Dermatopathology Flashcards
(114 cards)
1
Q
Oculocutaneous albinism, retained visual acuity, immunodeficiency, early dementia
A
Chediak-Higashi syndrome
- Presence of giant lysosome-related organelles (melanosomes, platelet-dense granules, neutrophil granules)
2
Q
Disorders with complete absence of melanocytes (3)
A
- Vitiligo
- Piebaldism
- Waardenburg syndrome
3
Q
Decreased visual acuity
Lung and GI problems
Absence of dense bodies within platelets
AlbinismHermansky Pudlak syndrome
A
Hermansky Pudlak syndrome
4
Q
Absence of stage III/IV melanosomes
Photophobia WITH decreased visual acuity
NO dementia
Albinism
A
Oculocutaneous albinism
5
Q
Melanocytes with an INCREASED number of normal-sized melanosomes
Silvery-grey hair
Type 1 has neurologic impairment
Type 2 requires HSCT
A
Griscelli syndrome
6
Q
Newborn with clustered vesicles in an arcuate and polycyclic array
What type of EB is this?
A
EB simplex, Dowling-Meara (EBS-DM) subtype
- Split seen within basal keratinocytes
- Clumping of tonofilaments within keratinocytes’ cytoplasm
7
Q
What type of EB shows absence of anchoring fibrils due to collagen VII defect?
A
Dystrophic epidermolysis bullosa (DEB)
8
Q
What type of EB shows perinuclear stellate inclusions?
A
Autosomal dominant EB
9
Q
Reduced number of hemidesmosoms is seen in what type of EB?
A
Junctional EB
10
Q
Ziehl-Neelson stain is used to identify what type of bacteria?
A
Acid-fast bacteria (i.e., mycobacteria)
11
Q
PCT may have identical histopathologic features to what EB? What type of collagen is targeted in that form of EB?
What findings on DIF can help differentiate the two conditions?
What are the various porphyrin abnormalities in PCT? (3)
A
(Non-inflammatory) EB acquisita (autoantibodies against type VII collagen)
- DIF for PCT shows perivascular IgG > IgM and complement in the upper dermis
- DIF for EBA shows linear BMZ deposition
- In PCT, there is elevated urine, stool, and serum uroporphyrin.
12
Q
What type of EB is this?
On electron microscopy, what cytological structures would be absent in the specimen?
What gene mutation is present?
A
Recessive dystrophic EB (RDEB)
Absence of anchoring fibrils
- Compound heterozygous mutation within the COL7A1 gene, leading to a truncated collagen VII protein that in most cases is nonfunctional
13
Q
Absence of anchoring filaments, hemidesmosomes, and sub-basal dense plates is seen in what type of EB?
A
Herlitz subtype of junctional epidermolysis bullosa (JEB)
- Anchoring fibrils are still present in JEB probably accounting for less severe scarring compared with RDEB
14
Q
Multiple sclerotic fibromas (storiform arrangement of thickened collagen bundles with interspersed spindled cells) are associated with what disease?
What cancers are associated? (2)
A
Cowden disease
- Autosomal dominant mutation of PTEN gene
- Oral papillomas, trichilemmomas, acral keratosis, sclerotic fibromas
- Benign and malignant breast and thyroid tumors
- GI polyps, skeletal abnormalities
15
Q
What syndrome is associated with acrochordons, multiple fibrofolliculomas, and trichodiscomas?
What is the genetic mutation?
What cancer is associated? What lung finding may occur?
A
Birt-Hogg-Dube (BHD) syndrome
Mutation in BHD gene
Associated with renal cell carcinoma and pneumothorax
16
Q
Gardner syndrome is caused by what genetic mutation?
What are the three skin findings of this syndrome?
A
APC gene
Epidermoid cysts, osteomas, desmoid tumors
Associated with colorectal adenocarcinoma
17
Q
What CD is “langerin”?
What is this a marker of?
A
CD207
Marker of Birbeck granules
18
Q
What is the best tissue sample for transmission electron microscopy when evaluating for an inherited blistering disease?
A
A clinically induced blister at the time of biopsy.
19
Q
Pretibial myxedema histology
A
Increased mucin within the upper dermis that separates collagen bundles.
The overlying epidermis may demonstrate acanthosis, papillomatosis, and hyperkeratosis.
20
Q
Muir-Torre syndrome is associated with mutations in which mismatch repair genes? (4)
25% of patients will have what type of skin cancer?
>60% of patients will have what internal malignancy?
A
- Caused by mutations in mismatch repair genes including MLH1, MSH2, MSH6, and PMS2
- Twenty-five percent of patients with MTS also have keratoacanthomas
- More than 60% of patients will have associated colorectal adenocarcinoma
21
Q
KRT1 and KRT10 mutations cause what skin disease?
A
Epidermolytic ichthyosis, in which the pathology is not characterized by acantholysis but rather epidermolytic hyperkeratosis
22
Q
What gene mutation and organelle is involved in Darier disease (keratosis follicularis)?
What gene mutation and organelle is involved in Hailey-Hailey disease (familial benign chronic pemphigus)?
A
- Darier disease (keratosis follicularis) → ATP2A2 mutation, encoding the endoplasmic reticulum Ca2+ ATPase
- Hailey-Hailey disease (familial benign chronic pemphigus) → ATP2C1 gene, which encodes the Golgi-associated Ca2+ ATPase
Think of the disease names, mutations, and organelles involved in ALPHABETICAL order. And the organelles involved are just one letter away from the first letter of the name!!
23
Q
You are called by the neurology team to perform a skin biopsy for the workup of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. You perform a 4-mm punch biopsy of the arm.
In what medium do you place the specimen?
A
Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a neurologic disorder caused by mutations in NOTCH3. Patients with CADASIL have migraines, recurrent strokes, and progressive dementia. Transmission electron microscopy (TEM) of a skin biopsy is the gold standard to detect pathologic findings.
Placing the skin specimen in the correct medium, glutaraldehyde for TEM, is critical for accurate diagnosis.
24
Q
What media should be used for preservation of gout crystals or for fat immunostaining?
A
Alcohol
25
What media should be used for immunofluorescence studies? (2)
Michel transport medium or normal saline
26
EBS with pyloric atresia (EBS-PA) is caused by what genetic mutation?
Mutations in PLEC1 leading to a defective plectin 1 protein
The split described is intraepidermal, which is characteristic of epidermolysis bullosa simplex (EBS).
27
Junctional epidermolysis bullosa (JEB) with pyloric atresia is caused by what genetic mutation?
The split is within the lamina lucida.
28
Ectodermal dysplasia skin fragility syndrome can be caused by what genetic defect?
PKP1 gene defects lead to dysfunctional plakophilin 1 and ectodermal dysplasia skin fragility syndrome.
29
In addition to the clinical findings in the Figure, you see granulation tissue around the mouth, the nape of the neck, and fingernails.
Excessive granulation tissue is a characteristic finding of the Herlitz subtype of junctional epidermolysis bullosa (JEB). This feature is not seen in other inherited epidermolysis bullosa disorders. JEB has a cleavage plane in the lamina lucida.
30
A 65-year-old man has a pink papule on the right side of the abdomen that has been slowly enlarging over one year. A shave biopsy is performed, and the histopathologic findings are shown (Figure).
Fibroepithelioma of Pinkus (FeP) is an uncommon follicular neoplasm that clinically presents as a fleshy pink papule or small plaque, typically on the trunk.
Like BCC, the majority of FeP cases demonstrate **diffuse expression of the proto-oncogene Bcl-2** as well as **androgen receptor**.
31
The majority of trichoblastomas demonstrate peripheral expression of _____ and absence of _____ receptor and stromal \_\_\_\_\_expression.
The majority of trichoblastomas demonstrate peripheral expression of **Bcl-2** and absence of **androgen** receptor and stromal **CD34** expression.
32
Lacazia loboi can be identified using what fungal stain?
Gomori methenamine silver
33
A 50-year-old man comes to the office for evaluation of 2- to 5-mm papules on the face and neck. A biopsy of a characteristic lesion is performed (Figure).
Which three of the following options are most likely associated with this disorder?
Histopathologic examination demonstrates a **fibrofolliculoma**, characterized by epithelial strands extending from the undersurface of the epidermis into the underlying dermis with follicular differentiation and a surrounding fibroblast-rich sclerotic stroma.
This may be associated with **Birt-Hogg-Dube (BHD) syndrome**, which is caused by a mutation in the *BHD* gene. **Renal cell carcinoma and spontaneous pneumothoraces** are strongly associated with BHD syndrome.
34
Immunofluorescence antigenic mapping is an effective technique for the diagnosis of epidermolysis bullosa (EB). Immunomapping with antibodies to BPAg1 and collagen IV allows for differentiation between the major types of EB.
In junctional EB, where do BPAg1 and collagen IV localize to - the roof or the floor?
What about in EBS?
What about dystrophic EB?
Type IV collagen is present in the lamina densa of the basement membrane zone, whereas BPAg1 localizes to the hemidesmosomes of basal keratinocytes. The split in junctional EB is in the lamina lucida, which is below the hemidesmosomes and above the lamina densa. Therefore, BPAg1 would localize to the roof, whereas collagen IV would localize to the floor.
In epidermolysis bullosa simplex, both antigens localize to the floor. In dystrophic epidermolysis bullosa, both antigens localize to the roof.
35
An 18-year-old woman has multiple slowly growing papules on her face, including her cheeks and forehead. A biopsy showed a proliferation of basaloid cells forming multiple small nests, lobules, and small folliculocystic structures containing keratin material. No significant cytologic atypia, mitotic activity, or infiltrative features were identified.
What is the most likely diagnosis for this tumor?
The histologic findings describe a benign follicular neoplasm composed of basaloid cells forming small nests, lobules, and folliculocystic structures, findings typical of **trichoepithelioma**.
36
\_\_\_\_\_ is the most common drug-induced cause of pemphigus vulgaris.
Penicillamine
37
What is pseudoepitheliomatous hyperplasia (PEH)?
Epidermal acanthosis, papillomatosis, and hyperkeratosis that can mimic squamous cell carcinoma
38
True or false: a three-week course of systemic steroids will not affect DIF results.
Deposited immunoglobulin (Ig) must undergo several half-lives (21 days for IgG) to clear completely. **As such, a short course of less than 4 weeks of systemic steroids will likely not affect direct immunofluorescence (DIF) test results.**
39
\_\_\_\_ and ____ stains are useful for metastatic small cell carcinomas of the lung, as they are typically positive for both of these markers.
\_\_\_\_\_ and _____ are the best stains for confirming the diagnosis of a metastatic adenocarcinoma of gastrointestinal tract origin, especially lower gastrointestinal tumors, which are usually positive for both of these markers.
**CK7** and **TTF1** stains are useful for metastatic small cell carcinomas of the lung, as they are typically positive for both of these markers.
**CDX2** and **CK20** are the best stains for confirming the diagnosis of a metastatic adenocarcinoma of gastrointestinal tract origin, especially lower gastrointestinal tumors, which are usually positive for both of these markers.
40
Is dermatitis herpetiformis positive or negative on IIF? What about PCT?
Both DH and PCT are IIF-negative.
41
What is the DIF pattern of PCT?
IgG perivascular "donut" like accentuation and increased signal along the basement membrane zone (BMZ)
42
What are the optimal location and timing for immunofluorescence testing of discoid lupus erythematosus?
**Lesional skin more than 4 to 6 weeks old**
Lesional skin is the preferred site to look for immunoreactants in discoid lupus erythematosus (DLE). Deposition of the classic granular band of immunoreactants takes some time and biopsies of lesions less than 4 to 6 weeks old may yield false-negative results.
43
In bullous pemphigoid and EBA on salt-split skin, do the antibodies bind to the epidermal or dermal side of the salt-split skin? Are the autoantibodies to components of the hemidesmosomes or the anchoring fibrils?
* BP → linear deposition of IgG to the epidermal side (Ab against components of hemidesmosomes)
* EBA → dermal side of salt split skin (Ab against anchoring fibrils)
44
What are the most common underlying neoplasms associated with paraneoplastic pemphigus?
The most commonly associated neoplasms are non-Hodgkin lymphoma (40%), chronic lymphocytic leukemia (30%), Castleman disease (10%), malignant and benign thymomas (6%), sarcomas (6%), and Waldenström macroglobulinemia (6%).
45
Figures 1 and 2 show patient skin (left) and normal control skin (right) incubated with mouse anti-human laminin 332 (beta chain).
What is the diagnosis?
In the normal human skin (Figure 1), there is linear deposition of anti-human laminin332 to endogenous laminin332 along the basement membrane. In the patient's skin, there is some background artifact staining of the epidermis and stratum corneum but linear staining at the basement membrane is not seen, indicating an absence of endogenous laminin332 and the diagnosis of **junctional epidermolysis bullosa, Herlitz type**.
In cicatricial pemphigoid, whether the autoantibody is laminin332 or BPAg2, endogenous laminin332 is present and binding of an exogenous incubated anti-laminin332 antibody will be detectable.
46
What is the best stain for confirming the diagnosis of Merkel cell carcinoma?
CK20 is the best stain for confirming the diagnosis, because it is typically positive, and shows the characteristic perinuclear dot-like staining in MCC.
47
True or false: pityriasis rubra pilaris shows acantholysis.
Histologic examination shows alternating vertical and horizontal orthokeratosis and parakeratosis. **Acantholysis is a microscopic feature that may aid in the diagnosis of pityriasis rubra pilaris.**
48
A 32-year-old woman with a personal and family history of renal cancer was referred to the dermatology clinic with skin lesions on the right arm.
Which of the following diagnoses is most likely to be found from skin biopsy of the lesions?
**Hereditary leiomyomatosis and renal cell cancer (HLRCC) syndrome** is a rare genetic disorder that predisposes individuals to multiple cutaneous leiomyomas, renal cell carcinomas, and in women, uterine leiomyomas.
49
There is a well-known association of ______ with café au lait macules, neurofibromatosis 1, and juvenile myelomonocytic leukemia.
There is a well-known association of **JXG** with café au lait macules, neurofibromatosis 1, and juvenile myelomonocytic leukemia.
50
For each of the following, is there a positive or negative IIF response?
1. PCT
2. Vasculitis
3. Chronic ulcerative stomatitis
4. LP
5. PNP
6. Linear IgA bullous dermatosis
7. Dermatitis herpetiformis
8. Inherited forms of EB
1. PCT → negative IIF
2. Vasculitis → negative IIF
3. Chronic ulcerative stomatitis → negative IIF
4. LP → negative IIF
5. PNP → positive IIF
6. Linear IgA bullous dermatosis → positive IIF
7. Dermatitis herpetiformis → negative IIF
8. Inherited forms of EB → negative IIF
51
What is the expected immunophenotype of Merkel cell carcinoma?
**CK20+** (often exhibiting perinuclear dot-like pattern of positivity) and importantly, **TTF-1-negative**.
52
What is the immunophenotype of an angiosarcoma?
**CD34+ CD31+ ERG+**
53
What is the name of the condition where angiosarcoma occurs secondary to chronic lymphedema?
Stewart-Treves syndrome
54
What is the most common first site of metastasis in angiosarcoma?
Regional lymph nodes
Distant metastases to the lungs and liver are also common.
55
What are adverse effects of BRAF-inhibitor therapy, such as vemurafenib for metastatic melanoma?
Various squamous proliferations (most commonly, verruca vulgaris, keratoacanthomas, and squamous cell carcinomas), hand foot skin reaction, and both neutrophilic dermatoses and neutrophil-rich predominantly lobular panniculitides.
NOT bullous pemphigoid though (seen in anti-PD-1 [nivolumab and pembrolizumab] and anti-PD-L1 blockade [atezolizumab])
56
A 55-year-old woman develops an erythematous nodule on the right lower eyelid (Figure).
Which two of the following immunohistochemical studies would be positive in the tumor cells shown?
Both **adipophilin** and **factor XIIIa (clone AC-1A1)** would be positive in this sebaceous carcinoma.
Adipophilin is a cytoplasmic marker
AC-1A1 mouse monoclonal antibody for factor XIIIa has been shown to highlight the nuclei of sebaceous cells
57
Where are the following allergens found?
1. Dialkyl thiourea
2. Balsam of Peru
3. Cocamidopropyl betaine
4. Quaternium-15
5. Methyldibromo glutaronitrile
1. Dialkyl thiourea → rubber accelerator found in neoprene
2. Balsam of Peru → sweet-smelling natural substance derived from Central American tree
3. Cocamidopropyl betaine → sudsing agent derived from coconut
4. Quaternium-15 → formaldehyde-releasing preservative found in many personal products
5. Methyldibromo glutaronitrile → preservative in many personal, household, and industrial products
58
What is the classic immunophenotype of mycosis fungoides with regards to the following?
* CD3
* CD4
* CD8
* TCR-bF1
* TCR-g
CD3+ CD4+ CD8- TCR-bF1+ TCR-g-
59
What is the classic immunophenotype of primary cutaneous gamma-delta TCL with regards to the following?
CD3 CD4 CD8 TCR-bF1 TCR-g
CD3+ CD4- CD8- TCR-bF1- TCR-g+
60
What is the classic immunophenotype of extranodal NK/T cell lymphoma with regards to the following?
cCD3 CD4 CD8 CD56 EBER
cCD3+ CD4- CD8- CD56+ EBER+
The cells of extranodal NK/T cell only express cytoplasmic CD3 (cCD3) but this distribution cannot be distinguished from membranous CD3 expression (as seen in conventional T-cell lymphomas) using conventional immunohistochemical studies.
61
What is the classic immunophenotype of systemic ALK-positive anaplastic large cell lymphoma with regards to the following?
CD3+ CD30+ ALK+
62
A 68-year-old man has an erythematous patch on his foot as shown (Figure).
What is the best diagnosis?
Kaposi sarcoma
Histologically, these tumors show a spindle cell proliferation with abundant irregular vascular spaces containing lymphocytes. A promontory sign (a small vessel protruding into an abnormal vascular space) can be seen. Plasma cells are often evident. Detection of HHV8 latent nuclear antigen on immunohistochemistry is often a helpful tool.
63
What is the most common mismatch repair gene mutation in Muir-Torre syndrome?
Detection of a deficiency of **MSH2** is most common.
64
Antibodies against what are thought to be the cause of cutaneous lesions in dermatitis herpetiformis (DH)?
What antibodies are considered the most sensitive and specific serologi marker for DH?
(Looking for Ig class and its target)
What HLA subtypes are most at risk? (2)
What should patients be checked for to ensure there is not a false negative result for these antibodies?
IgA antibodies directed against epidermal transglutaminase cause the cutaneous lesions in DH.
IgA anti–tissue transglutaminase (tTG) antibodies are considered the most sensitive and specific serologic marker for DH.
The disease had a genetic predisposition associated with human leukocyte antigens DQ2 and DQ8.
Total IgA should be tested to exclude false-negative results from serologic investigation and detect an IgA deficiency that can be found in some patients.
65
A 30-year-old man has a 1- to 2-cm papule on his upper arm, which he reported as swelling and changing color from blue to yellow.
What is the best diagnosis?
**Targetoid hemangioma**
Histologically they consist of ectatic vascular channels lined by 'hobnail' endothelial cells in the upper dermis. In the deep dermis, the vessels are small, dissect through collagen bundles, and are associated with hemosiderin. Fibrin thrombi can be present in the superficial vessels.
66
What constitutes "positivity" for PD-L1 by immunohistochemical studies?
PD-L1 positivity is defined as "**complete membranous positivity in the tumor cells**" (Figure).
67
What is the alternative name for epithelioid hemangioma?
What is the treatment?
Angiolymphoid hyperplasia with eosinophilia (ALHE)
Histologic examination shows a dermal blood vessel proliferation with a lymphocytic inflammatory infiltrate containing eosinophils. The endothelial cells are large and epithelioid but are otherwise not atypical.
Surgical excision is generally required
68
What two stains help identify a DSFP?
What is the approved chemotherapy for unresectable DFSPs?
What chromosomal translocation is involved in DFSP?
**Factor XIIIa negative**
**CD34+**
The tumor is positive for CD34 but negative for factor 13A, helping to differentiate it from a cellular fibrous histiocytoma.
For unresectable, recurrent, or metastatic tumors, **imatinib mesylate** is approved as systemic therapy by the Food and Drug Administration.
The **translocation (17;22)** seen in DFSP places the platelet-derived growth factor β-chain gene under the control of the collagen 1A1 promoter. Imatinib inhibits platelet-derived growth factor receptor.
69
A 57-year-old woman comes to you with a 3-cm pruritic nodule on her neck (Figure).
What is the most common therapeutic intervention for this lesion?
**Angiolymphoid hyperplasia with eosinophilia (ALHE)**
Histologically ALHE shows a well-circumscribed proliferation of blood vessels lined by plump endothelial cells with large nuclei and abundant eosinophilic cytoplasm. An associated stromal inflammatory infiltrate consisting of lymphocytes and scattered eosinophils is also identified. Surgical excision is the most common therapeutic intervention reported.
70
What does CD34 stain for?
Fibroblasts
71
In scleromyxedema, is the number of fibroblasts in the dermis increased or decreased? Will colloidal iron stain be positive or negative?
The histology is similar to what other condition related to gadolinium exposure?
In scleromyxedema, the number of fibroblasts is increased. A colloidal iron stain will be positive, revealing increased mucin in the upper and mid-reticular dermis.
In nephrogenic systemic fibrosis, most patients have a history of renal failure and exposure to gadolinium. This entity often shows similar histopathologic features to those of scleromyxedema, but the fibrosis is usually more prominent in the deeper dermis and subcutaneous septa.
72
True or false: in scleredema, the collagen bundles are swollen.
True
In scleredema, the collagen bundles are swollen, with a normal epidermis, often with effacement of rete ridges, thickened collagen bundles in the dermis with increased spaces between them, and interstitial mucin deposition between collagen bundles that can be demonstrated with Alcian blue, toluidine blue, and colloidal iron stain.
73
A 65-year-old patient with history of non-Hodgkin lymphoma, status post recent allogeneic bone marrow transplantation, develops widespread pruritic crusted and hyperkeratotic lesions. A skin biopsy was performed (Figure).
What is the diagnosis?
What do the arrows point out?
**Norwegian (crusted or keratotic) scabies**
Histologically, they present as massive orthokeratosis and parakeratosis with mites in all stages, psoriasiform hyperplasia, focal spongiosis, and exocytosis of neutrophils and eosinophils. Sometimes intraepidermal microabscesses are seen. The dermis demonstrates a superficial and deep infiltrate of chronic inflammatory cells with interstitial eosinophils.
**The presence of egg case remnants, which appear similar to pigtails, can be a helpful clue.**
74
A 53-year-old woman with a history of hepatitis C comes to you with a pruritic rash on the dorsal aspect of her feet (Figures A-C).
Necrolytic acral erythema
The histologic findings include psoriasiform hyperplasia with papillomatosis and dyskeratotic keratinocytes in the clinical setting of a psoriasiform plaque on the dorsal foot of a patient with history of hepatitis C. These findings are most consistent with necrolytic acral erythema.
75
A 64-year-old woman comes to clinic with a 1-year history of infiltrative grouped lesions on the left cheek and lateral eyebrows. A biopsy is performed; the histopathologic features are shown in the images below.
Folliculotropic mycosis fungoides
The low-power image shows a dense perifollicular and intrafollicular lymphocytic infiltrate (folliculotropism). The high-power image shows mucin within a follicle (follicular mucinosis). These findings are compatible with folliculotropic mycosis fungoides (FMF).
76
A 10-year-old girl comes to you with multiple yellowish papules on the lateral neck and antecubital fossae. A skin biopsy is performed (Figures A and B). Von-Kossa and Verhoeff-von Gieson stains highlighted calcified and fragmented elastic fibers in the dermis.
77
What stain could be used to identify all of the following?
Leishmania, Histoplasma, and Rickettsia
Giemsa
78
A 56-year-old woman presents for evaluation of xanthelasma-like lesions around the eyes. Infiltrated yellow plaques are present. In addition, she complains of bone pain, polyuria, polydipsia, and episodic hypotension. A PET-CT scan shows diffuse uptake and hypermetabolism on the long diaphysis of the bones. There is also retroperitoneal uptake and lymphadenopathy. A skin biopsy shows a histiocytic infiltrate in the dermis with prominent xanthomatized changes. Scattered Touton-type giant cells are noted. By immunohistochemistry, the histiocytes are positive for CD68, CD163, and BRAF V600E. They are negative for S100, CD1a, and langerin.
Which of the following is the most likely diagnosis?
Erdheim-Chester disease is an uncommon form of systemic histiocytosis associated in a high proportion of cases (76%) with BRAF V600E mutations, diabetes insipidus, and involvement of the bones (B). Xanthelasma-like lesions are typical of the disease. Necrobiosis is absent as opposed to cases of necrobiotic xanthogranuloma. The skin biopsies, when involved, show a dermal histiocytic infiltrate with xanthomatized changes.
79
PXE is an autosomal recessive disorder resulting from mutations fo what gene?
What extracutaneous problems may occur with PXE?
How does this present clinically and histologically?
ABCC6
Patients may have a history of cardiovascular conditions (hypertension, mitral valve prolapse, myocardial infarction), occular manifestations, and gastrointestinal hemorrhage.
The characterisic skin findings are yellowish papules and plaques with a "plucked chicken skin" appearance on the neck and flexural surfaces. Histologic findings include fragmented and calcified elastic fibers stained brown-black with Von Kossa stain.
80
Alizarin red stains what?
Cresyl violet stains what?
**Alizarin red** is a **calcium stain**.
**Cresyl violet** stains **amyloid deposits red**.
81
A 65-year-old man presents with a mass on his mid back that has been enlarging for several months. Biopsy shows a dense, nodular dermal lymphoid infiltrate that is separated from the epidermis by a grenz zone. Lymphoid cells formed irregular, nodular aggregates of enlarged follicle center-type cells, including a disorganized combination of centrocytes that show cleaved/irregular nuclear contours, and centroblasts, which are larger cells with more open chromatin and visible nucleoli.
What is the typical immunophenotype of primary cutaneous follicle center lymphoma?
CD20+, BCL6+, BCL2-, FOXP1-
Primary cutaneous follicle center lymphoma is a B-cell lymphoma derived from the follicle/germinal center B-cells. It expresses B-cell markers (CD19, CD20, CD22, CD79a, PAX-5) and follicle center markers (BCL6, less commonly CD10), but is usually negative for BCL2, FOXP1, and MUM1. While expression of BCL2 and CD10 may be seen in primary cutaneous follicle center lymphoma, the expression of both markers raises concern for a systemic/nodal follicular lymphoma secondarily involving the skin.
82
A middle-aged man with human immunodeficiency virus has numerous brown macules on the trunk. He feels well otherwise but is bothered by the appearance. The eruption has not responded to topical selenium sulfide lotion or the application of imidazole cream. A biopsy of one of the macules was performed (Figure).
Which of the following is the best diagnosis?
**Acquired epidermodysplasia verruciformis** occurs in patients with HIV as well as other types of immunodeficiency and may mimic pityriasis versicolor on clinical examination. Biopsy reveals large pale keratinocytes in the granular and spinous layers. There can be a prominent perinuclear halo. Keratohyaline granules of various shapes and sizes can be encountered.
83
A 37-year-old African-American woman with a history of systemic lupus erythematosus on hemodialysis developed nonhealing ulcers on the buttocks three months ago. The image obtained is shown. Clinical examination reveals well-demarcated ulcerations with granulation tissue and undermined edges. The patient denies any fever or chills and overall feels well. Tissue culture for bacteria is negative. A biopsy was performed. The findings are shown in the second image obtained.
What is the most likely cause of the patient’s ulceration?
**Cytomegalovirus (CMV) vasculitis**
Secondary vasculitis in lupus can be due to medications or infections. The histopathology image demonstrates characteristic cytomegalovirus (CMV) inclusions (owl’s eye nuclei) in the vascular endothelium (secondary vasculitis) (B).
84
What is Rowell syndrome?
Rowell syndrome is characterized by **erythema multiforme-like lesions in systemic lupus**, typically in middle-aged women.
85
An 85-year-old man is being evaluated for a rapidly growing red nodule on his chest. He otherwise feels well. A biopsy reveals neoplastic cells with hyperchromatic nuclei. Staining with cytokeratin 20 reveals the pattern shown (Figure).
Which of the following is the best diagnosis?
**Merkel cell carcinoma**
Merkel cell carcinoma presents as a dermal or subcutaneous tumor composed of neoplastic cells with hyperchromatic nuclei and indistinct cytoplasm. Frequent mitotic figures are evident and apoptotic nuclei may be encountered. **A cytokeratin 20 stain is typically associated with a paranuclear dot-like pattern as seen in this case.** CD56, neuron-specific enolase, as well as variable chromogranin, CD117, and synaptophysin staining are typically positive in most cases. **A thyroid transcription factor (TTF) 1 stain is negative in most cases and helps exclude a diagnosis of a metastatic lung carcinoma**, which can otherwise be associated with identical findings on routine histologic evaluation.
86
Which of the following is the typical immunophenotype for primary cutaneous CD8+ aggressive, epidermotropic, cytotoxic T-cell lymphoma?
**CD8+, TIA-1+, TCRBF1+, CD5-**
Sometimes referred to as “Berti’s lymphoma.”
In addition, unlike mycosis fungoides, **this lymphoma is more likely to show expression of CD7 and loss of CD5.**
The immunophenotype described in answer A is compatible with primary cutaneous g-DT-cell lymphoma. The immunophenotype described in answer C would be more typical of CD8+ mycosis fungoides than Berti’s lymphoma. Answer D is compatible with ALK+ systemic anaplastic large cell lymphoma. Answer E could be seen in adult T-cell lymphoma/leukemia, an HTLV-1 related neoplasm.
87
A 56-year-old woman has a red nodule on the ear that developed following trauma to the site. In view of the lack of clinical response to corticosteroids a punch biopsy was taken: the biopsy shows a dermal infiltrate with a vague nodular pattern. Small, medium and large lymphocytes are positive in a background of plasma cells and eosinophils. A Ki67 shows a low (\<10%) proliferation index. Immunohistochemistry shows a mixture of T and B-cells. Frequent medium and large cells are positive for BCL-6, PD-1 and CXCL13.
On the basis of such findings, what is the most likely combination of pathologic diagnoses and clonality studies will be encountered?
Small to medium size CD4+ lymphoproliferative disorder; T-cell receptor clonal
Small to medium sized CD4+ lymphoproliferative disorder is an indolent provisional entity in the WHO that is characterized by a T-cell infiltrate with the expression of T-helper markers (BCL-6, CXL13, PD-1, ICOS) (E). Such lesions are invariably indolent. Additional staging procedures are not required for further evaluation. A rich background of B-cells is often noted, which can potentially mimic a CBCL.
Cutaneous marginal zone lymphoma does not show expression of BCL-6, CXCL13 or ICOS (A).
Unilesional mycosis fungoides is very rare and does not typically present in the face (B). A rich B-cell infiltrate is also not typical of mycosis fungoides.
Primary cutaneous follicle center lymphoma more typically manifests as a plaque (C). The lesions show a follicular or diffuse pattern. The neoplastic cells are B-cells with co-expression of BCL-6 and sometimes BCL-2. Immunoglobulin heavy is clonal in most cases.
Reactive lymphoid hyperplasia do not typically show an abundance of T-cells with TFH markers (D).
88
**Granular parakeratosis** may be due to a defect in the processing of what?
A defect in **processing of profilaggrin to filaggrin** is suspected and may account for the prominent keratohyaline granules noted in the stratum corneum.
89
A 92-year-old woman develops three large nodules on the left leg. She reports that the nodules seemed to develop overnight. She has otherwise felt well. Immunohistochemical staining reveals strong expression of Bcl-2 and MUM1 in neoplastic cells (Figure).
Which of the following is the best diagnosis?
What are two possible treatments?
**Primary cutaneous diffuse large B-cell lymphoma, leg type**
The immunohistochemical staining with **strong expression of Bcl-2 and MUM1** in neoplastic cells is characteristic of **primary cutaneous diffuse large B-cell lymphoma, leg type**. Cohesive sheets of centroblasts and immunoblasts are evident. The location on the lower legs is typical for primary cutaneous large B-cell lymphoma of the leg type. About one-quarter of all non-Hodgkin lymphoma cases present in an extranodal location without systemic involvement, with the skin being a common site. **Fluorescence in situ hybridization reveals translocations of the MYC, Bcl-6, and IGH genes.**
Treatment with **rituximab** is often helpful especially when **combined with an anthracycline-based chemotherapeutic agent**. Unfortunately, many patients have relapses.
90
A 27-year-old man came to the dermatology office with a pruritic hyperpigmented patch on the back. On histology, there are small deposits of amorphous pink material within the papillary dermis.
Which of the following special stains would be most helpful in confirming the diagnosis in this case?
**Congo red**
The histologic and clinical findings are compatible with macular amyloidosis. Congo red stains amyloid green under polarized light. Orcein stains collagen pink and elastic tissue dark brown. von Kossa stains calcium black. Fontana stains melanin black, but does not specifically stain melanocytes. von Gieson stains elastic tissue black.
91
A 42-year-old woman gradually developed a crusted lesion on the left medial thigh, an image of which is shown (Figure).
Which of the following is the best diagnosis?
**Hemangioma with papillary endothelial hyperplasia (Masson tumor)**
Intravascular papillary endothelial hyperplasia (Masson tumor) can occur within a dilated vascular space or in a preexisting hemangioma as in this case. Endothelial cells line vascular spaces and erythrocytes are noted within some of the vascular spaces.
92
A 37-year-old man with a long-standing history of mycosis fungoides developed multiple, ulcerative tumors.
Transformation to a large cell lymphoma (large cell transformation) in mycosis fungoides is defined as:
**\>25% of neoplastic T-cell are FOUR times the size of a normal lymphocyte**
In CD30+ cases, the histopathologic differential diagnosis includes anaplastic large cell lymphoma (A); however, a clinical history of mycosis fungoides helps to exclude anaplastic large cell lymphoma in favor of CD30+, transformed mycosis fungoides. They may be CD30+ or CD30- (B). In diffuse large B-cell lymphoma, large cells are defined as twice the size of a normal lymphocyte (D) and form diffuse sheets of cells. While loss of CD7 by a large percentage of lymphocytes may help to establish a diagnosis of mycosis fungoides, this features is not used to determine large cell transformation (E).
93
A 40-year-old man with weight loss and kidney failure develops dusky nodules on the lower legs. A biopsy of one of the nodules was performed; the histopathologic features are shown in the image below.
Which of the following is the best diagnosis?
**Polyarteritis nodosa**
## Footnote
The biopsy specimen reveals a medium-sized artery with transmural inflammation. The segmental transmural inflammation of muscular arteries characterizes biopsies of polyarteritis nodosa. Polyarteritis does not involve veins. The infiltrate consists of polymorphonuclear leukocytes and mononuclear cells. Patients typically have associated fatigue, weight loss, weakness, fever, and arthralgias.
94
A 48-year-old man is being evaluated for multiple confluent plaques on the buttock area. The areas are pruritic and symmetrically distributed. A biopsy specimen is shown (Figure).
Which of the following is the best diagnosis?
**Porokeratosis ptychotropica**
Porokeratosis ptychotropica typically presents as multiple confluent plaques. Satellite areas of involvement may be noted and the lesions are often pruritic. Perianal involvement and symmetrical involvement of the buttocks is typical. Histopathology reveals multiple cornoid lamellae. Porokeratosis ptychotropica differs from porokeratosis of Mibelli in that the cornoid lamellae are multiple and somewhat irregularly distributed compared with the peripheral cornoid lamellae typical of porokeratosis of Mibelli.
95
A 72-year-old Caucasian man comes to clinic with a violaceous nodule on his scalp. Histologic findings are shown in the first image obtained. High power view demonstrates predominantly small lymphocytes. Immunohistochemistry for CD21 exhibited markedly enlarged, often disrupted and fused follicle dendritic cell networks (shown in the second image obtained). Lesional cells are diffusely positive for CD20, PAX-5, CD10, BCL-6, and BCL-2. MUM-1 is negative.
What is the best diagnosis?
**Cutaneous involvement by nodal follicle center cell B-cell lymphoma**
The histology shows dense nodular lymphocytic aggregates composed of small-sized lymphocytes with a bottom-heavy arrangement. Follicle center cell B-cell lymphoma (FCC-BCL) typically stains with BCL-6 and not BCL-2, however, **the combination of BCL-6 and BCL-2 expression is highly suspicious for secondary cutaneous involvement by systemic (nodal) FCC-BCL**. P**rimary FCC-BCL typically only stains with BCL-6, but _not_ BCL-2**.
OTOH, Marginal zone lymphoma (MZL-BCL) shows positivity with BCL-2, but not BCL-6.
96
An 87-year-old woman presents with multiple, rapidly growing violaceous lesions on her left lower leg (Figure 1). A biopsy demonstrates diffuse sheets of large lymphoid cells with rounded nuclear contours, open chromatin and visible nucleoli (Figure 2A, B).
**CD20+, BCL2+, FOXP1+, MUM1+**
**Primary cutaneous diffuse large B-cell lymphoma, leg type** is composed of sheets of large B-cells and is limited to the skin at diagnosis.
These large, round cells include centroblasts and immunoblasts, and differ from the irregular nuclei of centrocytes that are seen in primary cutaneous follicle center lymphoma. The neoplastic cells in primary cutaneous diffuse large B-cell lymphoma, leg type express BCL2, MUM1, IgM, and forkhead box protein 1 (FOX-P1) (B). BCL6 is common (68% of cases), but CD10 expression is not.
97
Which are nuclear or cytoplasmic stains?
Melan-A, MiTF, and SOX-10
Melan-A → cytoplasmic stain
MiTF and SOX-10 → nuclear stains
98
A 55-year-old man comes to clinic with a lesion that has been previously biopsied and reported as an atypical melanocytic proliferation.
Detecting mutations in which of the following genes is helpful in differentiating melanoma from benign nevi?
*hTERT*
Cancer-specific driver mutations are believed to be pivotal not only for the proliferation and survival of malignant cells but also for the initial expansion of benign and premalignant clones. Accordingly, driver mutations are found at high frequency in conventional nevi (BRAF), congenital nevi (NRAS), Spitz nevi (HRAS), blue nevi (GNAQ and GNA11), and dysplastic nevi (BRAF, CDKN2A) besides their malignant counterparts. In contrast, highly recurrent mutations within the promoter of the human telomerase reverse transcriptase (hTERT) gene have been found in numerous malignant malignancies, including human melanoma (~70%) but not in benign lesions). Recurrent hTERT promoter mutations enhance hTERT mRNA transcription, which leads to increased hTERT activity and telomere lengthening, a molecular prerequisite for malignant transformation.
99
Bullous tinea pedis is most commonly caused by Trichophyton \_\_\_\_\_, and bullous tinea corporis is most commonly caused by Trichophyton \_\_\_\_\_.
Bullous tinea pedis is most commonly caused by ***Trichophyton mentagrophytes***, and bullous tinea corporis is most commonly caused by ***Trichophyton rubrum***.
100
Which immunohistochemical marker can be helpful in distinguishing lupus erythematosus from other inflammatory dermatoses?
**CD123**
Plasmacytoid dendritic cells (pDCs) are the main cellular source of type I interferon (IFN-I) and play a central role in the pathogenesis of lupus erythematosus. Immunohistochemical detection of CD123+ pDC aggregates (ie, perivascular, periadnexal, subepidermal) is a useful tool to differentiate lupus from other inflammatory dermatoses, including lichen planus, rosacea, lichen planopilaris, or subcutaneous panniculitis-like T-cell lymphoma (C). CD56 is an NK-cell marker (A), CD117 (C-KIT) highlights mast cells (B), CD163 detects macrophages (D), and CD207 (Langerin) is specific for Langerhans cells (E).
101
A skin biopsy from a 10-year-old boy shows the features in the first image obtained. Lesional cells are highlighted by CD1a.
Which additional immunohistochemical stains may be helpful in evaluating this patient?
**CD207 (Langerin); G: S-100 and I:VE1 for BRAF V600E mutation**
## Footnote
Langerhans cell histiocytosis (LCH) is characterized by the clonal expansion of CD1a+ CD207 (Langerin)+ S100+ Langerhans-type histiocytes (D, G). LCH cells appear to derive from bone marrow-derived immature myeloid dendritic cells and not from epidermal Langerhans cells. BRAF V600E mutation has been observed in a significant proportion of cases, predominantly younger patients without association with disease site or stage . The VE1 immunohistochemical stain identifies this specific mutation (I). CD5 is a T-cell marker (A); CD20 is a B-cell marker (B); CD138 is a plasma cell marker (C). Melan-A and Sox-10 are melanocyte markers (E, H). NSE is a marker of neural derivation (F).
102
Alopecia with “footprint in the snow” pattern is characteristic of what form of hair loss?
Pseudopelade of Brocq
A biopsy would show scarring alopecia including concentric perifollicular fibrosis, loss of sebaceous glands, and, eventually, loss of follicular units that are replaced by scar (end-stage scarring alopecia).
103
A 30-year-old woman comes to clinic with hair loss. A biopsy is performed. The findings are shown in the images obtained.
Given the histologic findings, what is the most likely clinical presentation in this case?
Patchy hair loss containing hairs with varying lengths
The images obtained depict a collapsed inner root sheath without hair shaft and a distorted narrow-caliber hair shaft (trichomalacia) with a pigment cast. These findings are pathognomonic for trichotillomania. Clinically, irregularly shaped patches of alopecia and hair shafts with varying lengths are characteristic (C).
104
A 48-year-old man presents with an 8 mm, asymptomatic pink papule on the scrotum of unknown duration. A shave biopsy is performed on the lesion and the histologic features are shown in the low and high power photomicrographs below.
Based on the images shown, what is the best diagnosis?
**Verruciform xanthoma**
The photomicrographs show digitate epidermal hyperplasia, overlying parakeratosis, and cornified and dyskeratotic cells within the surface crypts that appear to “float” into the scale. Numerous foamy macrophages are present within the papillary dermis, a feature which may be highlighted by a CD68 immunostain if necessary. The histologic findings are compatible with a verruciform xanthoma. Verruciform xanthoma is of unknown etiology, but may be related to minor trauma. It most commonly occurs on oral mucosae or anogenital skin. Although not seen in this example, the parakeratotic scale may have an orange hue on routine histology.
105
A five-year-old girl has multiple pedunculated and flat-topped papules on the dorsal hands with a predominant periungual location (Figure 1). Histopathology is shown (Figure 2).
Which of the following is the BEST diagnosis?
Will this be positive or negative for the following: CD68, factor XIIIa, S-100, and CD1a?
**Multicentric reticulohistiocytosis**
Multicentric reticulohistiocytosis is a very rare and aggressive condition characterized by skin lesions, mucosal lesions, and arthritis. It usually arises in middle-aged women. Histologic examination shows diffuse infiltration of the dermis by histiocytic cells and scattered multinucleated giant cells. The lesional cells demonstrate a dense pink cytoplasm, variously referred to as “oncocytic” or “ground glass.” The ground glass cytoplasm is periodic acid–Schiff positive. **Immunostaining shows cell positivity for CD68 and factor 13a and negativity for S-100 and CD1a.**
106
Is JXG negative or positive for CD68 and factor XIIIa?
Immunostaining shows cell **positivity for CD68 and factor 13a**.
107
A 22-year-old woman presents with a solitary asymptomatic red plaque on the medial breast. A punch biopsy is performed with the histopathologic features shown in the low and high power photomicrographs below.
Which immunohistochemical stain is the most appropriate to confirm the diagnosis?
**S100**
At low power magnification, there is a diffuse dermal infiltrate creating a pattern of alternating dark and pale staining areas. At high power, the infiltrate is composed of large epithelioid histiocytes with abundant pale cytoplasms, lymphocytes, plasma cells, and neutrophils. Lymphocytes and neutrophils are present within the cytoplasms of the histiocytes, a phenomenon referred to as emperipolesis. Altogether, the histologic findings are compatible with a cutaneous manifestation of sinus histiocytosis (Rosai-Dorfman disease). The characteristic histocytes of Rosai-Dorfman disease show strong diffuse staining for S100, a result that can be particularly helpful when emperipolesis is subtle or the biopsy sample is small.
MART-1/Melan-A, Factor XIIIa, or CD1a would not help confirm the diagnosis as Rosai-Dorfman stains negative for these marker. CD68, while positive in Rosai-Dorfman, is a nonspecific marker of histiocytes.
108
Which of the following favor a diagnosis of lupus panniculitis over subcutaneous panniculitis T-cell lymphoma?
**B-cell follicles**
Lupus panniculitis can be extremely challenging to differentiate from subcutaneous panniculitis-like T-cell lymphoma, and some patients may have both diseases. Both entities may display a lobular lymphocytic infiltrate with lymphocytes rimming fat cells (F) associated karyorrhexis and fat necrosis. However, lupus is more likely to show epidermal atrophy, interface changes with thickened basement membrane, mucin, follicular plugging, hyaline lipomembranous change, and a mixed hematolymphoid infiltrate including aggregates of plasmacytoid dendritic cells and plasma cells, and B-cell follicles (A). In addition, it is uncommon for lupus panniculitis to be associated with significant cytologic atypia, a clonal T-cell population (B), loss of pan T-cell markers (D), or hemophagocytic lymphohistiocytosis (C).
109
A 65-year-old man presents with tender, violaceous nodules on the lower extremities. A punch biopsy is performed on one lesion and the histologic features are shown in the low and high power photomicrographs.
Based on the images shown, what is the best diagnosis?
**Pancreatic panniculitis**
The photomicrographs show a large focus of robust fat necrosis, deposition of stippled basophilic material compatible with early calcification and numerous ghost cells characterized by central amorphous/granular debris rimmed by an eosinophilic membrane, findings that are compatible with pancreatic panniculitis. Although not seen in this example, there may also be an associated acute and chronic inflammatory infiltrate.
Calciphylaxis is characterized by variably apparent calcifications within small vessels in the subcutaneous tissue that are plugged with fibrin thrombi. A Von Kossa stain may help highlight the calcium. Usually, there is necrosis of the epidermis and/or dermis.
110
A 40-year-old woman comes to clinic with an asymptomatic umbilicated keratotic nodule on the face. The lesion is biopsied. The findings are shown in the image obtained.
What is the best diagnosis?
**Warty dyskeratoma**
Warty dyskeratoma is characterized by a central cup-shaped invagination, although cystic, nodular, and folliculocentric patterns have been reported. Within the deeper portion of the lesion villi are present. These villi project upward toward the surface and are lined by keratinocytes that show suprabasal acantholysis with cleft formation. Dyskeratosis is present with the formation of corp ronds and grains. Corp ronds are present within the upper stratum spinosum and stratum corneum and have a basophilic central pyknotic nucleus that is surrounded by a clear halo. Surrounding the halo is basophilic dyskeratotic material. Grains are smaller and resemble parakeratotic nuclei. Dyskeratotic material also surrounds the grains and can be either eosinophilic or basophilic. Grains are commonly seen in the stratum corneum.
111
Is stromelysin 3 is positive or negative in dermatofibroma?
**Stromelysin 3 _positive_**
112
Which of the following immunophenotypic findings are compatible with a diagnosis of **primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder**?
**CD3+, CD4+, PD-1+, CD7-**
Primary cutaneous small-medium pleomorphic T-cell lymphoma is an uncommon lymphoma that typically presents as a solitary, slowly enlarging and persistent nodule on the head, neck, or upper trunk. It is an uncommon lymphoma, but is a frequent histopathologic consideration in biopsies showing a dense, dermal lymphoid infiltrate without epidermotropism. It is characterized by a CD4-predominant T-cell infiltrate that expresses markers compatible with the immunophenotype of T-cells in the germinal/follicle center (also known as a follicular helper T-cell phenotype). These markers include BCL6, PD1, and CXCL13. In addition, this lymphoma often shows loss of one or more pan T-cell markers (ie, CD2, CD5, CD7) and a clonal T-cell population.
113
A 65-year-old man comes to clinic with the lesion shown in the image shown. A biopsy was performed. The pathology report returned a diagnosis of malignant melanoma with a Breslow depth of 0.9 mm without ulceration and two mitoses per high power field.
What is the pathological stage according to the 2018 American Joint Committee on Cancer staging system?
**Stage pT1b**
Primary melanoma thickness (Breslow depth) and ulceration continue to define T category strata. The definitions of T1a and T1b have been revised so that T1a melanomas include those \<0.8 mm without ulceration while T1b melanomas include those 0.8-1 mm with or without ulceration and those \<0.8 mm with ulceration. Mitotic rate is no longer a T1 category criterion but should be documented for all invasive primary melanomas. As this lesion had a reported Breslow depth of 0.9 mm and absent ulceration, the correct answer is Stage pT1b.
114
A 55-year-old woman from Brazil presents with a one year history of generalized erythroderma. Laboratory reveals a lymphocytosis with the presence of abnormal cells in the blood and hypercalcemia. A punch biopsy shows an epidermotropic infiltrate with a predominance of CD4+ T-cells over CD8+ cells. Diffuse expression of CD25 is noted among the T-cells, in addition to loss of CD7 and CD26 on flow cytometric evaluation of the blood.
Which of the following diagnosis is favored?
**Adult T-cell leukemia/lymphoma**
Adult T-cell leukemia / lymphoma (ATLL)is one of the most common forms of T-cell leukemia in Asia and central areas of South America (C). The patient originally comes from Brazil, which is one of the endemic areas of this neoplasm. Clinically, some patients can present with erythroderma, similarly to Mycosis fungoides/Sezary syndrome (MF/SS). The laboratory finding of hypercalcemia suggests the presence of lytic bone lesions, a feature that is typical of ATLL. The phenotype is also typical for ATLL: CD4+, CD7-, CD26- and CD25+. The next best step is to perform a serologic evaluation for the presence of HTLV-1.
Cutaneous g-∆ T-cell lymphoma typically presents as ulcerated lesions in the trunk and extremities and not erythroderma (E). In addition, this is a CD56+, CD4-, CD8- process.
Mycosis fungoides/Sezary syndrome does not typically present with hypercalcemia (A). The strong and diffuse expression of CD25 is also not typical.
