytokine milieu), including macrophages, tissue histiocytes, dendritic cells, skin Langerhans cells, liver Kupffer cells, splenic macrophages, alveolar macrophages, multinucleated giant cells, CNS microglial cells, and bone osteoclasts. In body fluids, monocytes may differentiate into serous macrophages, type A synovial cells, and multinucleated giant cells.

Answer 2

Cytoplasmic plasma cell inclusions, representing aggregates of immunoglobulins synthesized by the cell. They are homogenous hyaline eosinophilic globules 4-5 micrometers in diameter. Can be seen in plasma cells in multiple myeloma or chronic inflammatory exudates.

Answer 3

Normal K:L is 2-3:1, but monoclonality should not even be considered until the ratio is at least 8-10:1. A reverse K:L in whish L>K is abnormal; be highly suspicious of monoclonality with a reverse K:L > 2:1. Normal CD4:CD8 is 2:1, but may be as high as 20-30:1 and still be considered nonspecific. T-cell monoclonality is suggested by loss of a pan-T-cell associated antigen, usually CD7 first, followed by CD5, CD2, and then CD3. Co-expression of both CD4 and CD8, or dual negative T-cells is aberrant, and suggests a lymphoproliferative process. Peripheral blood B-cell:T-cell lymphocyte ratio is ~1:4; lymph node B-cell:T-cell lymphocyte ratio is ~4:1.

Answer 4

CD16, CD56, CD57.

Answer 5

CD11c and CD103.

Answer 6

MCV = Hct x 1000 / RBC. MCHC = Hb / Hct x 100. Hct = MCV x RBC.

Answer 7

ARC = % retics x RBC. CRC = % retics x Hct / 45. The CRC takes into account spuriously increased reticulocyte percentages due to a low Hct. RPI = CRC x 1 / correction factor. The RPI reflects the fact that in anemia, reticulocytes are released earlier from the marrow and therefore have a longer maturation time than normal to mature into red cells. The correction factor is 1.0 when the Hct is normal, 2.0 when Hct is 30, and 3.0 when Hct is 15.

Answer 8

Most commonly, hemoglobin is measured by the cyanohemoglobin (hemiglobin cyanide) method, in which hemoglobin is converted to hemiglobin cyanide (HiCN), whose concentration is measured by spectrophotometry. To carry out this conversion, blood is dissolved in a solution of potassium ferricyanide and potassium cyanide which oxidizes the hemoglobin to hemiglobin (Hi; methemoglobin) and then converts it to hemiglobin cyanide (HiCN). The solutions' absorbance at 540 nm reflects the amount of hemoglobin originally present. This methods detects all forms of hemoglobin (Hb, HbO2, Hi, HbCO) except sulfhemoglobin (SHb).

Answer 9

QLs are collections of inflammatory cells usually found along the endocardium, but sometimes extending deeper into tissues, that can mimic acute rejection. QLs are also known as endocardial infiltrates and have been the subject of more than a dozen different studies, and there is still no consensus as to their etiology or significance. They have been associated with the use of cyclosporine and waxing and waning levels of immunosuppression. It has also been suggested that QLs represent a "benign" form of rejection, or an analogue of vascular rejection. More recent studies in experimental animals suggest that they may be sites of antigen processing and low grade immune stimulation. In human and experimental animals, QLs are comprised predominantly of T cells, with the CD4 subset predominating over CD8 cells by a ratio of 2-3:1. QLs have been subclassified on the basis of whether they infiltrate the underlying myocardium. In type A lesions, the border with the underlying myocardium is smooth. In type B lesions, the mononuclear cells infiltrate between myocytes in the underlying myocardium, but myocyte necrosis is not seen. On a practical level, QLs are generally not considered in the grading of cardiac allograft rejection, but mentioned in the diagnosis as a separate finding.

Answer 10

Membranoproliferative glomerulonephritis is a well-known manifestation of hepatitis C. In the setting of malignancies, MPGN is often associated with non-Hodgkin lymphoma, and is less common observed with solid tumors.

Answer 11

MCH is derived from the ratio of total hemoglobin expressed as g/L and the erythrocyte count expressed as x 10^12/L, the results are presented in picograms (10^-12 g). Therefore, MCH provides an absolute gravimetric measurement of the hemoglobin in the average erythrocyte. MCHC, however, provides the ratio of the hemoglobin to the volume of the average cell. MCHC is useful in many conditions, such as normochromic normocytic anemias, where the amount of hemoglobin produced parallels changes in the MCV. However, when evaluating conditions with a decreased eruthrocyte volume, such as thalassemia or iron deficiency, or increased absolute erythrocyte hemoglobin such as hemochromatosis, changes in erythrocyte volumes create problems in interpretation if the MCV or MCHC are used. For example, as erythocytes age, the MCV will increase and consequently the MCHC will decrease, yet the absolute amount of MCH does not change. Such constancy of the MCH is why decreased MCH is used as a tool for evaluating possible thalassemia, iron deficiency, or hemochromatosis.

Answer 12

In the majority of cases with hematolymphoid processes, the spleen will be involved in one of three patterns: predominately white pulp involvement, a predominately nodular pattern irrespective of white or red pulp, and predominately red pulp involvement. Most of the small B-cell lymphomas, including chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), follicular lymphoma, mantle cell lymphoma (MCL), splenic marginal zone lymphoma (SMZL), and lymphoplasmacytic lymphoma classically involve the white pulp with or without extension into the red pulp. Large cell lymphoma and Hodgkin lymphoma typically have a random, nodular pattern. Predominantly red pulp diseases include hairy cell leukemia (HCL), large granular lymphocytic leukemia, and myeloproliferative disorders, such as chronic myelogenous leukemia and chronic idiopathic myelofibrosis.

Answer 13

The plasma cell variant of Castleman's disease comprises 10-20% of unicentric cases of Castleman's disease and usually presents in the 6th decade of life. It is sometimes associated with system symptoms (fever, night sweats, and weight loss) and laboratory abnormalities, including increased serum IL-6 which is thought to originate from affected lymph nodes and be responsible for the systemic manifestations of the disease.

Answer 14

HHV8-negative plasma cell variant of CD is characterized by large sheets of mature plasma cells expanding interfollicular regions. While plasma cells are usually polyclonal, a subset of cases shows monoclonal plasma cells; these plasma cells are usually lambda light chain restricted. A subset of follicles may have hyaline vascular-like features; though, these features are often less distinct than in hyaline vascular CD. The HHV8-positive plasma cell variant of CD has interfollicular areas expanded by large sheets of mature, immature, and/or atypical plasma cells. These cases can have increased numbers of plasmablasts in the follicle mantle zones, and a subset of them evolves into HHV8-positive plasmablastic lymphoma.

Answer 15

Almost all cases of mantle cell lymphoma have a balanced chromosomal translocation between IgH and CCND1 (cyclin D1), t(11;14)(q13;q32).

Answer 16

It typically presents in the second portion of the duodenum, and less frequently, in the jejunum. It appears endoscopically as one or more small polyps. Although typically asymptomatic, it may present with bowel obstruction. Staging must be performed to exclude GI involvement by a more widespread follicular lymphoma, such as one involving retroperitoneal lymph nodes. Patients with confirmed primary intestinal follicular lymphoma seem to have excellent survival and may not require treatment.

Answer 17

Plasmacytic differentiation in MALT lymphoma is fairly common, seen to some extent in ~1/3 of MALT lymphoma cases. Occasionally, plasma cells are the predominant cell type, potentially leading to confusion with other hematolymphoid neoplasms, such as plasmacytoma and lymphoplasmacytic lymphoma. Thus, MALT lymphoma with plasmacytic differentiation should be considered in the differential diagnosis of any plasmacytic lesion, particularly in the setting of a disease site or clinical senario that would be unusual for a plasmacytoma, such as a very young patient.

Answer 18

ImmunoProliferative Small Intestinal Disease is a rare disorder that is considered a variant of MALT lymphoma with nearly complete plasmacytic differentiation. Its name results from its preferential involvement of the small intestine, but it is also known as IgA heavy chain disease, because the neoplastic cells in about one-half of cases produce an abnormal, truncated IgA heavy chain that is missing the variable and the first constant regions and that can be found in the serum. The plasma cells will be positive for CD138 but negative for kappa and lambda light chains. IPSID is suspected to result from Campylobacter infection, and early cases have a relatively high rate of response to broad-spectrum antibiotics. Although it was thought that IPSID was entirely an inflammatory process, it has been now confirmed as a clonal process. It is relatively common for IPSID to progress to a high-grade lymphoma indistinguishable from DLBCL.

Answer 19

Morphologically, they consist of sheets of medium-sized transformed lymphocytes with minimal pleomorphism, multiple nucleoli, and numerous admixed tingible-body macrophages. Immunophenotypically, they are CD20-positive B-cells that co-express CD10, BCL6, and CD43. They are typically negative for BCL2. Ki-67 is nearly 100%. There are very few admixed T-cells. On cytogenetic studies, >90% of cases show a translocation involving the MYC gene on chromosome 8. Most cases have the MYC gene juxtaposed with the IGH gene on chromosome 14, while a minority involves the kappa (chromosome 2) and lambda (chromosome 22) light chain genes.

Answer 20

Dense proliferations of lymphocytes in the lung, forming a mass lesion, should be ruled out for lymphoma. With this in mind, areas of lymphoid hyperplasia can form a localized or multinodular mass in lung. The inciting trigger for lymphoid hyperplasia has been proposed to be a foreign body/foreign antigen, and this can sometimes be demonstrated. These proliferations are composed of well formed follicles with organized B-cell and T-cell zones without invasion of pleura or bronchus. Involvement of epithelium can be present, mimicking a lymphoepithelial lesion, but in contrast to B-cell lymphoma, the infiltrating cells are T cells. The plasma cells within the lesion can have Russell bodies but not Dutcher bodies.

Answer 21

INR = [Patient PT / Mean of normal PT range] ^ ISI. ISI = International Sensitivity Index for thromboplastin, used for PT determination. A patient with high ISI (ISI = ~2) will have low sensitivity to factor deficiencies. A patient with low ISI (ISI = ~1) will have high sensitivity to factor deficiencies.

Answer 22

The Greek word "pelios" means "discoloured by extravasated blood," or "livid". Peliosis is a pathological entity characterized by the gross appearance of multiple cyst-like, blood-filled cavities within parenchymatous organs. The classical pathoanatomical concept is based upon the opinion that peliosis exclusively develops in organs belonging to the mononuclear phagocytic system (liver, spleen, bone marrow, and lymph nodes). However, a paucity of studies indicates that other organs such as lungs, parathyroid glands, and kidneys may be affected too. Since the disease may culminate in spontaneous rupture of the affected organ and thus may mimic a violent death at autopsy, peliosis is far more than just another morphological curiosity.

Answer 23

Peliosis hepatis is characterised by randomly distributed multiple blood-filled cavities throughout the liver. The size of the cavities usually ranges between a few millimeters to 3 cm in diameter. The pathogenesis of peliosis hepatis is unknown. There are several hypotheses as to cause: it arises from sinusoidal epithelial damage, from increased sinusoidal pressure due to obstruction in blood outflow from the liver, or from hepatocellular necrosis. The condition is typically asymptomatic and is discovered following evaluation of abnormal liver function tests. However, when severe it can manifest as jaundice, hepatomegaly, liver failure and hemoperitoneum. Disease associations include… Infections: HIV, Bacillary peliosis (caused by Bartonella), Staphylococcus aureus. Chronic conditions: End stage renal failure, Kwashiorkor, tuberculosis and other chronic infections. Malignancy: Monoclonal gammopathies, Hodgkin disease, malignant histiocytosis, seminoma, hepatocellular adenoma, hepatocellular carcinoma. Renal transplants: It can be found in up to 20% patients, can be related to azathioprine or cyclosporine use, and may be associated with increased risk of transplant rejection. Drugs and toxins: Corticosteroids, androgens, azathioprine, tamoxifen.

Answer 24

Allergic reactions (drug reactions, asthma), parasitic infections (strongyloidiasis), schistosomiasis, filariasis, toxocariasis), metabolic abnormalities (adrenal insufficiency), humoral immunodeficiency (hyperimmunoglobulin E syndrome (Job syndrome), Wiskott-Aldrich syndrome, hyperimmunoglobulin M syndrome, immunoglobulin A deficiency), pulmonary eosinophilias (eosinophilic granulomatosis with polyangiitis (formerly Churg-Strauss syndrome), allergic bronchopulmonary aspergillosis, chronic and acute idiopathic eosinophilic pneumonias), autoimmune blistering skin diseases (dermatitis herpetiformis, bullous pemphigoid).

Answer 25

Reactive eosinophilia is frequently observed in patients with lymphoma, often because of increased production of growth factors by the malignant cell population. In Hodgkin lymphoma, the reported incidence of blood eosinophilia is 15%. Bone marrow and tissue eosinophilia are also common, although surprisingly, there is no strong correlation with peripheral eosinophil counts. The incidence of tissue eosinophilia varies between types of Hodgkin lymphoma and is most common in the mixed cellularity form and the nodular sclerosing form of the disease. As with many reactive eosinophilias, the mechanism appears dependent on increased IL-5 levels, and possibly IgE levels, both which may be produced directly by Reed-Sternberg cells.

Answer 26

Eosinophilia may be associated with a variety of B-cell and T-cell neoplasms. B-cell lymphoblastic leukemia (BLL) with eosinophilia is one such example. It is often associated with a characteristic cytogenetic abnormality t(5;14), which juxtaposes the IL3 gene on chromosome 5 to the immunoglobulin heavy chain locus (IgH) on chromosome 14. These cases are recognized in the 2008 WHO classification as B lymphoblastic leukemia with t(5;14); IL3-IgH.” This rearrangement implies a “reactive” eosinophilia, in which increased IL-3 expression by malignant, lymphoblastic clones provides a paracrine signal, driving polyclonal expansion of the eosinophils.

Answer 27

Myeloid sarcoma is an extramedullary tumor mass of neoplastic immature myeloid (granulocytic or monocytic) cells, and is also called extramedullary myeloid tumor, granulocytic sarcoma, or chloroma.

Answer 28

Lymphangioleiomyomatosis (or lymphangiomyomatosis) (LAM) occurs almost exclusively in reproductive age women and consists of a proliferation of immature myoid cells which are currently thought to derive from perivascular epitheliod cells (PEC). LAM may involve the lungs and axial thoraco-abdominal lymphatic system including both lymph nodes and the thoracic duct. Supraclavicular and inguinal nodes may rarely be involved. In most cases, the pulmonary manifestations dominate but LAM may occasionally present exclusively in the abdomen. Abdominal LAM may mimic ovarian carcinoma radiographically and patients may present with pain, often due to hemorrhage. LAM may occur in association with tuberous sclerosis (TS) or in isolation (sporadic LAM), although in either form the LAM cells may be associated with mutations of the TS genes, TSC-1 or TSC-2. Whether LAM is sporadic or associated with TS, the histologic appearance is the same but lymph node involvement is more frequent in patients without TS.

Answer 29

Absolute contraindications: TTP and HIT. Immune thrombocytopenia (idiopathic thrombocytopenic purpura and post-transfusion purpura) are strong relative contraindications; Do not transfuse unless severe thrombocytopenia with life-threatening bleeding; Large numbers of units may be needed due to rapid immune destruction.

Answer 30

KL is a self-limiting non-neoplastic lymphadenopathy described originally in Asian countries (particularly China, Japan, and Indonesia) but also seen sporadically in Caucasians. KL presents classically in the head and neck region, involving deep soft tissues and local lymph nodes, predominantly of young adults. The age range is typically 27-40 and males are more often affected than females (3:1). No infectious agents have been demonstrated.

Answer 31

ALHE can have a striking histologic similarity to KL. ALHE is present mostly in Caucasians and can be confused with early stage KL. ALHE more often affects females and is seen in soft tissues and superficial dermis forming clusters of eosinophilic cells. ALHE typically presents as cutaneous papules rather than a mass lesion, and histology reveals non-nodal collections of eosinophils with hypertrophic endothelial cells that protrude and occlude vascular lumina in a tombstone pattern. Lymphadenopathy, which is an essential feature in KL, is not frequently seen in ALHE.

Answer 32

Mantle cell lymphoma represents between 2.5% and 10% of all non-Hodgkin lymphomas, and the tumor more commonly affects male patients, with most presenting with advanced disease, having bone marrow involvement at the time of diagnosis.

Answer 33

FISH studies for cyclin D1 are very important in making a definitive diagnosis of MCL. Translocation t(11;14)(q13;q32) is the chromosomal rearrangement juxtaposing the cyclin D1 gene locus (CCND1) on chromosome 11q13 with the immunoglobulin heavy chain locus (IGH) located on chromosome 14q32, placing CCND1 under control of IGH enhancer sequences, and leading to over-expression of cyclin D1 protein. In addition to cyclin D1 immunoreactivity, MCL tumor cells are positive for pan-B-cell markers, CD19 and CD20. Surface immunoglobulin and IgM are also positive, with or without associated IgD positivity. Tumor cells also show CD5 immunoreactivity, and are negative or only weakly positive for CD23, a marker helpful in distinguishing between chronic lymphocytic leukemia/small lymphocytic lymphoma, which is typically positive for CD23.

Answer 34

The first pattern is characterized by an abnormal architecture composed of back-to-back follicles separated by scant red pulp. In the second pattern, the splenic architecture is relatively intact with scattered neoplastic follicles primarily involving the white pulp. This pattern must be discriminated from reactive follicular hyperplasia.

Answer 35

MALT lymphoma is the most common primary pulmonary lymphoma, comprising up to 70% of all cases. MALT lymphomas may have a deceptively heterogenous appearance microscopically, including germinal center formation and a mixture of T-cells and B-cells by IHC.

Answer 36

The primary entity in the differential diagnosis of pulmonary MALT lymphoma is nodular lymphoid hyperplasia (NLH). Such lesions are extremely rare. The most important caveat is that any mass-forming lesion effacing the underlying lung architecture should be considered a lymphoma until proven otherwise, so careful exclusion of lymphoma is of paramount importance before rendering a diagnosis of NLH.

Answer 37

Typically, NLH presents as solitary peripheral nodules but may be multiple on occasion. NLH is well-circumscribed in comparison to MALT lymphoma, and lacks peripheral lymphangitic spread of the lymphoproliferative process. Additionally, lymphoepithelial lesions should be absent or very rare in NLH, and plaque-like infiltration of the pleura and Dutcher bodies should not be seen. Germinal center formation may be quite pronounced and plasma cells are prominent between the reactive follicles. Immunostains show a distribution of B- and T-cells typical of reactive follicles and the plasma cells lack light chain restriction. Similarly, no evidence of clonality should be evident by flow cytometry or molecular studies.

Answer 38

LYG is an angiocentric lymphoproliferative disorder which may involve multiple organs, but frequently involves the lungs. LYG is comprised of a mixture of neoplastic, large, morphologically atypical B-cells admixed with variable numbers of background T-cells. LYG is traditionally divided into three grades (LYG 1, 2, and 3) depending on the percentage of each cell type present, with LYG grade 3 being comprised essentially entirely of large B-cells and generally regarded as a B-cell lymphoma. Grade 1 LYG, however, is comprised primarily of small background T-cells and only a small percentage of large atypical B-cells, and therefore may be considered in the differential of MALT lymphoma. LYG occurs most commonly in immunocompromised individuals and typically presents as multiple masses, often with cavitation.

Answer 39

Morphologically, LYG is angiocentric and may show large zones of necrosis with preservation of viable cells around blood vessels, although necrosis may not be as prevalent in cases of grade 1 LYG. While on initial evaluation the lesion may appear to be a mixture of T- and B- lymphocytes, careful inspection will reveal the atypical morphology of the B-cells. Additionally, LYG is an EBV driven process and the neoplastic B-cells will be positive for EBV latent membrane protein in most cases.

Answer 40

EBV. LYG is an EBV driven process and the neoplastic B-cells will be positive for EBV latent membrane protein in most cases.

Answer 41

Histopathological diagnosis of myelolipoma involves demonstration of (a) lipomatous compartment, which is composed of mature adipocytes and (b) hematopoietic compartment, which includes any of the three lineages (myeloid, erythroid, and megakaryocytic). An exclusively lymphocytic, monocytic or histiocytic cell infiltration will not constitute the myeloid (marrow) compartment's equivalence. In addition, caution should be exercised in tumors that show only mature myeloid cells (granulocytes, or eosinophils); granulocytic cells can be part of the inflammatory infiltrate within a lipoma, and do not constitute a true myeloid compartment. Similarly, immature myeloid cells, such as blasts, can be present in soft tissue involvement by leukemia (myeloid sarcoma), and hence should be interpreted with caution. Unequivocal proof of myeloid (marrow) compartment of myelolipoma is provided by the presence of erythroid colonies and/or megakaryocytic cells.

Answer 42

Salivary gland enlargement associated with a significant lymphoid infiltrate is recognized in HIV-positive patients. Because the lymphoid tissue usually exhibits morphologic and immunophenotypic features similar to those seen in florid follicular hyperplasia and the lesions often occur in association with enlarged lymph nodes, benign lymphoepithelial cystic lesions are thought to represent a manifestation of persistent, generalized lymphadenopathy. AKA benign lymphoepithelial lesion, benign lymphocpithelial cyst, cystic lymphoid hyperplasia, and HIV-related salivary gland disease. The lesion most commonly arises in the parotid gland where it occurs in 3-6% of adults and 1-10% of children with HIV. Overall, benign lymphoepithelial cystic lesions account for ~25% of enlarged salivary glands in the HIV positive patient population. The lesions are often cystic, bilateral, multiple, and associated with lymphadenopathy. Morphologically, they are characterized by epithelial-lined cysts, often with squamous metaplasia, follicular hyperplasia, glandular atrophy, and in some cases epimyoepithelial islands. In many patients, treatment with HAART results in smaller lesions or their complete resolution.

Answer 43

The risk of developing lymphoma for patients with HIV-related multicentric Castleman Disease is ~15x higher than it is for the general HIV-positive patient population. The survival of patients with HIV MCD who develop lymphoma is poor.

Answer 44

The incidence of non-Hodgkin lymphoma in HIV+ individuals is ~70 to 80x greater than that of the general population.

Answer 45

Although not considered an AIDS-defining illness, HIV+ individuals have a 5 to 15x greater risk of developing cHL than immunocompetent patients. The incidence of HIV cHL has increased with the advent of HAART. Furthermore, the relative risk of developing cHL is higher in patients on HAART than it is in those who are not.

Answer 46

The HIV-related plasmablastic lymphomas characteristically arise in the oral cavity (60% of cases); however, they can also occur in other mucosal sites, such as the sinonasal cavity and the GI tract, and in nonmucosal sites, such as the skin, soft tissue, and lymph nodes.

Answer 47

Progressive HIV-related lymphadenopathy/HIV-related benign lymphadenopathy. Benign lymphoepithelial cystic lesions. Multicentric Castleman disease. Lymphomas associated with HIV can be subcategorized as those occuring (1) also in immunocompetent patients (most cases), (2) more specifically in HIV+ patients (~5% of cases), and (3) in other immunodeficiency states (<5% of cases). The main entities in (1) are BL (~30% of HIV-related lymphomas), DLBCL (~40%), and cHL (~5-15%). These neoplastic entities account for most of the HIV-related lymphoma, although only the first 2 entities are AIDS-defining diseases. The neoplasms in (2) are highly associated with infection by EBV, KSHV/HHV8, or both. They include: Plasmablastic lymphoma. KSHV+/HHV8+ large B-cell lymphoma associated with MCD. Primary effusion lymphoma/Extracavitary primary effusion lymphoma. In (3), the HIV polymorphic lymphoid proliferations, which resemble the polymorphic poasttransplant-associated lymphoproliferative disorders seen in solid organ transplant recipients, comprise thie category of HIV-related lymphoma/lymphoma-like lymphoproliferative disorders.

Answer 48

Primary pulmonary lymphoma can be diagnosed when there is a clonal lymphoid proliferation affecting one or both lungs (parenchyma and/or bronchi) without evidence of mediastinal lymphadenopathy or a mass on chest imaging in a patient with no previous extrathoracic involvement at the time of diagnosis or during the subsequent 3 months. Primary lymphoma of the lung is a rare disorder and represents only 0.3% of all primary pulmonary malignancies, <1% of all the cases of non-Hodgkin lymphoma, and 3-4% of all the extranodal manifestations of non-Hodgkin lymphoma.

Answer 49

Polymorphic and monomorphic. Polymorphic PTLD is characterized morphologically by a plethora of monoclonal B cells in all stages of maturation as well as reactive T cells. Monomorphic PTLD is a subtype of non-Hodgkin lymphoma that appears as homogeneous sheets of transformed, monoclonal B cells, often with cytogenetic abnormalities. Regardless of the histologic features, the lymphoid cells in most cases of PTLD contain EBV detected by IHC or ISH.

Answer 50

It is a rare EBV-positive DLBCL arising in patients with long-standing chronic pyothorax (treated with iatrogenic pneumothorax), secondary to tuberculosis. Patients present with a mass in the pleura accompanied rarely by lung mass or pleural effusion. On microscopic examination, the tumor shows diffuse proliferation of large atypical cells, with centroblastic and/or immunoblastic or plasmacytoid features with areas of necrosis. Neoplastic cells express pan-B-cell antigens and MUM1; rarely are CD138 positive; and are negative for CD10, bcl-6, and HHV-8. These patients have a dismal prognosis.

Answer 51

Isolated lymphopenia is uncommon but may be seen in SLE, HIV, SARS, anti-CD20 (rituxan) therapy, steroid therapy, and certain congenital immunodeficiencies (Bruton, SCID, DiGeorge, CVI).

Answer 52

With an isolated monocytopenia, consider hairy cell leukemia or steroid therapy. In patients undergoing chemotherapy, monocytopenia heralds the onset of neutropenia.

Answer 53

Follicular pattern. Interfollicular pattern. Sinus pattern. Diffuse pattern.

Answer 54

In RFH, the germinal centers usually remain separate and vary in size (but they may coalesce in some cases). The germinal centers contain numerous mitoses and tingible-body macrophages. Staining with bcl-2 is weak or absent within the germinal center (but strong in the surrounding mantle), while PCNA (Ki-67, proliferating cell nuclear antigen) is strongly expressed. In follicular lymphoma, follicles are often "naked" (mantles are obliterated) and confluent. Mitoses and tingible-body macrophages are rare. Staining with bcl-2 is strong in the follicle, and PCNA is weak.

Answer 55

Nonspecific reactive follicular hyperplasia (etiology unknown) is the most common scenario. HIV infection produces a profound variety called florid follicular hyperplasia. RA and Sjogren syndrome produce RFH, frequently with interfollicular plasmacytosis. Syphilis also produces a RFH with interfollicular plasmacytosis, but also causes capsular and trabecular thickening (due to chronicity) and capsular infiltration by plasma cells. Castleman disease.

Answer 56

Viral infections such as infectious mononucleosis, CMV, and postvaccinial lymphadenitis. Hypersensitivity reactions, such as from dilantin. Kimura disease.

Answer 57

Sinus histiocytosis, a nonspecific reaction to numerous lymph node stimuli. Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease). Lymphangiogram effect. Whipple disease. Hemophagocytic syndrome. Dermatopathic lymphadenitis.

Answer 58

The diffuse pattern of nodal expansion, easy to confuse with lymphoma, is produced by several viruses, particularly EBV, but also CMV, HSV, measles, or post-vaccinia lymphadenitis.

Answer 59

Deletion of 13q14 (>50% of cases). Other frequent findings are trisomy 12 (15-20%), del(11q), del(14q), and del(17p).

Answer 60

Nodular, interstitial, and diffuse. The nodular and interstitial patterns correlate with a better prognosis, while diffuse a pattern correlates with a worse prognosis.

Answer 61

Bright CD20, bright sIg, CD38 expression, and ZAP-70 expression. ZAP-70 is the Z-chain-associated protein-70, a tyrosine kinase normally associated with the T-cell receptor (TCR) Z chain.

Answer 62

A subset of mantle cell lymphoma (MCL) with a tendency for peripheral blood involvement tend to have cytogenetic aberrations involving 8, 17, and 21 (in addition to the requisite t(11;14)).

Answer 63

They are a family of retrovirus-associated DNA sequences (myc) originally isolated from an avian myelocytomatosis virus (myc for MYeloCytomatosis). The proto-oncogene myc (c-myc) codes for a nuclear protein which is involved in nucleic acid metabolism and in mediating the cellular response to growth factors. Truncation of the first exon, which appears to regulate c-myc expression, is crucial for tumorigenicity. The human c-myc gene is located at 8q24.

Answer 64

Central diabetes insipidus (DI) is the most frequent CNS manifestation of LCH, occurring in approximately 25% of pts. Multisystem LCH and craniofacial bone lesions with associated soft tissue masses are the 2 most important risk factors for the development of DI in patients with LCH.

Answer 65

Evans syndrome is an autoimmune disease in which an individual's antibodies attack their own RBCs and platelets. Both of these events may occur simultaneously or one may follow on from the other. Its overall pathology resembles a combination of autoimmune hemolytic anemia and ITP. The diagnosis is made upon blood tests to confirm not only hemolytic anemia and idiopathic thrombocytopenic purpura, but also a positive DAT and an absence of any known underlying etiology. Other antibodies may occur directed against neutrophils and lymphocytes, and "immunopancytopenia" has been suggested as a better term for this syndrome. Initial treatment is with glucocorticoid corticosteroids or IVIg, a procedure that is also used in ITP cases. Although the majority of cases initially respond well to treatment, relapses are not uncommon and immunosuppressive drugs are subsequently used. Splenectomy is effective in some cases, but relapses are not uncommon. The only prospect for a permanent cure is allogeneic HSCT.

Answer 66

Lymphoma with artifactual signet ring cells due to cytoplasmic shrinkage (CD45 is usually positive in lymphoma). Metastases from breast or lung (clinical history, plus the use of appropriate immunostains such as TTF1 or GCDFP-15 is helpful). Reactive epithelial atypia associated with radiation treatment or chemotherapy. Xanthoma.

Answer 67

0-12 hours: Parenchymal hemorrhages. 12-48 hours: "Macrophages" (refers to the "starry sky" appearance in the cortex) in cortex. 48-72 hours: "Macrophages" with "mulberries" (refers to small clusters of lymphocytes) in cortex, cellularity of cortex begins to diminish. 3-7 days: Corticomedullary distinction lost with increasing prominence of Hassall corpuscles. 7-14 days: Involution begins whereby lymphocytes appear in increasing numbers in the medulla. >14 days: Advanced involution whereby there is overall relative depletion of lymphocytes and they mainly occupy the medulla.

Answer 68

Other names: chronic myeloid leukemia, chronic granulocytic leukemia. Incidence: 12.8 cases per 100,000 population per year, 15% of all adult leukemias. M:F=1.8:1. Age distribution: median age at diagnosis 46-53 yrs, occasionally seen in children.

Answer 69

IN BLOOD: Leukocytosis composed of granulocytes of all stages of maturation. Myelocyte bulge, blasts usually less than 1% to 2%. Absolute basophilia in all cases, absolute eosinophilia in 80% of cases. Absolute monocytosis common, but monocytes less than 3% of leukocytes. Thrombocytosis common, can be prominent; thrombocytopenia very rare. IN MARROW: Hypercellular due to granulocytic and megakaryocytic proliferation. Myeloid : erythroid = 10 : 1 to 20 : 1. Widened paratrabecular cuff of immature granulocytes. Basophilia, blasts less than 10%. Small hypolobated (dwarf) megakaryocytes (not micro-megakaryocytes). Mild reticulin fibrosis. Pseudo–Gaucher histiocytes (in approximately 20% to 40% of cases).

Answer 70

FOR BLOOD: LAP (NAP) score low. B12 increased. FOR MARROW: Cytogenetic analysis: t(9;22) or variant (more than 95% of cases). Molecular: BCR-ABL1+ by FISH or PCR (100% of cases). Most cases: major BCR-ABL1, (e13 or14/a2 or 3), p210 protein. Rare cases: minor BCR-ABL1, (e1/a2 or 3), p190 protein. Rare cases: mu BCR-ABL1, (e19/a2 or 3), p230 protein.

Answer 71

Differential diagnosis for chronic phase: Leukemoid reaction. CMML. Atypical CML (Ph-neg, BCR-ABL1-neg). CNL. Other MPNs. Differential diagnosis for accelerated, blast phase: Ph+ ALL. MDS/MPN. AML.

Answer 72

AKA lymphoepithelial sialadenitis AKA myoepithelial sialadenitis. A reactive, focal to diffuse lymphoid infiltrate of salivary glands leading to parenchymal atrophy and degeneration of glandular elements into irregular epithelial complexes. Strong association with Sjogren syndrome; the majority of patients with SS also have BLEL of parotid glands, and are typically bilateral. BLEL occasionally seen independent of SS are usually unilateral and may be secondary to obstruction. Mean age 5th to 6th decade. M:F = 1:3. Potential evolution to extranodal marginal zone B-cell lymphoma.

Answer 73

Well circumscribed but variably encapsulated. Broad range of appearances due to multiple architectural patterns (solid, myxoid, reticular, nested, cord-like). Typically composed of spindled or plasmacytoid cells; may have dominant cell type or mixed morphology; plasmacytoid cells with hyperchromatic, round to oval nuclei and abundant, eccentric eosinophilic cytoplasm (characteristic but not pathognomonic, as also seen in pleomorphic adenoma of palate). Although not common, clear, polygonal (epithelioid), or stellate cells may be seen. Background with variable collagenization; may contain abundant acellular mucoid stroma. Lacks chondroid or myxochondroid matrix. Lacks infiltration, perineural invasion, profound pleomorphism, necrosis, increased mitotic figures. IHC: Reactive with pan-CK, CK7, CK14, p63, GFAP, and S100. Variable reactivity with actin-sm, actin-HHF-35, SMHC, and calponin (actins reactive in spindled cells but typically nonreactive in plasmacytoid cells). Mutations of p53 have been observed. DDx: pleomorphic adenoma, myoepithelial carcinoma, spindled soft tissue neoplasm, plasmacytoma.

Answer 74

A serious but rare (<2% incidence) lesion that occurs in the bones and deep soft tissues of patients with hemophilia, which can be confused with simple bone cyst, aneurysmal bone cyst, osteosarcoma, or angiosarcoma. Recurrent hemorrhages with reparative changes are responsible for the clinicopathologic manifestations. In bone, they may be intraosseous or sub-periosteal and usually develop in the femur, pelvis, and tibia in adults and the small bones of the hands in children. Histologically, areas of extensive hemorrhage, thrombus formation, bone destruction, and florid new bone formation characterize this lesion and, taken out of context, can be misinterpreted as malignant. Juxtacortical and intramuscular lesions exhibit central masses of organizing blood encased by a fibrous capsule that may be composed of 3 distinct layers: an inner hemosiderin-rich collagenous layer, a central layer of dense fibrous tissue, and an outer layer rich in elastin.

Answer 75

Flow cytometry is used to count and sort cells, as well as viral particles, DNA fragments, bacteria, and latex beads. Particles must be in suspension as single cells to be analyzed. If not, they can be made suitable for flow cytometry by the use of mechanical disruption or enzymatic digestion. Size restrictions also apply; cells or particles must be from 1–30 µm in diameter. Specialized flow cytometers are designed to handle smaller particles such as DNA fragments or bacteria.

Answer 76

FACS, an acronym for fluorescence-activated cell sorter, describes the ability of a flow cytometer to physically sort cells in a liquid suspension. To do so, the instrument design has to be modified to electrically charge cells of interest. This is done by first vibrating the sheath stream to break it into drops. The stream of drops flows past two charge (high-voltage) plates where cells of interest are electrically charged with a voltage pulse. Then the flow stream enters an electrical field where charged cells are deflected into suitable collection containers. Unwanted cells are not charged and are not deflected upon passing through the field.

Answer 77

Another less common condition but nonetheless an important cause of hypoproliferative normocytic anemia is MDS. This syndrome, which often presents as a normocytic anemia (although it can on occasion present as mildly macrocytic or as microcytic anemia), is refractory to treatment (e.g., transfusions of packed RBCs). It may present simply as a refractory anemia in its early stages and is thought to progress then to refractory anemia with ringed sideroblasts, and eventually to so-called preleukemic stages, in particular, refractory anemia with an excess of blasts (generally in the myeloid or lymphoid lines) and an excess of blasts in transformation. The condition may also present initially as a refractory cytopenia that involves all three (erythroid, granulocytic, megakaryocytic) hematopoietic cell lines. MDS appears to be a clonal stem cell disorder that is characterized by ineffective hematopoiesis.

Answer 78

Consistently low anion gaps, typically in the range of 1–3 mEq/L, signify the presence of high levels of basic protein, often a monoclonal paraprotein as occurs in plasma cell dyscrasias. Basic protein contains ammonium ions, the counter-ions for which are chloride. Now the “invisible” ion is ammonium, and a measurable increase in chloride ion occurs. This tends to decrease the anion gap. Persistently low anion gaps are a serious sign of possible malignancy (e.g., multiple myeloma).

Answer 79

Similar to HCL, splenic marginal zone B-cell lymphoma has cytoplasmic projections when it involves peripheral blood. But in contrast to HCL with its circumferential fine projections, splenic marginal zone lymphoma is described to have ‘bi-polar’ cytoplasmic projections.

Answer 80

ALK-positive DLBCL has a cytoplasmic granular staining pattern, while the majority of anaplastic large cell lymphomas have nuclear and cytoplasmic staining.

Answer 81

Primary effusion lymphoma is a large cell non-Hodgkin lymphoma localized predominantly in body cavities and occasionally in extracavitary regions. It presents with characteristic lymphomatous effusions in the absence of solid tumor masses, and pleural, peritoneal, and pericardial spaces are most often involved. It is typically associated with HHV-8 infection in immunocompromised individuals, in the setting of HIV infection, organ transplantation, or in rare cases advanced age. Histologically, PEL is characterized by atypical lymphoid cells of B-cell lineage with large nuclei and prominent nucleoli. Demonstration of HHV-8 latent antigens is required for diagnosis, and treatment modalities are limited at this time.

Answer 82

The majority of cases occur in young to middle-aged males, either homosexual or bisexual, with HIV infection and severely immunocompromised. However, it can also occur in HIV-negative individuals who are immunocompromised as a result of solid-organ transplantation or cirrhosis. In rare instances, PEL can affect elderly individuals who are otherwise immunocompetent but live in geographic areas with high HHV8 prevalence, such as the Mediterranean region; these cases may be EBV negative.

Answer 83

Primary effusion lymphoma is clinically unique in that it arises predominantly as a lymphomatous effusion within body cavities such as the pleural, pericardial, and peritoneal spaces, typically without any associated extracavitary masses. A subset of cases develop solid tumors in structures adjacent to the body cavity (eg, the pleura). Cases involving solid masses exhibiting morphology, immunophenotype, and gene expression profiles similar to classical PEL have also been described and subsequently labeled “extracavitary PEL.” Such extracavitary presentations more commonly involve the gastrointestinal tract. The most frequent causes of death in PEL patients, aside from progression of the lymphoma, are opportunistic infections and other HIV-related complications.

Answer 84

Epstein-Barr virus infection can be demonstrated by in situ hybridization for EBV-encoded small RNA (EBER); immunohistochemical studies for EBV latent membrane protein 1 are negative. Molecular studies demonstrate clonal immunoglobulin gene rearrangements and somatic hypermutation, indicating that the cell of origin is a postgerminal center B cell. PCR can demonstrate presence of the viral genome. Cytogenetic studies have not demonstrated any recurrent chromosomal abnormalities.

Answer 85

Primary effusion lymphoma cells typically display a “null” lymphocyte phenotype: CD45 is expressed, but common pan–B-cell (CD19, CD20, CD79a, surface immunoglobulins) and T-cell (CD3, CD4, CD8) markers are absent. Instead, however, markers of lymphocyte activation (CD30, CD38, CD71, EMA, HLA–DR) and plasma cell differentiation (CD138) are often present. Bcl-6 is usually absent. Definitive diagnosis hinges on detection of viral infection by HHV8 in the neoplastic cells. IHC to detect expression of latency-associated nuclear antigen, LANA-1, are currently the standard assay to demonstrate evidence of infection; typically, positive results are characterized by a nuclear dotlike pattern. Epstein-Barr virus infection can be demonstrated by ISH for EBV-encoded small RNA (EBER); IHC studies for EBV latent membrane protein 1 are negative. Viral interleukin 6 is expressed by a variable subset of lymphoma cells, and IHC studies for this protein may be helpful for confirmation.

Answer 86

PEL has to be differentiated from other types of non-Hodgkin lymphoma by its morphologic features and unique immunophenotype. (HIV–positive individuals, for example, may have a Burkitt lymphoma with plasmacytoid differentiation, which can in rare cases present as a lymphomatous effusion.) Pyothorax-associated lymphoma. Plasmablastic lymphoma. Anaplastic large cell lymphoma. Plasma cell myeloma. Although each of these differential diagnoses shares morphologic features with PEL, each can also be distinguished from PEL by the absence of demonstrable HHV8 antigen within neoplastic cells.

Answer 87

Extra antibodies. Transfusion (plasma components not type-specific to patient; IV Ig/albumin). Transplantation. Subgroup of a major blood type (especially subgroup of A (i.e. A2). Rouleaux (multiple myeloma; chronic inflammatory disorders).

Answer 88

Poorly differentiated carcinoma. Melanoma/clear cell sarcoma. Glomus tumor. Gangliocytic paraganglioma. GI endocrine carcinoma. Extramedullary myeloid tumor. GI mucosal benign epithelioid nerve sheath tumor.

Answer 89

HDFN is the destruction of fetal or newborn RBCs by maternal alloantibodies specific for inherited paternal RBC antigen(s). The maternal IgG is transported across the placenta into the fetal circulation where it binds to the corresponding RBC antigen, targeting the antibody-coated RBCs for destruction by macrophages in the fetal spleen. The fetal marrow initially responds by increasing erythropoiesis and releases many of the newly produced RBCs into the circulation prematurely as nucleated precursors, leading to the term "erythroblastosis fetalis." With worsening anemia, erythropoiesis expands to the liver and spleen, causing organ enlargement and portal hypertension. A resulting decrease in liver production of albumin leads to reduced plasma colloid osmotic pressure, generalized edema, ascites, and effusions known as "hydrops fetalis."

Answer 90

HTLV-1 predominantly infects CD4+ lymphocytes while HTLV-2 preferentially infects CD8+ lymphocytes (and, to a lesser extent, infects CD4+ lymphocytes, B lymphocytes and macrophages).

Answer 91

The immature nucleated red cell also has class I antigens on its surface, but as the RBC matures the expression of class I antigens is diminished. Remnants of class I HLA antigens on red blood cells are also known as Bennet-Goodspeed (Bg) antigens. The antigens are listed with their corresponding class I HLA designation: Bga – HLA-B7, Bgb – HLA-B17, Bgc – HLA –A28.

Answer 92

HLA class II antigens are selectively expressed by dendritic cells, macrophages, B-lymphocytes, and activated T-cells that function in antigen processing and self versus non-self recognition.

Answer 93

The iadult phenotype is a rare, autosomal recessive phenotype found in <1/10,000 donors. In Asia, the iadult phenotype can be associated with congenital cataracts. i antigen is also observed on cord RBCs and reticulocytes and in megaloblastic anemia, leukemia, and chronic hemolytic states as a sign of stressed erythropoiesis. Elevated i antigen is also observed in HEMPAS (hereditary erythroblastic multinuclearity with positive acidified-serum test), a congenital dyserythropoietic anemia.

Answer 94

Anti-I and anti-i are antibodies of IgM isotype, reactive at room temperature. Autoantibodies to I are relatively common and are usually low-titered cold agglutinins. Some anti-I can have IH specificity, reacting stronger with group O and A2 RBC. Although generally benign, hemolysis secondary to high-titered anti-I is observed in cold autoimmune hemolytic anemia (CAIHA). CAIHA can occur in the setting of malignancy and occasionally infection (e.g., Mycoplasma pneumoniae). These antibodies display high thermal amplitude, often agglutinating RBCs at temperatures of 30°–34° C. In contrast, alloanti-I is relatively rare and is found as a naturally occurring antibody in iadult individuals.

Answer 95

Patients with multiple myeloma, Waldenström's macroglobulinemia, and hyperviscosity syndromes have high concentrations of abnormal serum proteins that change the net surface charge on the RBC membrane. The cells thus cluster together in clumps that resemble macroscopic hemagglutination. Plasma expanders, such as dextran and hydroxyethyl starch, as well as some intravenous X-ray contrast materials can also cause rouleaux formation.

Answer 96

Rouleaux can be differentiated from true agglutination by direct microscopy (1) by the classical “stacked-coin” formation in rouleaux, and (2) by the loss of rouleaux after washing and resuspension in saline.

Answer 97

In vivo hemolysis is the result of binding of antibody to a patient's RBCs in the peripheral vessels of the extremities, which are cooler (32° C and lower). As the cells recirculate to the body core and warm to 37° C, complement is activated and cells are destroyed. Hemolysis of cells may occur intravascularly but occurs more commonly via extravascular (C3b) pathways by macrophages in the reticuloendothelial system. Hemolysis may be chronic or episodic, depending on the thermal range of the antibody, and may be triggered by exposure to cold temperatures.

Answer 98

Myeloblast --> promyelocyte --> myelocyte --> metamyelocyte --> bands --> polymorphonuclear neutrophils.

Answer 99

The term "large granular lymphocytes (LGLs)" usually refers to NK cells, because up to 75% of LGLs function as NK cells.

Answer 100

Leukoerythroblastosis indicates severe disruption of the marrow by overwhelming infection, myelofibrosis, or bone marrow invasion by cancer, and may be associated with extramedullary hematopoiesis. A leukoerythroblastic reaction in infants can occur with severe hemolytic anemia (eg, erythroblastosis fetalis) or the rare bone disorder, osteopetrosis, in which failure of osteoclasts to resorb bone causes loss of hematopoietic marrow space and resultant extramedullary hematopoiesis.

Answer 101

Hyperleukocytosis refers to a WBC count greater than 100,000/mL, and is seen almost exclusively in leukemias and myeloproliferative disorders.

Answer 102

Leukostasis, or sludging of WBC in small vessels of the brain, lungs, and kidneys, is an oncologic emergency that may cause life-threatening cerebral infarcts, cerebral hemorrhage, or pulmonary insufficiency caused by impaired blood flow. It is most common with acute myelogenous leukemia.

Answer 103

Leukostasis is more common in acute myelogenous leukemia than in acute lymphoblastic leukemia, because myeloblasts are larger and more adhesive than lymphoblasts; it is rarely seen in chronic leukemias, even with extremely high WBC counts.

Answer 104

Because the normal spleen retains a large number of leukocytes, asplenia is associated with an increased WBC count. Splenomegaly may cause relative lymphocytosis as a result of splenic sequestration of granulocytes.

Answer 105

Corticosteroids, which demarginate granulocytes, decrease neutrophil release from the marrow, and reduce neutrophil egress from the circulation, frequently cause leukocytosis.

Answer 106

Transient myeloproliferative disorder (TMD) is seen in up to 10% of patients with Down syndrome (trisomy 21). TMD may also be seen in patients with trisomy 21 mosaicism who are phenotypically normal. TMD is characterized by peripheral blood leukocytosis in early infancy, and may include circulating myeloblasts in association with an accumulation of megakaryoblasts in the blood, liver, and marrow. TMD typically persists for several weeks and resolves spontaneously in most patients, but up to 30% of affected patients later develop acute megakaryoblastic leukemia.

Answer 107

The diagnosis of SM requires the presence of either 1 major criterion and 1 minor criterion, or 3 minor criteria. Major criterion: Multifocal compact infiltrates of mast cells (>15) in extracutaneous organs. Minor criteria: 1. Presence of >25% atypical or spindle-shaped mast cells in extracutaneous organs. 2. Detection of KIT mutation D816V in extracutaneous organ(s). 3. Expression of CD2 or/and CD25 in extracutaneous mast cells (this is aberrant expression). 4. Serum tryptase concentration >20 ng/mL (with the exception of cases with associated clonal myeloid neoplsm).

Answer 108

Bone marrow. Other extracutaneous organs involved include liver, spleen, lymph nodes, and GI tract.

Answer 109

Also called BSAP, a B cell-lineage specific activator protein at 9q13. Member of paired box (PAX) family of transcription factors, which have a novel, highly conserved DNA-binding motif, known as the paired box; encodes BSAP expressed at early stages of B-cell differentiation, also in developing CNS and testis. Detected in B cells from pro-B cell stage to plasma cell stage where it is downregulated. Required for progression of B cell development beyond the early pro-B cell stage. Uses: Detection of pre-B cells (PAX5+, more sensitive and specific than CD20). Diagnosis of Reed-Sternberg cells in classic Hodgkin lymphoma (PAX5+) versus T / null cell anaplastic large cell lymphoma (PAX5-), although rarely positive in T cell lymphomas. Diagnosis of lymphoplasmacytic lymphoma / plasmacytoid differentiation in marginal zone lymphoma (PAX5+) versus plasmacytoma (PAX5-).

Answer 110

Nonneoplastic MCs have round to ovoid nuclei, abundant metachromatic or basophilic granules, and are generally individually dispersed in tisuse. Neoplastic MCs have atypical features such as elongated and spindled morphology and reduced or absent granularity. In addition, they often occur in clusters in tissue, and this in combination with their spindled morphology may lead to their misinterpretation as fibroblasts.

Answer 111

Activating somatic point mutations of the KIT gene are associated with mastocytosis and are encountered in most (>80%) of sporadic cases.

Answer 112

Sclerosing Angiomatoid Nodular Transformation (SANT) of the spleen is a rare benign lesion of the spleen with unknown etiology. SANT is classically considered to be a female-predominant disease. Most lesions are found incidentally on imaging. Although SANT has specific imaging findings, the DDx from other splenic tumors or malignant lesions is very difficult. Histopathologically, these tumors reveal multiple confluent angiomatoid nodules; these nodules are surrounded by concentric collagen fibers exhibiting an inflammatory and myofibroblastic response and are accompanied by numerous erythrocytes and siderophages. The nodules are populated by endothelial cells, phenotypically recapitulating normal splenic vasculature, such as sinusoids, capillaries, and small veins. Nuclear atypia is minimal, mitotic figures are extremely rare, and necrosis is consistently absent. This lesion has a unique immunohistochemical profile characterized by CD34−CD31+CD8+ sinusoids, CD34+CD31+CD8− capillaries, and CD34−CD31+CD8− small veins. CD68 is positive in macrophages. Splenectomy is an effective technique for the management of SANT. Prognosis is good, with no recurrence after splenectomy.

Answer 113

Vascular neoplasms are the most common primary nonhematopoietic tumors of the spleen. They include hemangiomas, littoral cell angiomas, splenic hamartomas (SHs), lymphangiomas, hemangioendotheliomas, angiosarcomas, and Sclerosing Angiomatoid Nodular Transformation (SANT).

Answer 114

Skin, bones, GI tract.

Answer 115

Reticulated platelets (retPLTs) are platelets that are newly released from bone marrow megakaryocytes and still contain RNA. They have a short lifespan in the circulation and therefore reflect current megakaryopoietic activity, exactly comparable with reticulocytes and erythropoiesis. Reticulated platelets have clinical utility because they can help distinguish bone marrow failure from peripheral destruction in thrombocytopenia. Furthermore, retPLTs are an early predictor of bone marrow recovery after chemotherapy and transplantation.

Answer 116

It produces a BCR-ABL1 fusion with an abnormal tyrosine kinase activity that promotes the characteristic proliferation of progenitor cells in CML and ALL. BCR-ABL1 kinase signaling constitutively activates downstream proteins that promote growth factor-independent proliferation, altered adhesion, resistance to DNA repair, and inhibition of apoptosis that culminates in the malignant transformation of hematopoietic stem cells. The BCR-ABL1 fusion transcript and its resulting kinase have become a key target and biomarker in the treatment and monitoring of CML.

Answer 117

Positive normal: Hematogones (B and T cell precursors) - coarsely granular or speckled pattern of TdT immunofluorescence, which often intensely aligns the nuclear membrane. Cortical thymocytes. Positive disease: B or T cell acute lymphoblastic leukemia/lymphoma - 95%, diffuse and strong, finely granular pattern of TdT immunofluorescence uniformly distributed in the nucleus. Indolent T cell proliferations. Thymoma (lymphocyte predominant). Acute myelogenous leukemia / myeloid sarcoma - variable, often weak and focal. Blastic plasmacytoid dendritic cell neoplasm - 60%. Merkel cell carcinoma - >50%. Negative: Myeloid cells; mature leukemias/lymphomas including Burkitt, diffuse large B cell, MALT, mantle cell, prolymphocytic leukemia (T cell), small cell lung carcinoma (usually); sarcomas.

Answer 118

Clinically, patients with exon 12 mutations typically present with isolated erythrocytosis and suppressed erythropoietin, in contrast to the trilineage hyperplasia characteristic of patients with V617F mutation. Bone marrow from patients with exon 12 mutation often exhibits nonspecific morphology, with isolated erythroid proliferation and absence of prominent megakaryocyte atypia and clustering. Demonstration of exon 12 mutation in these patients is particularly helpful for ruling out reactive erythrocytosis.

Answer 119

JAK2 V617F (~96%) or JAK2 exon 12 mutations (~3%).

Answer 120

False. Other hematological neoplasms (eg, myelodysplastic syndrome, chronic myelomonocytic leukemia, acute myeloid leukemia, and acute lymphoblastic leukemia) may harbor JAK2 and MPL mutations in low frequencies. Because JAK2 and MPL mutations are not completely specific for MPN, finding of these mutations in isolation does not warrant a diagnosis of MPN.

Answer 121

The JAK2 gene maps to chromosome band 9p24 and encodes a tyrosine kinase protein composed of 1132 amino acids. It contains three critical domains: JH1, JH2, and four-point-one, ezrin, radixin, moesin (FERM) homolog domains. JAK2 protein kinase activity is activated by phosphorylation of its kinase domain. Activation of JAK2 induces signal transduction from both type 1 and type 2 cytokine receptors. Constitutive activation of JAK2 by either point mutation or fusion protein causes activation of the JAK/STAT pathway. The activated JAK2 causes phosphorylation of STATs, which then dimerize and translocate to the nucleus, where they regulate gene transcription. The constitutive tyrosine phosphorylation activity promotes cytokine hypersensitivity.

Answer 122

The MPL gene maps to chromosome band 1p34 and encodes the thrombopoietin receptor, which binds to thrombopoietin, the primary cytokine that regulates megakaryocyte development and platelet production, as well as hematopoietic stem cell homeostasis. Binding to thrombopoietin to MPL leads to activation of JAK2, which phosphorylates MPL and initiates a cascade of downstream signaling events that regulate cell survival, proliferation, and differentiation. The mutation W515L results in impaired function of the autoinhibitory region and subsequent ligand-independent thrombopoietin receptor activation. This then leads to subsequent activation of downstream tyrosine kinases and activation of transcription factors STAT3 and STAT5, which in turn leads to transformation of hematopoietic cells into cytokine-independent clones, resulting in megakaryocytic hyperplasia and marrow fibrosis. The mutation Y252H, which is located in the extracellular domain of MPL, confers hypersensitivity to thrombopoietin and increases the generation of megakaryocyte colonies in vitro and leads to increased thrombopoietin signaling and cell growth and survival.

Answer 123

The differential diagnosis of small round cell tumors of the kidney includes blastema-predominant Wilms tumors, lymphoblastic lymphoma, clear cell sarcoma, small cell carcinoma, monophasic synovial sarcoma, neuroblastoma, rhabdomyosarcoma, desmoplastic round cell tumor, rhabdoid tumor and extraskeletal Ewing sarcoma/PNET.

Answer 124

In unconjugated hyperbilirubinemia... If the step affected is heme conversion to unconjugated bilirubin (increased production), the pathologic process is extravascular hemolysis. If the step affected is delivery of unconjugated bilirubin to liver, the potential pathologic processes are blood shunting (cirrhosis) or right heart failure. If the step affected is uptake of unconjugated bilirubin into hepatocyte, the potential pathologic processes are Gilbert syndrome and drugs such as rifampin. If the step affected is conjugation of bilirubin in hepatocyte, the potential pathologic processes are Crigler-Najjar syndrome and hypothyroidism.

Answer 125

Physiologic jaundice. Breast milk jaundice. Polycythemia. Hemolysis (HDN, hemoglobinopathies, inherited membrane or enzyme defects). Bowel obstruction (Hirschprung disease, cystic fibrosis, ileal atresia). Inherited disorders of bilirubin metabolism (Gilbert syndrome, Crigler-Najjar syndrome).

Answer 126

A benign acquired condition (associated with celiac disease, lymphoma, HIV infection, monoclonal gammopathy, rheumatoid arthritis, and ulcerative colitis) with an incidence of ~1%, in which apparently healthy individuals have markedly elevated serum amylase levels (with low urine amylase levels), due to Ig-amylase complexes.

Answer 127

Electromotive and endosmotic. When a charge is applied (from a power source), this creates an electromotive force. The solid support has a slight negative charge and is drawn toward the positive pole (anode), but, being a solid support, it cannot move. There is instead a compensatory flow of the fluid buffer towards the negative pole (cathode). This buffer flow is called endosmosis and has the capacity to carry with it substances suspended within the medium. Since most proteins bear a net negative charge, electromotive force tends to pull them to the anode (positive pole), whereas endosmosis pulls them toward the cathode (negative pole). In most proteins, the electromotive force exceeds the endosmotic force, and they move to variable extents towards the anode. However, gamma globulins have a weak net negative charge and the endosmotic force displaces them toward the cathode.

Answer 128

MCV is the volume (in fL = 10^-9 uL = 10^-15 L) of the average circulating red blood cell. MCH is the hemoglobin content (in pg/red cell) of the average circulating red blood cell. MCHC is the hemoglobin concentration (in g/dL) within circulating red blood cells (grams of hemoglobin per 100 mL of packed red blood cells).

Answer 129

Toxoplasma.

Answer 130

Bacillary angiomatosis, Kaposi sarcoma, palisaded myofibroblastoma, inflammatory pseudotumor of lymph node.

Answer 131

Yes. The majority of cases that transform to acute leukemia are of the myeloid lineage.

Answer 132

PTGC is an uncommon condition, often presenting as unexplained, asymptomatic, persistent or recurrent lymphadenopathy. It is more common in men, presenting most often in the head and neck area. PTGC is characterized by the presence in a lymph node of one or more nodules three to five times the size of a typical reactive follicle, with a predominance of small mantle zone B cells, as well as disruption and eventual replacement of the germinal center. While PTGC and nodular lymphocyte predominant Hodgkin lymphoma are often associated, and some patients with PTGC may develop lymphoma at a later date, PTGC is not considered to be a premalignant condition. It may be associated with chronic inflammatory or autoimmune conditions.

Answer 133

Nodular lymphocyte predominant HL and Classic HL. Classic HL has 4 subtypes: nodular sclerosis CHL, mixed cellularity CHL, lymphocyte-depleted CHL, lymphocyte-rich CHL.

Answer 134

CHL has Reed-Sternberg cells, Hodgkin cells (mononuclear variant of RS cells), and lacunar cells (seen in nodular sclerosis subtype). NLPHL has L&H (Lymphocytic & Histiocytic) cells AKA popcorn cells, now known as LP cells.

Answer 135

Cytoplasmic retraction that is a formalin fixation artifact. The artifact is not seen in tissue placed in metal-containing fixatives such as B5, where the cells have ample pale-staining cytoplasm.

Answer 136

100% have lymphadenopathy, which tends to be chronic, asymptomatic, and involving peripheral lymph nodes (cervical, axillary, and inguinal). Mediastinal (2-7%) and bone marrow involvement (1-2%) are rare.

Answer 137

No. It is more indolent, with 75% of patients presenting with stage I-II disease (50-60% of CHL patients present with similar stage disease), and have a better prognosis/survival. .

Answer 138

Favorable prognosis.

Answer 139

Howell-Jolly bodies - DNA fragments. Heinz bodies - Denatured, precipitated hemoglobin (visible only with supravital stain). Pappenheimer bodies - Iron-containing inclusions. Basophilic stippling - Ribosomal RNA. Hemoglobin H inclusion - Precipitated beta-hemoglobin chains (visible only with supravital stain).

Answer 140

Cases with trisomy 12 have predominantly unmutated Ig variable gene regions and therefore have a more aggressive course and worse prognosis. Cases with 13q14 abnormalities usually have mutated immunoglobulin and better prognosis.

Answer 141

Prolymphocytes and paraimmunoblasts.

Answer 142

Osteoblasts are characterized by medium to large plasmacytoid cells with small oval nuclei, indistinct nucleoli, abundant cytoplasm and prominent central cytoplasmic hoffs (pale Golgi zones). Plasma cells can mimic osteoblasts with their eccentric nuclei, abundant blue cytoplasm and prominent perinuclear hoffs; however, plasma cell nuclei should show the characteristic chromatin pattern (clock-face nucleus) and have perinuclear rather then central cytoplasmic hoffs.

Answer 143

t(8;14), Ig heavy chain gene, ~80%. t(2;8), kappa light chain gene, ~15%. t(8;22), lambda light chain gene, ~5%.

Answer 144

Three distinct clinical forms of BL are recognized: endemic (African), sporadic (non-endemic), and immunodeficiency-associated. Although they are histologically identical and have similar clinical behavior, there are differences in epidemiology, clinical presentation, and genetic features between the three forms.

Answer 145

Endemic form: peak age 4-7, M:F = 2:1. Sporadic form: peak incidence in children is age 11 and median age in adults is age 30, M:F = 3-4:1.

Answer 146

PTGC is characterized by the presence in a lymph node of one or more nodules three to five times the size of a typical reactive follicle, with a predominance of small mantle zone B cells, as well as disruption and eventual replacement of the germinal center.

Answer 147

CLL is the most common leukemia in Western countries accounting for approximately 30% of all leukemias in the US. Slight male predominance. CLL is considered to be mainly a disease of the elderly, with a median age at diagnosis of 70 years; however, it is not unusual to make this diagnosis in younger individuals from 30 to 39 years of age. In the US, there is a higher incidence among Caucasians as compared with African Americans or Asian Pacific Islanders. The incidence of CLL is extremely low in Asian countries such as China and Japan, where it is estimated to occur at a frequency that is approximately 10 percent of that seen in countries of the Western world.

Answer 148

DLBCL is the most common lymphoma and accounts for approximately 25% of all NHLs in Western countries. Slight male predominance. Incidence varies by ethnicity, with Caucasian Americans having higher rates than Blacks, Asians, and American Indian or Alaska Natives, in order of decreasing incidence. The median age at presentation is 64 years for patients as a whole, but appears to be younger for Blacks than for Caucasian Americans.

Answer 149

CLL is the most common leukemia in Western countries accounting for approximately 30% of all leukemias in the US. DLBCL is the most common lymphoma and accounts for approximately 25% of all NHLs in Western countries.

Answer 150

AKA Gamna Gandy nodules, siderotic nodules, and fibrosiderotic nodules. They are composed of fibrous tissue and elastic fibers with deposition of iron/hemosiderin and calcium salts and completely disrupt the local architecture of the spleen. They likely form due to scarring at sites of small perivascular hemorrhages. They are seen in cases of congestive splenomegaly due to portal hypertension, sickle cell anemia, and hemochromatosis, and can also be seen in atrial myxoma. Grossly, are small yellow-brown, rusty nodules.

Answer 151

S. pneumoniae.

Answer 152

Panhypogammaglobulinemia occurs in ~10% of patients with multiple myeloma. Most of these patients have a Bence Jones protein (monoclonal free kappa or lambda light chains) in the urine, but lack intact immunoglobulins in the serum. Panhypogammaglobulinemia occurs in ~20% of patients with primary amyloidosis, often associated with a nephrotic pattern (mainly albumin with nonselective globulin loss) in the urine.

Answer 153

A Warthin–Finkeldey cell is a type of giant multinucleate cell found in hyperplastic lymph nodes early in the course of measles and also in HIV-infected individuals. as well as in Kimura disease, and more rarely in a number of neoplastic (e.g. lymphoma) and non-neoplastic lymph node disorders.

Answer 154

Up to 10% of DLBCL are positive for CD5. In this case, make sure it is not CLL/SLL or mantle cell lymphoma that has transformed.

Answer 155

EBV belongs to the gamma-herpesvirus subfamily of herpes virus along with HHV-8. The virus gains entry into the body by infection of B-lymphocytes by the interaction between the major viral glycoprotein gp350 and the complement receptor CR2 which is expressed on B-cells. Following primary infection there is the expression of lytic cycle proteins resulting in the release of infectious virus and generalized seeding of B-cells throughout the body.

Answer 156

These include six EBV nuclear antigens (EBNA-1, 2, 3A, 3B, 3C, and LP), three latent membrane proteins (LMP1, 2A, 2B) localized in the plasma membrane of the infected B cells, and two small non-polyadenylated nuclear RNAs, EBER1 and EBER2 (which far often used as sensitive markers for the presence of EBV within a cell). Three patterns of latency (I, II, and III) are identified depending on the expression of these genes.

Answer 157

EBV belongs to the gamma-herpesvirus subfamily of herpes virus along with HHV-8. The virus gains entry into the body by infection of B-lymphocytes by the interaction between the major viral glycoprotein gp350 and the complement receptor CR2 which is expressed on B-cells. Following primary infection there is the expression of lytic cycle proteins resulting in the release of infectious virus and generalized seeding of B-cells throughout the body.

Answer 158

BZLF1, which represents the Z gene of the virus that is implicated in the switch from latency to lytic cycle of the virus causing its replication; all of the other markers including EBER-1 are considered latency genes and do not necessarily reflect replicating virus or active infection.

Answer 159

Endemic Burkitt lymphoma: 95-100%. Sporadic Burkitt lymphoma: 20-30%. Infectious mononucleosis: 100%. Nasopharyngeal carcinoma: 100%. Chronic active EBV infection: 100%. Mixed cellularity Hodgkin lymphoma: 60-80%. Nodular sclerosis Hodgkin lymphoma: 20-40% Fatal IM/X linked lymphoproliferative syndrome: 100%. Primary CNS lymphoma: 100%. Posttransplant lymphoproliferative disorder: 80%. Oral hairy leukoplakia: 100%. Smooth muscle cell derived tumor in immunodeficient individuals: 100%. Nasal T/NK cell lymphomas: 100%. Angioimmunoblastic lymphadenopathy: 30%. Gastric carcinoma (undifferentiated carcinoma of the nasopharyngeal type): 100%. Gastric carcinoma (adenocarcinoma: 5-15%).

Answer 160

~30% of FHLH cases are due to mutations in the gene encoding perforin (PRF1, 10q21-22), and 20-25% of cases are due to mutations in Munc 13-14 (UNC13D, 17q25). Acquired forms of HLH are typically triggered by infections, especially viral infection such as EBV, CMV, other herpes viruses, and parvovirus B19. Other forms of infection which trigger HLH include bacterial, fungal, and protozoan infections, especially Leishmaniasis. It is important to note that genetic forms of HLH may also be triggered by infection, and isolation of a causative agent does not distinguish primary and secondary forms. Malignancies associated with HLH include primary lymphomas, an association that is more common in adults than in children. Specifically, ALCL is a frequent associated malignancy. HLH in the setting of autoimmune disease has been distinguished from other forms and is called "macrophage activation syndrome" or " reactive hemophagocytic syndrome." This is most often reported in association with systemic-onset juvenile idiopathic arthritis, but may also be seen with LE and other collagen vascular diseases.

Answer 161

Osteolytic metastases: breast cancer, multiple myeloma, lymphoma, leukemia. Humoral hypercalcemia (PTHrP): squamous cell carcinoma (lung, head and neck), RCC, breast cancer, bladder carcinoma, ovarian carcinoma, non-Hodgkin lymphoma, CML, leukemia, lymphoma. Tumor production of calcitriol: lymphoma (Hodgkin, non-Hodgkin, lymphomatosis/granulomatosis), ovarian dysgerminoma.

Answer 162

Increased production of 1,25-dihydroxyvitamin D (calcitriol) is the cause of almost all cases of hypercalcemia in Hodgkin lymphoma and approximately one-third of cases in non-Hodgkin lymphoma. An occasional patient with Hodgkin lymphoma, however, has hypercalcemia due to PTHrP (humoral hypercalcemia of malignancy), as do some with non-Hodgkin lymphoma.

Answer 163

A rare mature CD4+ T-cell neoplasm caused by HTLV-1. Endemic areas: southern Japan, Africa, the Caribbean basin, and Latin America. Mean age 60 yo, range 20-80 yo. M:F = 1.5:1. 4 variants: acute (60%), lymphomatous (20%), chronic (15%), smoldering (5%).

Answer 164

Major paths of viral transmission are breast feeding, blood exposure, and unprotected sex. The lifetime risk of progression to ATLL in an HTLV-1-positive patient is 2.1% for women and 6.6% for men.

Answer 165

An autosomal dominant disorder characterized by rheumatoid arthritis, splenomegaly, and neutropenia. It is seen mainly in white males. The low frequency in blacks may be related to the low frequency of HLA-DRw4, which shows association with Felty syndrome. Risk factors including long-standing RA with high RF titers.

Answer 166

MPO stains the primary (azurophilic) granules indicative of granulocytic differentiation. Fine dusty positivity may be seen in monoblasts. It is negative in lymphoblasts, erythroblasts, and megakaryoblasts.

Answer 167

MPO degrades quickly in wet specimens, but is stable in smears for up to 1 month.

Answer 168

Granulocytic and monocytic cells.

Answer 169

The granulocytic series. Monocytes and lymphocytes are negative.

Answer 170

They stain cells of the monocytic series and, to variably lesser extents, megakaryocytic, lymphocytic, granulocytic, and erythroid series.

Answer 171

Nonspecific esterases (include alpha naphthyl acetate esterase and alpha naphthyl butyrate esterase) mainly stain cells of the monocytic series. Monocyte NSE activity is inhibited by sodium fluoride (NaF).

Answer 172

PAS is positive in most lymphoid and some myeloid blasts.

Answer 173

In ALL, it shows "block" positivity, often encircling the nucleus in a "rosary bead" fashion. In AML, when positive, it is usually a diffuse, granular positivity.

Answer 174

Naphthol AS-biphosphate.

Answer 175

Bands and neutrophils are scored on the intensity of cytoplasmic staining from 0 to 4+ until 100 cells are counted. The number resulting from the sum of the 100 values is reported as the LAP score. Normal adults score in the range of 40-120.

Answer 176

Peripheral blood or bone marrow smears are fixed and incubated in an alkaline-dye solution of naphthol AS-MX phosphate and fast blue RR salt or fast violet B salt. As a result of phosphatase activity, naphthol AS-MX is liberated and immediately coupled with a diazonium salt, forming an insoluble, visible pigment at the sites of phosphatase activity.

Answer 177

Normal adults score in the range of 40-120. Low LAP scores are seen in PNH, some MDSs, congenital hypophosphatasia, CML (LAP score is 0-15), and neonatal septicemia (LAP paradoxically decreased). Elevated levels (>180) are seen in leukemoid reactions, non-CML MPDs, glucocorticoid administration and 3rd trimester of pregnancy.

Answer 178

Stokes shift is the difference (in wavelength or frequency units) between positions of the band maxima of the absorption and emission spectra of the same electronic transition. This is used in flow cytometry: the original/absorbed wavelength determines size and complexity of the cell, and the fluorochrome-emitted wavelength determines antigen expression.

Answer 179

Compensation is the process which corrects the detected "spillover" of the emission of one fluorochrome into the detector designed to collect the emission from another fluorochrome. The primary purpose is to allow the measurement of the true fluorescence in the fluorescence channel contaminated by the spillover.

Answer 180

AKA BCL1 (B-cell leukemia/lymphoma 1) AKA PRAD1 (parathyroid adenomatosis 1). On 11q13.3. Encodes the cyclin D1. Mainly nuclear localization. No normal expression in lymphocytes.

Answer 181

It is also found in B-prolymphocytic leukemia, plasma cell leukemia, and splenic lymphoma with villous lymphocytes. It is found rarely in chronic lymphocytic leukemia and multiple myeloma.

Answer 182

BCL2 (B-cell leukemia/lymphoma 2) is located on 18q21.33. In normal and reactive lymph nodes, it is expressed by mantle cells and the small number of mantle cells that normally permeate the follicle center. It is an inhibitor of apoptosis (although there are other members of the bcl-2 family that are pro-apoptotic), so its expression is inhibited in germinal centers, where apoptosis forms part of the B-cell production pathway.

Answer 183

BCL6 (B-cell Lymphoma 6) AKA BCL5, LAZ3, ZBTB27, ZNF51, and BCL6A is located on 3q27.3. The gene product is a critical transcription factor responsible for normal secondary follicle formation during the germinal center reaction in lymphoid tissues and for proper T-cell-dependent Ab responses upon exposure to Ag. Accordingly, BCL6 is strongly expressed by germinal center B cells (GCBs) but is not present in naive or post-GCBs. BCL6 is thought to protect normal GCBs during the affinity maturation process (i.e., somatic hypermutation) in part by downregulating proapoptotic stimuli elicited by physiologic DNA double-strand breakage.

Answer 184

CD2 is a surface antigen that interacts with lymphocyte function-associated antigen (LFA-3) and CD48/BCM1 to mediate adhesion between T-cells and other cell types. It is expressed by T lymphocytes and NK cells, from a very early stage.

Answer 185

Cytoplasmic expression precedes surface expression and may be detectable by IHC (eg, in immature T cells and NK cells) when surface expression is not detected by flow cytometry.

Answer 186

A subset of T lymphocytes, specifically T helper/inducer cells. It is also expressed by monocytic (promonocyte and monocyte) and dendritic cells.

Answer 187

Anywhere from 2-6:1.

Answer 188

CD4+/CD8+ T cells are normally found only in the thymic cortex.

Answer 189

Occasionally, patients have increased polyclonal benign circulating CD19+/CD20+/CD5+ B cells, particularly in rheumatoid arthritis.

Answer 190

It is a T cell cell surface protein that plays an important role in T cell-B cell interaction in early lymphoid development. There is membrane expression early during T cell development, before TCR rearrangement; persists until terminal stages of T cell development. It is expressed by normal and neoplastic T cells and NK cells.

Answer 191

AKA MME (membrane metallo-endopeptidase), CALLA (Common Acute Lymphoblastic Leukemia Antigen), neutral endopeptidase 24.11, neprilysin, and enkephalinase. It is a cell membrane metallopeptidase which inactivates bioactive peptides.

Answer 192

Normal: PreB cells, preT cells, follicular center (germinal center) cells, granulocytes.

Answer 193

AKA ITGAX (integrin, alpha X (complement component 3 receptor 4 subunit)), CR4, MAC-1, SLEB6, and LeuM5. It is an integrin. Clears opsonized particles and immune complexes, and also binds to fibrinogen and is involved in adhesion of monocytes and neutrophils to endothelium and chemotaxis.

Answer 194

Normal: granulocytes, monocytes, NK cells, dendritic cells, 50% of activated CD4/CD8+ T cells. Disease: hairy cell leukemia (classic and variant), 81% of lymphoplasmacytic lymphoma, 50% of AML-M4 and M5.

Answer 195

AKA ANPEP (alanyl (membrane) aminopeptidase), APN, GP150, LAP1, P150, and PEPN. It has varied functions related to enzymatic degradation. It is a myeloid antigen, positive in granulocytic cells and precursors (but CD33 is more specific).

Answer 196

AKA lipopolysaccharide receptor and monocyte differentiation antigen. It is a GPI linked pattern recognition receptor that detects antigenic molecules on the surface of bacteria (lipoteichoic acid on gram positive, LPS on gram negative), myobacteria (glycolipids) and fungi (mannans), as part of the innate (non-adaptive) immune system (adaptive immune system refers to lymphocytes recognizing microorganism proteins via T cell receptors and antibodies).

Answer 197

AKA FUT4 (fucosyltransferase 4 (alpha (1,3) fucosyltransferase, myeloid specific)), Leu-M1, ELFT, LeX (Lewis X), SSEA-1. It is a carbohydrate that mediates phagocytosis and chemotaxis. Uses: Granulocytic marker. In Hodgkin lymphoma, there is membranous, diffuse cytoplasmic, or faint golgi-zone staining of Reed-Sternberg cells; this can be used to confirm diagnosis, or to differentiate Hodgkin lymphoma (CD15+) from ALCL (CD15-).

Answer 198

AKA FCGR3A (Fc fragment of IgG, low affinity IIIa, receptor (CD16a)), FCG3, FCGR3, IGFR3. It is used as an NK cell, granulocyte, and monocyte/macrophage marker.

Answer 199

AKA B4, CVID3. It forms a complex with CD21, CD81 and CD225 in the membrane of mature B cells and regulates B cell development, activation and differentiation. It is expressed by B cells (from the pre-B stage onward) and follicular dendritic cells.

Answer 200

CD19 is expressed by B cell from the pre-B stage onward and is positive in B cell lymphoma and leukemias, but it often weak/negative in FL and DLBCL. It may be present in some cases of AML, especially AML with t(8;21)(q22;q22).

Answer 201

Normal plasma cells are characterized by expression of bright CD38, CD138, CD27, dim CD45, and dim CD19. Typically, aberrant antigen profiles in neoplastic plasma cells include expression of CD28, CD56, CD20, CD117 (less commonly CD13, CD33, CD44, or CD49d), diminished CD27, diminished CD38, and the complete absence of CD19 and/or CD45.

Answer 202

A phosphoprotein expressed on the surface of B-cells (from late pro-B cells through memory cells; it is not expressed on early pro-B cells or plasma cells). It is encoded by the MS4A1 gene (membrane-spanning 4A gene family).

Answer 203

Antibody FMC-7 appears to recognise a conformational variant/epitope of CD20, also known as the FMC-7 antigen. Cells with weak CD20 tend to be FMC-7 negative, while cells with bright CD20 tend to be FMC-7 positive.

Answer 204

AKA B lymphocyte cell adhesion molecule (BL-CAM), Sialic acid binding immunoglobulin-like lectin/Siglec-2. It is considered a pan-B-cell marker. Is present on the surface of mature B cells and to a lesser extent on some immature B cells.

Answer 205

It is a C-type lectin that is the "low affinity" IgE receptor. It acts as a B cell growth and activation factor, promoting differentiation into plasma cells.

Answer 206

CD21, CD23 and CD35 are dendritic cell markers.

Answer 207

AKA IL-2 receptor alpha chain, IL2RA and TAC antigen.

Answer 208

AKA Ki-1, Ber-H2, and TNFRSF8. Is a cell membrane protein of the tumor necrosis factor receptor family and tumor marker. Is found on normal plasma cells and activated T and B cells. In hematologic malignancy, CD30 (along with CD15) expression is the hallmark of Reed-Sternberg cells in classic Hodgkin lymphoma. It is also found on ALCL. Expression of CD30 (usually focal) is a characteristic feature of mediastinal-type DLBCL.

Answer 209

A transmembrane protein that is a member of the SIGLEC (sialic acid-binding immunoglobulin-like lectin) family of lectins. It is not expressed outside the hematopoietic system. Is classically considered a myeloid marker (along with CD13), but can be expressed in some lymphoid cells. Is positive in almost all AML M0, and in ~80% of AML M1-M5.

Answer 210

It is a cell surface glycoprotein and functions as a cell-cell adhesion factor. In hematology, is a marker of hematopoietic progenitor cells/hematogones/blasts.

Answer 211

AKA ADP-ribosyl cyclase 1/cyclic ADP ribose hydrolase. A glycoprotein that is a multifunctional enzyme. Is associated with a poor prognosis in CLL/SLL.

Answer 212

AKA TNF receptor superfamily member 5. Is a costimulatory protein found on antigen presenting cells and is required for their activation. Hematologically, it is expressed by antigen presenting cells (dendritic cells, macrophages, B cells) as well as neoplastic B cells.

Answer 213

AKA platelet glycoprotein IIb, GPIIb, platelet fibrinogen receptor alpha subunit. In hematology, positivity is seen in platelets, megakaryocytes, and hematopoietic progenitor cells (erythroid, myeloid, megakaryocytes). It is also seen in AML M7 and blasts in transient myeloproliferative disorder.

Answer 214

Integrin alpha-IIb (CD41) is a protein that is encoded by the ITGA2B gene. Integrin beta-3 (CD61) is a protein that is encoded by the ITGB3 gene. Alpha-IIb undergoes post-translational cleavage to yield disulfide-linked light and heavy chains that join with beta-3 to form a fibrinogen receptor expressed in platelets that plays a crucial role in coagulation. Mutations that interfere with this role result in thrombasthenia.

Answer 215

AKA leukosialin or sialophorin. Is a transmembrane cell surface protein that is encoded by the SPN (SialoPhoriN) gene. Is a pan-T-cell marker present on normal and neoplastic T-cells, but is also present on normal and neoplastic granulocytes and some B-cells.

Answer 216

CD43 (AKA sialophorin or leukosialin) is defective or deficient in lymphocytes of patients with Wiskott-Aldrich syndrome. Wiskott-Aldrich syndrome is an X-linked recessive immunodeficiency characterized by thrombocytopenia, eczema, and recurrent infections.

Answer 217

AKA leukocyte common antigen (LCA), or "protein tyrosine phosphatase, receptor type, C" (PTPRC). Is an enzyme that is encoded by the PTPRC gene and is found in nearly all normal and neoplastic leukocytes. However, dim to absent CD45 (usually with strong CD34) is the immunophenotypic signature of myeloblasts, and dim to absent CD45 (with strong CD38) is indicative of plasma cells. Also, CD45 is not expressed in Reed-Sternberg cells (except NLPHD).

Answer 218

The CD45 family consists of multiple members that are all products of a single complex gene (PRPRC). Different subsets of hematopoietic cells express different CD45 isoforms due to variable exon splicing, which can change in response to cytokines. The gene contains 34 exons and three exons of the primary transcripts (these three exons generate the RA, RB and RC isoforms) are alternatively spliced to generate up to eight different mature mRNAs and after translation eight different protein products. The isoforms are: CD45RA, CD45RB, CD45RC, CD45RAB, CD45RAC, CD45RBC, CD45RO, CD45R (ABC).

Answer 219

AKA N-CAM (neural cell adhesion molecule). It is a homophilic binding glycoprotein that contributes to cell-cell or cell-matrix adhesion during development. It is the prototypic markers of NK cells, but also stains other hematologic cells.

Answer 220

AKA Leu7, HNK1 (human natural killer-1), beta-1,3-glucuronyltransferase 1, and glucuronosyltransferase P. Is a glycoprotein enzyme encoded by the B3GAT1 gene that has cell adhesion functions. It is expressed by a subset of normal and neoplastic NK cells, among others.

Answer 221

AKA protectin, complement regulatory molecule, MAC-inhibitory protein (MAC-IP), or membrane inhibitor of reactive lysis (MIRL). Regulates complement mediated cell lysis by inhibiting formation of membrane attack complex (MAC); binds to C8 or C9 components, preventing incorporation of multiple copies of C9 required for complete formation of osmolytic core. It is present on nearly all human cells. Decreased cell surface expression, along with decreased CD55 - DAF, is a feature of the affected clone in paroxysmal nocturnal hemoglobinuria.

Answer 222

Genetic defects that reduce both CD55 and CD59 on erythrocytes produce PNH.

Answer 223

Genetic defects that reduce both CD55 and CD59 on erythrocytes produce paroxysmal nocturnal hemoglobinuria.

Answer 224

AKA KP1, macrosialin. Is a glycoprotein which binds to low density lipoprotein. It is used as a marker of histiocytes and histiocytic tumors, but its specificity is poor, because CD68 is specific to lysosomes, not cell lineage.

Answer 225

CD79 is a transmembrane protein that forms a complex with the B-cell receptor and generates a signal following recognition of antigen by the BCR. CD79 is composed of two distinct chains called CD79A and CD79B (formerly known as Ig-alpha and Ig-beta); these form a heterodimer on the surface of a B cell stabilized by disulfide bonding. CD79a and CD79b are both members of the Ig superfamily. Human CD79a is encoded by the mb-1 gene that is located on chromosome 19, and CD79b is encoded by the B29 gene that located on chromosome 17. Both CD79 chains contain an immunoreceptor tyrosine-based activation motif (ITAM) in their intracellular tails that they use to propagate a signal in a B cell.

Answer 226

Can be used in ALL or small B cell lymphoproliferative disorders when CD20 may be negative or after rituximab (anti CD-20) therapy. Can be used in infarcted lymphomas. Can be used to differentiate preB lymphoblastic lymphoma from Ewing’s sarcoma.

Answer 227

Cutaneous extranodal marginal zone lymphoma.

Answer 228

Low risk: Hyperdiploidy >50 and t(12;21)(p12;q22). Standard risk: t(1;19)(q23;p13). High risk: t(4;11)(q21;q23) and t(9;22)(q34;q11).

Answer 229

Favorable Cytogenetics: inv(16)(p13;q22), t(8;21)(q22;q22), t(15;17)(q22;q12). Intermediate Cytogenetics: +8, t(6;9)(p23;q34), t(9;11)(p22;q23) in children, normal cytogenetics. Unfavorable Cytogenetics: -7, -5, del 7q, t(11q23), inv(3q), t(9;22), complex abnormalities, post-chemotherapy or post-radiation therapy.

Answer 230

Favorable Cytogenetics: inv(16)(p13;q22), t(8;21)(q22;q22), t(15;17)(q22;q12). Intermediate Cytogenetics: +8, t(6;9)(p23;q34), t(9;11)(p22;q23) in children, normal cytogenetics. Unfavorable Cytogenetics: -7, -5, del 7q, t(11q23), inv(3q), t(9;22), complex abnormalities, post-chemotherapy or post-radiation therapy.

Answer 231

pDCs are a rare subset of dendritic cells that are morphologically and functionally unique from conventional dendritic cells (cDCs). pDCs are a small population of bone marrow-derived cells that traffic directly from blood via high endothelial venules to organized lymphoid structures in the steady state, mainly to T-cell areas of lymph nodes and spleen, mucosal-associated lymphoid tissues, thymus and liver. In lymph nodes, they are usually in clusters in paracortical areas. They have more abundant and pale cytoplasm than small mature lymphocytes, and ill-defined cellular borders. They express monocyte-macrophage-associated antigens and certain T cell-associated antigens, but no T lineage-specific antigens.

Answer 232

MBCs are a subset of B cells related to marginal zone cells that may be recognized in several reactive and tumoral lymph node conditions, including toxoplasma lymphadenitis, infectious mononucleosis, and Hodgkin’s lymphoma. They are situated in clusters inside and around intermediary sinuses, adjacent to the subcapsular sinus and forming parafollicular rims. They are typically intermixed with a few segmented neutrophils. The cytological features of MBCs are the presence of abundant pale to clear cytoplasm, medium size, and bland-looking round to indented nuclei with inconspicuous nucleoli.

Answer 233

Q fever, caused by Coxiella burnetii. Fibrin ring granulomas are small, non-necrotizing granulomas that are usually found in the liver and bone marrow in patients with Q fever. These granulomas characteristically contain a ring-like structure consisting of fibrinoid material; they may or may not have a centrally located fat vacuole(s). This type of granuloma, although uncommon, may be seen in many other conditions including a variety of infections (CMV, EBV, MAI, hepatitis A, infectious mononucleosis, visceral leishmaniasis, Lyme disease, Boutonneuse fever, toxoplasmosis) Hodgkin disease, non-Hodgkin lymphomas, and drug reactions.

Answer 234

Lymphomatoid granulomatosis is an angiocentric and angiodestructive EBV-driven B-cell lymphoproliferative disease, in which the neoplastic B-cells are admixed with reactive T-cells.

Answer 235

Brain, kidney, liver, and skin.

Answer 236

The 5q- syndrome is a myelodysplastic syndrome characterized by a defect in erythroid differentiation. Patients have severe macrocytic anemia, normal or elevated platelet counts, normal or reduced neutrophil counts, erythroid hypoplasia in the bone marrow, and hypolobated micromegakaryocytes. It is seen mostly in middle-aged to older women. Survival is usually long and cytogenetic evolution is uncommon.

Answer 237

The lymphoma cells show marked intrasinusoidal infiltration in the spleen, liver, and bone marrow; lymph node involvement is uncommon. The lymphoma cells are cytotoxic T-cells, usually of the delta-gamma receptor type, which express TIA-1 but are usually negative for perforin. The typical phenotype is CD2+, CD3+, CD7+, CD4-, CD5-, CD8- (usually). EBV is negative.

Answer 238

It is typically a mature cytotoxic T-cell lymphoma with a phenotype of CD4-, CD8+. Hemophagocytic syndrome is a frequent complication that when present usually precipitates a rapidly downhill clinical course.

Answer 239

This lymphoma is designated “NK/T” (instead of “NK”) because while most cases appear to be genuine NK-cell neoplasms, some cases are derived from CD56- cytotoxic T cells.

Answer 240

Isochromosome 7q.

Answer 241

The acute subtype (which is the most common subtype) has hypercalcemia the most frequently. Hypercalcemia is less common in the lymphomatous subtype and is absent in the chronic, smoldering, and cutaneous subtypes.

Answer 242

CD2/CD3/CD4/CD5 pos, CD7/CD8 neg.

Answer 243

Rearrangements involving TCL1 (at 14q32.1) are common and relatively specific for T-PLL. These may take the form of either inv 14(q11;q32) or t(14;14)(q11;q32). Another abnormality, t(X;14)(q28;q11), involves a homolog of TCL1, MTCP1 (mature T cell proliferation 1 gene) that is on Xq28. Overall, approximately 90 percent of cases demonstrate chromosome abnormalities involving chromosome 14. Also, abnormalities in chromosome 8 are seen in ~75% of cases, including idic(8p11), t(8;8), and trisomy 8q.

Answer 244

Alkylating agent-related acute myeloid leukemia is characterized by initial presentation as a myelodysplastic syndrome and cytogenetic abnormalities similar to those seen in myelodysplastic syndrome. The risk is related to total cumulative dose and survival is short.

Answer 245

Those caused by (1) alkylating agents or radiotherapy or (2) topoisomerase II inhibitor therapy; both cause direct DNA damage, but with different genetic and clinical features.

Answer 246

(1) Alkylating agents: Occurs median 5 years after initiation (range, 2-11 years). Presents as MDS, AML or MDS/MPN (CMML). Abnormalities of chromosomes 5 or 7 or complex cytogenetic abnormalities. (2) Topoisomerase II inhibitor therapy: Abrupt onset

Answer 247

MDS and AML.

Answer 248

Upper respiratory tract (80% of cases). Other less common locations include GI tract, urinary bladder, CNS, breast, parotid gland, thyroid gland, lymph node, testis, and skin.

Answer 249

DLBCL. Classic Hodgkin lymphoma is also common, but not as common as DLBCL.

Answer 250

An intermediate-sized B cell with a round to oval vesicular nucleus and a prominent, often central, nucleolus; usually found in the proliferative centers of chronic lymphocytic leukemia and small lymphocytic lymphoma. Immunoblasts are larger cells with moderate basophilic cytoplasm, large round nuclei and a similar prominent, central nucleolus. Centroblasts are larger cells with multiple basophilic, peripherally-placed nucleoli.

Answer 251

In classic SLL, the predominant population is small lymphocytes with scant cytoplasm, coarsely clumped chromatin and inconspicuous nucleoli. In the paraimmunoblastic variant, the predominant cells are slightly larger, with moderately abundant cytoplasm, more open/vesicular chromatin and a single prominent, central nucleolus. The paraimmunoblasts have the same staining pattern as classic CLL/SLL (i.e. expression of CD19, CD20, CD5 and CD23, negative for CD10 and FMC7). It is considered the tissue counterpart of a prolymphocytic transformation of CLL.

Answer 252

GI tract most common (50% of all cases); within GI tract, stomach is most common (85%).

Answer 253

FL is defined as a mixture of germinal center B cells, centrocytic and centroblastic, and at least partial follicular growth (nodular) pattern. Although the t(14;18) is typically seen in FL, the definition is based on morphology.

Answer 254

Heinz bodies are denatured haemoglobin due to oxidative damage. They are not seen in normal individuals, as they are removed by the spleen. A small number may therefore be seen post-splenectomy and also with the use of antioxidant drugs or sulfonamides, in G6PD deficiency and with unstable hemoglobins.

Answer 255

The BCL1 gene is rearranged in virtually all cases of mantle cell lymphoma and in some plasma cell neoplasms. The BCL2 gene is rearranged in up to 95% of follicular lymphoma. The BCL6 gene is rearranged in up to 30% of diffuse large B cell lymphoma. BCL10 gene rearrangements have been reported in extranodal MALT lymphoma, but are not characteristic of any lymphoma.

Answer 256

t(11;18)(q21;q21). t(14;18)(q32;q21). Trisomy 3. Trisomy 18. t(1;14)(p22;q32). t(1;2)(p22;p12).

Answer 257

AKA p30/32, MIC2, O13, T cell surface glycoprotein E2, single-chain type-1 glycoprotein. It is part of the Xg blood group system. Positive staining in numerous normal cell types as well as tumors.

Answer 258

AKA human mucosal lymphocyte antigen 1, integrin alpha E beta 7, ITGAE. Stains normal and tumor intraepithelial T lymphocytes. Will stain hairy cell leukemia, enteropathy-associated T cell lymphoma, and some splenic marginal zone lymphomas.

Answer 259

AKA (proto-oncogene) c-kit, tyrosine-protein kinase Kit, mast/stem cell growth factor receptor (SCRFR). It is a receptor for kit protein, a 145 kD tyrosine kinase growth factor receptor protein important for development and survival of mast cells, hematopoietic stem cells, melanocytes, germ cells, and interstitial cells of Cajal. The gene is at 4q11-21, adjacent to PDGFRA.

Answer 260

AKA heparan sulfate proteoglycan, syndecan-1. It is a very specific marker of plasma cells within hematolymphoid proliferations, but is positive in a wide range of epithelial and mesenchymal proliferations.

Answer 261

It is a glycoprotein implicated in apoptosis and other cellular functions. Is strongly expressed in follicular dendritic cell tumors, weak/no expression in other dendritic cell tumors. Positive in ALCL in a discrete golgi pattern (80-100% of systemic cases, 40-60% of primary cutaneous cases). Cytoplasmic positivity in DLBCL (12%); carcinomas of breast, colon, pancreas, prostate; megakaryocytes.

Answer 262

AKA CD227; episialin; Mucin 1, cell surface associated (MUC1); polymorphic epithelial mucin (PEM). Is a large cell surface mucin glycoprotein expressed by most glandular and ductal epithelial cells and some hematopoietic cells. Normally acts as barrier to apical surface of epithelial cells, playing a protective and regulatory role. Shed into the bloodstream of adenocarcinoma patients, used in commercial serum tumor marker assays (CA15-3).

Answer 263

Actin bundling/cross-linking protein with important role in cell motility and adhesion. It is expressed by RS cells and dendritic reticulum cells.

Answer 264

HLA-DR is a MHC (major histocompatibility complex) class II cell surface receptor encoded by human leukocyte antigen complex on 6p21.31. Antigen presenting cells (B cells, dendritic cells, macrophages, monocytes), basophils (immature), precursor T cells and CD4+ T cells.

Answer 265

The segments of DNA that will encode the IgH chain are V (variable), D (diversity), J (joining), and C (constant). The segments that will encode the kappa and lambda light chains are V, J, and C.

Answer 266

SBH: sensitivity is 1-5% of all cells in the sample, and specificity is 60-80%. PCR: sensitivity is 0.001% of all cells in the sample, and specificity is >95%.

Answer 267

Classically, though not usually, patients are described as having episodic hemolysis especially at night. Affected individuals more commonly develop a chronic, normocytic, normochromic anemia. Over time, transient thrombo- and leukopenias develop. Eventually, there may be evolution to aplastic anemia and/or AML.

Answer 268

5% of patients with PRCA have a thymoma. 5-15% of patients with a thymoma have PRCA. The PRCA results from an autoimmune-mediated hypoproliferation of erythrocyte precursors in the bone marrow. This paraneoplastic disorder is more common in older women, and is usually seen with tumors that have spindle cell morphology.

Answer 269

Congenital sideroblastic anemia: X-linked sideroblastic anemia. Mitochondrial transporter SLC25A38 defects. Glutaredoxin 5 (GLRX5) deficiency. Erythropoietic protoporphyria. Congenital sideroblastic anemia without identified molecular defects. Sideroblastic anemia as a component of genetic syndromes (X-linked sideroblastic anemia with ataxia. Myopathy, lactic acidosis, and sideroblastic anemia. Sideroblastic anemia, B cell immunodeficiency, periodic fevers, and developmental delay. Pearson marrow-pancreas syndrome. Thiamine-responsive megaloblastic anemia syndrome). Acquired reversible/metabolic sideroblastic anemia: Alcohol. Drugs (Isoniazid. Chloramphenicol. Linezolid.). Copper deficiency/Zinc toxicity (excess zinc ingestion leads to copper deficiency). Hypothermia.

Answer 270

Patients with FA are at high risk for developing malignancy, particularly MDS, AML (predominant type is with monocytic differentiation - M4 or M5), squamous cell carcinoma of the head and neck or vulva, as well as HCC and gastric carcinoma.

Answer 271

EBV enters the body through the pharyngeal mucosa and subsequently infects B lymphocytes via the C3d receptor (CD21). Reacting to the virus, CD8+ T lymphocytes are responsible for the peripheral blood atypical lymphocytosis that is seen. The site of EBV latency is the B lymphocyte. The EBV genome persists in episomal form within a small population of B lymphocytes, where it usually causes no additional effects.

Answer 272

X-linked lymphoproliferative disorder. It is a manifestation of fulminant acute/primary EBV infection that is frequently fatal and appears confined to males of rare kindreds.

Answer 273

The mechanism of death is usually hepatic necrosis, associated with a pronounced T/NK cell infiltrate. In other cases, affected individuals have manifested hemophagocytosis, agammaglobulinemia, and B cell lymphoma. The underlying genetic defect is found in the SH2D1A (also called SAP) gene that is normally expressed in T and NK cells. The SAP protein is a transmembrane signaling protein that becomes involved in the usual course of immune reaction to viral infection. In those harboring this mutation, for as yet unknown reasons, EBV in particular results in uncontrolled activation of T/NK cells.

Answer 274

A leukocytosis consisting of >50% lymphocytes and >10% atypical lymphocytes, fever, pharyngitis, adenopathy, and a positive serologic test. These criteria are quite restrictive, and many patients routinely diagnosed with mono do not qualify.

Answer 275

Infectious mononucleosis. Streptococcal pharyngitis. Pharyngitis due to other viruses (CMV, HIV, etc.). Toxoplasmosis.

Answer 276

Mononucleosis syndrome can be induced by several drugs, particularly anticonvulsants such as phenytoin, carbamazepine, and antibiotics, such as isoniazid or minocycline. Also, patients with lymphadenopathy and splenomegaly may also have lymphoma.

Answer 277

Primary: Infectious mononucleosis. X-linked lymphoproliferative disorder. Hepatitis. Latent: Burkitt lymphoma (100% of endemic BL, 25% of sporadic BL). Hodgkin lymphoma (EBV in 50-70% of cases). Primary effusion lymphoma (EBV in 70% of cases, HHV8 in 100% of cases). Lymphomatoid granulomatosis. Post-transplant lymphoproliferative disorder (EBV in >95%). Oral hairy leukoplakia. Nasopharyngeal carcinoma (nearly 100% EBV positive in Chinese and Inuit populations, 75% EBV positive in US).

Answer 278

In primary effusion lymphoma, HHV8 is positive in 100% of cases, and EBV is positive in 70% of cases.

Answer 279

EBV-encoded RNA; nuclear RNA portions of EBER 1 and 2 genes. Nuclear stain.

Answer 280

EBER is located to the nuclei of RS/H cells, with little to no expression in the background small lymphocytes. LMP1 is expressed in the cytoplasm and surface membrane of RS/H cells but is rarely expressed in latently infected background lymphocytes of Hodgkin lymphoma.

Answer 281

HHV8. It is associated with all clinical variants of Kaposi sarcoma, with primary effusion lymphoma, and the subset of multicentric Castleman disease seen in HIV+ patients. IHC for LANA-1 shows a characteristic speckled nuclear pattern in cells harboring KSHV.

Answer 282

Arsenic inhibits the oxidative production of ATP. Thus, initial toxicity is manifested in dividing tissue such as GI mucosa, with nausea, vomiting, bloody diarrhea, and abdominal pain. The marrow is affected, causing cytopenias (with erythrocyte basophilic stippling similar to that seen in lead toxicity). Chronic toxicity results in peripheral neuropathy, nephropathy, skin hyperpigmentation and hyperkeratosis (particularly palms and soles) and transverse Mees lines in the nails.

Answer 283

POEMS syndrome (Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal protein, Skin changes) is characterized by the presence of a monoclonal plasma cell disorder, peripheral neuropathy, and one or more of the following features: osteosclerotic myeloma, Castleman's disease (angiofollicular lymph node hyperplasia), increased levels of serum VEGF, organomegaly, endocrinopathy, edema, typical skin changes, and papilledema.

Answer 284

POEMS syndrome (Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal protein, Skin changes).

Answer 285

CLL is thought to be 2 diseases based on molecular profile: One that arises from post germinal center cells which is CD38 and Zap70 negative and has a better prognosis, and another that arises from naive B cells which is CD38 and Zap70 positive and has a worse prognosis.

Answer 286

Del(13q) is a good prognosis. Del(11q), del(17p), and tri 12 are poor prognosis.

Answer 287

There are multiple possible breakpoints in 11q13 (MTC, mTC1, mTC2). Detecting the translocation via FISH with a fusion probe is easier.

Answer 288

Hematologic diseases such as essential mixed cryoglobulinemia, lymphoma, and aplastic anemia. Renal disease, particularly membranoproliferative glomerulonephritis. Autoimmune disorders such as thyroiditis and the presence of autoantibodies. Dermatologic conditions such as porphyria cutanea tarda and lichen planus. Diabetes mellitus.

Answer 289

Light chains have 2 domains: 1 variable and 1 constant. Heavy chains have 4 to 5 domains: 1 variable and 3 to 4 constants. The terminal constant region may insert into the membrane of B cells, or, if free in serum, is called the Fc portion.

Answer 290

Genes for light chains are found on chromosome 2 (kappa) and 22 (lambda). Genes for heavy chains are found on chromosome 14 (gamma, alpha, mu, delta, eta).

Answer 291

Lymphoid stem cell: CD34+, TdT+, HLA-DR+. Pro-B cell (pre-pre-B cell): CD34+, TdT+, HLA-DR+, CD19+, CD10+, Ig H chain rearranging. Pre-B cell: CD34-, TdT-, HLA-DR+, CD19+, CD10+, CD20+, cytoplasmic mu heavy chains + Ig L chain rearranging. B cell: All of the above plus surface Ig, CD21+, CD22+. Plasma cell: Loss of B cell markers (CD19-, CD20-) and cytoplasmic (not surface) Ig+.

Answer 292

Lymphoid stem cell: CD34+, TdT+, HLA-DR+. Prothymocytes: CD34+, TdT+, CD7+. Immature/common thymocytes: CD34-, TdT+, CD1+, CD2+, cytoplasmic CD3+ (surface CD3-), CD5+, CD7+, CD4 and CD8+, TCR rearranged. Mature thymocyte: All of the above, except TdT- and CD1-, surface CD3 becoming +, CD4 or CD8+. Mature T cell: All of the above, except surface CD3+.

Answer 293

IgG has 4 subclasses: IgG1, IgG2, IgG3, IgG4. IgA has 2 subclasses: IgA1, IgA2.

Answer 294

T lymphocytes outnumber B lymphocytes in the blood and tissues by a ratio of about 2:1. T lymphocytes are found in the paracortical areas of lymph node and within periarteriolar lymphatic sheaths in the spleen.

Answer 295

Chromosome 7.

Answer 296

T helper cells bear CD4. T suppressor cells and T cytotoxic cells bear CD8.

Answer 297

CD4+ helper cells must be presented antigen in conjunction with class II MHC molecules (they are class II MHC restricted). CD8+ cytotoxic cells must be presented antigen in conjunction with class I MHC molecules (they are class I MHC restricted).

Answer 298

There is an additional degree of variability created by the terminal deoxynucleotidyl transferase (TDT) enzyme which randomly adds nucleotides into the gene.

Answer 299

Mucosal surfaces and skin.

Answer 300

T cell receptors are expressed in noncovalent association with the CD3 molecule, which assists with transmembrane signaling when an antigen binds to the TCR.

Answer 301

CD16 is the receptor for the Fc portion of gamma heavy chains. Through binding of opsonized cells with this receptor, they mediate antigen-dependent cellular cytotoxicity (ADCC); through this mechanism they are instrumental in combating viral infection and tumor cells.

Answer 302

MHC class II antigens, CD68 (KP-1), and lysozyme. Antigens that are internalized by phagocytosis are processed and presented on the cell surface in association with MHC molecules. T cell stimulation and therefore stimulation of the remaining immune system begins with this. APCs also secrete IL-1.

Answer 303

IL-5, secreted by T cells, specifically stimulates the terminal differentiation release of eosinophils. A sub-subset of CD4+ T cells called Th2 cells stimulates both the production of IgE (secrete IL-4) and eosinophilic infiltration (secrete IL-5), particularly in the setting of parasitic infections.

Answer 304

Parasitic infection. Churg-Strauss syndrome. Hyper-IgE (Job) syndrome. IgE myeloma. Hodgkin lymphoma. IgE is not uniformly elevated in allergic states so is not a useful screening test in that setting.

Answer 305

Cryoglobulins may be present in Waldenstrom macroglobulinemia, myeloma, CLL, SLE, CAH, and viral infections.

Answer 306

100% of blastic mantle cell lymphoma, 90% of mantle cell lymphoma, 25-70% of hairy cell leukemia, 40% of plasma cell myeloma. 10% of CLL/SLL, 8% of plasmacytoma, 4% of classical Hodgkin disease, 2% of DLBCL.

Answer 307

Squamous cell carcinoma, seminoma, and thymoma.

Answer 308

Classic Hodgkin lymphoma: LCA neg, CD20 neg, CD15 pos, CD30 pos, EMA neg, bcl-6 neg, vimentin pos. NLP Hodgkin lymphoma: LCA pos, CD20 pos, CD15 neg, CD30 neg, EMA pos, bcl-6 pos, vimentin neg.

Answer 309

Fludarabine (Fludara), which is a synthetic purine antimetabolite used to treat lymphoid malignancies. It has been shown to cause lymphocytopenia with sustained reduction of CD4+ T lymphocytes. Fludarabine treatment has been associated with susceptibility to TA GvHD. Similarly, a related nucleoside analogue chemotherapeutic agent, cladribine (Litak, Movectro), has also been associated with severe lymphocytopenia and TA-GvHD. The immunosuppressive effect of these two drugs has been noted for extended periods long after cessation of treatment. It is therefore recommended that prior treatment with fludarabine and 2-CDA, whether for a malignant or non-malignant disease, should be considered an indication for irradiation of blood components, even if the treatment was in the distant past.

Answer 310

BPDCN usually occur in elderly pts, with a mean age of 60-70 yrs, but they can present at any age. M:F = 3:1. No racial or ethnic predilection. The tumor is characterized by a high frequency of cutaneous lesions at diagnosis, accompanied by extracutaneous involvement of the bone marrow, peripheral blood, and lymph nodes. At diagnosis, mild to moderate cytopenias are common, but overt systemic symptoms are rare. As the disease progresses, patients develop fulminant leukemia, particularly in the terminal stage of the disease, regardless of whether the patient present with or without cutaneous lesions. In 10-20% of pts with BPDCN, coincident myelodysplasia is identified that can subsequently lead to the development of acute myelomonocytic leukemia or AML.

Answer 311

In cutaneous lesions, BPDCN typically infiltrates the dermis but spares the epidermis. As the disease progresses, it frequently extends into the subcutaneous fat. Extracutaneous disease is present in most pts at diagnosis, often involving the regional lymph nodes. As the disease continues to progress, the peripheral blood and bone marrow become involved. There is enhanced expression of CD4, CD56, and CD123. Karyotypic analysis frequently shows complex aberrations similar to those seen in MDS or AML arising from MDS. There is frequent deletion of tumor suppressor genes, including RB1 CDKN1B, CDKN2A, and TP53.

Answer 312

Treatment of advanced cutaneous T cell lymphoma. But the procedure has been shown to have efficacy in the treatment of numerous other disorders, including GVHD, solid organ transplant rejection, scleroderma, lichen planus, atopic dermatitis, SLE, type 1 DM, and others.

Answer 313

LCS is often an extranodal tumor with skin and bone involvement, but it may present with multi-organ involvement including lymph node, lung, liver and spleen. As with Langerhans cell histiocytosis (LCH), it is a clonal proliferation of Langerhans cells, which are 12-15 microns in diameter with abundant, pale eosinophilic cytoplasm, irregular and elongated nuclei with prominent nuclear grooves and folds, fine chromatin and indistinct nucleoli. Langerhans cells are immunoreactive to CD1a, Langerin and S100. However, LCS compared to LCH has more cytological atypia, a higher proliferation rate and a more aggressive clinical course.

Answer 314

Abscesses containing nuclear dust and neutrophils. Bacteria are difficult to see, even with special stains such as Giemsa or Gram. Histiocytes surround the abscesses and are also seen in the walls of bronchi filled with pus. Venous thrombosis is common.

Answer 315

Smears of blood or bone marrow specimens stained with Wright or Giemsa reagents show Erlichia organisms as round or oval violet bodies, about 1 um in diameter, in the cytoplasm of neutrophils, lymphocytes, monocytes, and macrophages. Clusters of organisms (morulae) can be seen. The bone marrow usually shows erythrophagocytosis and a decrease in myeloid cells and megakaryocytes. In tissue sections, the organism is best seen with Brown-Hopps stain.

Answer 316

Myeloid or monocytic blasts are typically weakly positive or negative with PAS. A granular (may be a finely diffuse pattern or a coarse block pattern) PAS pattern with a negative background is characteristic of lymphoblastic leukemia. PAS staining is positive in the erythroid population in erythroblastic leukemias.

Answer 317

The lesional cell of thymomas is the epithelial cell, which stains with various panCK Abs, as well as Abs to high (34BetaE12) and low (Cam5.2) molecular weight Abs. In addition, most thymomas are p63 positive. Lymphocytes with a thymic phenotype (CD3+, CD1a+, TdT+, CD99+) are present in these tumors, even when they metastasize. CD5 and KIT are expressed by the majority of thymic carcinomas, and only occasionally by thymomas. CD20+ lymphocytes may predominate in micronodular thymomas with lymphoid hyperplasia, and CD20 also stains spindle-shaped thymoma cells, which are also CK+.

Answer 318

The microgranular variant.

Answer 319

CML in blast crisis. 70% of the time it will be an AML, and 30% of the time it will be an ALL (generally precursor B ALL). This shows how CML is actually a stem cell disorder rather than just a myeloid cell disorder.

Answer 320

It is not actually CML. Consider aCML (atypical CML) or CMML instead.

Answer 321

These look like CML but don't have the Philadelphia chromosome. JMML, aCML, and CMML.

Answer 322

It differs according to specific type, but overall it is 25%.

Answer 323

NPM1 is on chromosome 5q35. The mutation is in exon 12. The exon 12 mutations are variable but all lead to small insertions that are usually 4 bp in size (rare cases may result in 5 bp or larger insertions). Normal allele size is 239/240 bp, which mutant is 244 bp. The mutation can be detected by direct sequencing, allele specific PCR reactions designed for individual mutations, or by PCR with subsequent capillary electrophoresis to identify abnormal insertions.

Answer 324

CEBPA is on chromosome 19q31.1. Over 100 non-silent mutations are identified. Most are in-frame insertions in the basic/leucine zipper region or truncations of the N-terminus region. Mutations may be identified by PCR amplification followed by sequencing.

Answer 325

17p13 deletion > 11q22.3 deletion > trisomy 12 > 13q14 deletion. Deletions of 17p13 and 11q22.3 predict a higher risk of disease progression and poorer outcomes following therapy. Deletion of 13q14 (as the sole FISH abnormality) is associated with a lower risk of disease progression and better responses to therapy.

Answer 326

NOTCH1 mutation results in a gain-of-function that is associated with more aggressive disease, poorer treatment responses to chemoimmunotherapy (CIT), and a marked increase (~20x) in the risk of transformation to diffuse large B-cell lymphoma. SF3B1 mutations selectively disrupt spliceosome function and are associated with more aggressive disease and poorer treatment responses to CIT.

Answer 327

CLL patients with more than 98% IGHV sequence identity to the germline allele are considered to be negative for somatic hypermutation (“unmutated”). These patients have a shorter time from diagnosis to disease progression requiring treatment and a poorer prognosis. In contrast, patients with evidence of somatic hypermutation of IGHV (≤ 98% sequence identity to the germline allele) are considered to be “mutated” and have a longer time to first treatment and a better prognosis. It has been observed, however, that CLL patients whose malignant cells utilize the IgVH family VH3-21 allele have a poor prognosis irrespective of the somatic mutation status of the IgVH gene.

Answer 328

DLBCL arising in the setting of CLL. This can be caused by clonal evolution of a CLL cell (~80% of cases) or de-novo development of clonally unrelated DLBCL (~20% of cases).

Answer 329

Clonally related DLBCL has a considerably poorer response to treatment and prognosis.

Answer 330

Interphase FISH testing of CLL cells can detect 17p13 deletion that results in loss of one allele of TP53. This deletion is detected in ~5% of patients requiring initial treatment for CLL and is usually monoallelic. In ~80% of patients with 17p13 deletion, the remaining TP53 allele has a mutation predicted to be dysfunctional - these patients have disrupted p53 function and have poor responses to chemoimmunotherapy regimens because DNA damaging agents are ineffective in patients without an intact DNA damage response pathway.

Answer 331

In ~5% of patients with progressive CLL, TP53 is disrupted in the absence of 17p13 deletion. This may occur due to biallelic mutation, a single mutation with uniparental disomy, or by generation of a dominant negative mutant.

Answer 332

NPM1 mutations are the most common genetic lesion(s) in AML. They are present in 30% of all AMLs and in 50-60% of cytogenetically normal AMLs.

Answer 333

NPM1 mutations occur in exon 12 with greater than 95% occurring as a 4 bp insertion at position 960.

Answer 334

NPM1 mutations occur in exon 12 with greater than 95% occurring as a 4 bp insertion at position 960. Type A mutation is a TCTG insertion, type B is a CATG insertion, and type D is a CCTG insertion.

Answer 335

Type A - 80%, type B - 10%, type D - 5%.

Answer 336

FLT3-ITD is seen in ~15-30% of AML, while FLT3-TKD mutation is seen in ~7% of AML.

Answer 337

CEBPA is first expressed with commitment to the myeloid line and is upregulated during granulocyte differentiation. As a transcription factor, it down regulates c-MYC expression and upregulates myeloid-specific genes, allowing differentiation.

Answer 338

N-terminal mutations lead to increased translation of an alternative 30-kDa isoform with dominant negative activity on the full-length 42-kDa protein. C-terminal mutations result in deficient binding and/or homodimerization activity.

Answer 339

Most T-cell large granular lymphocytic leukemias have a surface CD3+/CD4-/CD8+/CD57+ immunophenotype and express the alpha-beta TCR.

Answer 340

TET2 - 50-60%, SRSF2 - 46%, ASXL1 - 40%, RUNX1 - 15%, SETBP1 - 15%.

Answer 341

TET2 - 20-25%, SF3B1 - 14.5% (80% with ring sideroblasts), ASXL1 - 14%, SRSF2 - 12.4%, RUNX1 - 9-20%.

Answer 342

Lymphomatoid papulosis, MGUS, multicentric Castleman disease.

Answer 343

t(11;17)(q23;q21) ZBTB16/RARA seen at 0.8% frequency. It is resistant to ATRA and has a worse prognosis.

Answer 344

Infants: t(4;11) AFF1-MLL. Children: t(12;21) ETV6-RUNX1. Adults: t(9;22) BCR-ABL1.

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