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Anatomic pathology > Lymph Nodes > Flashcards

Flashcards in Lymph Nodes Deck (343):
1

Reactive follicular hyperplasia in rheumatoid arthritis: Histology.

Following treatment with gold salts: Scattered non-birefringent crystals with foreign-body reaction.

2

Reactive follicular hyperplasia in Sjögren's syndrome: Histology.

There may be aggregates of monocytoid B cells.

3

Reactive follicular hyperplasia in autoimmune disease: Proliferation.

Ki-67 stains more than 90% of cells in reactive germinal centers and about 5% in interfollicular areas.

4

Reactive follicular hyperplasia in autoimmune disease: PCR.

May show clonality of B cells, but this finding alone is not diagnostic of malignancy.

5

Syphilitic lymphadenopathy: Site.

Inguinal lymph nodes.

6

Syphilitic lymphadenopathy: Histology (3).

Thickening of capsule.

Marked plasmacytic infiltration.

Vasculitis.

7

Syphilitic lymphadenopathy: Locations of spirochetes (3).

Endothelial cells.

Blood vessels.

Germinal centers.

8

Early EBV lymphadenitis: Histology.

Expanded paracortex with many immunoblasts.

9

Follicular lymphoma: Histology of capsule.

Thickened and may appear split due to follicular proliferation.

10

Mantle-cell lymphoma: Association autoimmune diseases (2).

Sjögren's syndrome.

Hashimoto's thyroiditis.

11

Main cellular components of the ___.

A. Cortex.
B. Paracortex.
C. Medulla.
D. Sinuses.

A. B cells.

B. T cells.

C. Plasma cells.

D. Histiocytes.

12

Cytomegalovirus lymphadenitis: Early histology (2).

Reactive follicular hyperplasia.

Hyperplasia of monocytoid B cells.

13

Immunohistochemistry: All B lymphocytes (3).

Positive: CD20, CD79a, PAX5.

14

Immunohistochemistry of B cells ___.

A. Within the germinal centers (2,1).
B. Outside the germinal centers (1,2).

A. Positive: CD10, Bcl-6; negative: Bcl-2.

B. The inverse pattern.

15

Immunohistochemistry:

A. Follicular dendritic cells.
B. Antigen-presenting interdigitating dendritic cells.

A. Positive: CD21, CD23.

B. Positive: S100.

16

Reactive follicular hyperplasia in autoimmune disease: General histology (3).

Florid reactive follicular hyperplasia.

Sinus histiocytosis.

Markedly increased plasma cells in paracortex and medulla.

16

Cytomegalovirus lymphadenitis: Later histology (2).

Paracortical hyperplasia with immunoblasts.

Hypervascularity.

17

Cytomegalovirus lymphadenitis: Histology in the immunocompromised.

There may be necrosis.

18

Cytomegalovirus lymphadenitis: Best place to look for viral cytopathic effect.

In the collections of monocytoid B cells.

19

Cytomegalovirus lymphadenitis: Immunophenotype.

Infected cells may express CD15 (and possibly cause confusion with Hodgkin's lymphoma).

20

Toxoplasma lymphadenitis: Histology (3).

Follicular hyperplasia.

Hyperplasia of monocytoid B cells.

Aggregates of epithelioid histiocytes in lymphoid follicles.

21

Toxoplasma lymphadenitis: Presentation.

Bilateral cervical lymphadenopathy, non-tender.

22

Toxoplasma lymphadenitis: Demonstration of organism (2).

Immunohistochemistry: Usually not helpful.

Serology: Better.

23

Toxoplasma lymphadenitis vs. leishmania lymphadenitis (2).

Leishmania lymphadenitis:

- Granulomas with or without necrosis.
- Amastigotes may be seen.

24

Toxoplasma: Reactivation of infection in AIDS patients.

Usually as encephalitis instead of lymphadenitis.

25

HIV-related lymphadenopathy: Presentation (2).

Mainly involves axillary, cervical, and occipital nodes.

Lymph nodes decrease somewhat in size after acute presentation.

26

HIV-related lymphadenopathy: Criteria of persistent generalized lymphadenopathy (3).

More than 3 months.

At least 2 noncontiguous nodal sites.

No other explanation.

27

HIV-related lymphadenopathy: Early histology of follicles (4).

Large, irregular germinal centers.

Many mitotic figures and tingible-body macrophages in the germinal centers.

Follicle lysis.

Attenuated mantle zones.

28

HIV-related lymphadenopathy: Other early histology (2).

Paracortex: Granulocytes, conspicuous vessels.

Sinuses: Histiocytosis, erythrophagocytosis.

29

HIV-related lymphadenopathy: Later histology (3).

Small, atrophic, hyalinized follicles.

Paracortex: More histiocytes and plasma cells; fewer lymphocytes.

More blood vessels.

30

HIV-related lymphadenopathy: Immunohistochemistry (3).

Reactive germinal centers: Many CD8-positive lymphocytes.

Interfollicular area: Fewer CD-positive lymphocytes; many S100-positive IDCs.

Advanced disease: Absence of CD21- and CD23-positive FDCs.

31

Kimura's disease: Classic patient.

East Asian male with painless subcutaneous masses and lymphadenopathy of head and neck.

32

Kimura's disease: Internal site.

Salivary gland (in 40% of patients).

33

Kimura's disease: Laboratory findings (2).

Eosinophilia.

Elevated serum IgE.

34

Kimura's disease: Histology (4).

Reactive follicular hyperplasia.

Many eosinophils.

Hypervascularity.

Eosinophilic proteinaceous deposits (IgE) in the germinal centers.

35

Kimura's disease vs. drug-related lymphadenopathy (2).

Drug-related lymphadenopathy:

- Paracortical proliferation of immunoblasts.
- There may or may not be follicular hyperplasia.

36

Kimura's disease vs. angiofollicular hyperplasia with eosinophilia (2).

Angiofollicular hyperplasia with eosinophilia:

- Typically affects middle-aged white women.
- Eosinophilic microabscesses are unusual.

37

Causes of increase in IgG4-positive lymphocytes (4).

IgG4-related disease.

Carcinoma.

Lymphoma.

Others.

38

IgG4-related lymphadenopathy: Classic presentation.

Autoimmune pancreatitis.

39

IgG4-related lymphadenopathy: Other frequently involved organs (5).

Kidney.

Lung.

Liver.

Gallbladder.

Ocular adnexa.

40

IgG4-related lymphadenopathy: Types.

I: Multicentric Castleman's disease-like.

II: Follicular hyperplasia.

III: Paracortical expansion.

IV: Progressive transformation of germinal centers.

V: Inflammatory pseudotumor-like.

41

IgG4-related lymphadenopathy: Histology of type I (3).

Hyperplastic and atrophic follicles.

Interfollicular vascular proliferation.

Eosinophilia.

42

IgG4-related lymphadenopathy: Histology of type II (2).

Interfollicular and paracortical plasmacytosis.

Eosinophilia.

43

IgG4-related lymphadenopathy: Histology of type III (2).

Prominent high-endothelial venules.

Expansion of paracortex by various lymphocytes and eosinophils.

44

IgG4-related lymphadenopathy: Histology of type IV (2).

Enlarged follicles with expanded mantle zones.

Scattered interfollicular plasma cells.

45

IgG4-related lymphadenopathy: Clonality.

Stains for kappa and lambda light chains demonstrate polytypic plasma cells.

46

IgG4-related lymphadenopathy: Quantification (2).

Ratio of IgG4 to IgG is more than 40%.

Thee must be more than 100 IgG4-positive plasma cells in at least 3 hpf.

47

IgG4-related lymphadenopathy: Laboratory findings (3).

High serum IgG4.

Normal IL-6.

Normal CRP.

48

IgG4-related lymphadenopathy vs. inflammatory pseudotumor.

Inflammatory pseudotumor: No increase in IgG4-positive plasma cells.

49

IgG4-related lymphadenopathy: Putative causes.

Chronic infection.

Autoimmune disease.

50

IgG4-related lymphadenopathy: Treatment.

Patients respond well to steroids.

51

IgG4-related lymphadenopathy: Main histologic feature in non-lymphoid organs.

Sclerosis.

52

IgG4-related lymphadenopathy: Histology of type V.

Lymph node is focally replaced by fibrous tissue containing plasma cells and lymphocytes.

53

Progressive transformation of germinal centers: Typical patient.

Child or young adult with a single enlarged lymph node.

54

Progressive transformation of germinal centers: Histology

Massively expanded mantle zone with loss or fragmentation of the germinal center.

Typically follicular hyperplasia in the background.

55

Progressive transformation of germinal centers: Immunohistochemistry.

Mantle zones are reactive for Bcl-2 and IgD.

Germinal centers contain increased CD57+ cells.

56

Progressive transformation of germinal centers: Flow cytometry.

CD4+/CD8+ T lymphocytes may be detected.

57

Progressive transformation of germinal centers: Relation to NLP-HD.

PTGC may rarely precede, follow, or coexist with NLP-HD.

58

Infectious mononucleosis: Pattern of reactive hyperplasia.

Paracortical.

59

Infectious mononucleosis: Histology.

Expansion of paracortex by small, medium-sized, and large immunoblasts.

Increased mitotic activity.

Necrosis sometimes.

60

Infectious mononucleosis: Immunohistochemistry (2,1,2).

Positive: CD20, Mum-1.

Variable: CD30.

Negative: CD10, CD15.

61

Infectious mononucleosis: Molecular study.

In-situ hybridization for EBV (EBER).

62

Infectious mononucleosis vs. CMV lymphadenitis (2).

CMV lymphadenitis:

- IHC demonstrates presence of CMV.
- EBER negative.

63

Herpes simplex lymphadenitis: Presentation (2).

Localized or generalized.

Usually painful.

64

Herpes simplex lymphadenitis: Histology (3).

Paracortical hyperplasia with many immunoblasts.

Multifocal necrosis with neutrophils.

Typical viral cytopathic effect.

65

Herpes simplex lymphadenitis vs. other necrotizing lymphadenitides.

HSV lymphadenitis: No granulomas associated with the necrosis.

66

Dermatopathic lymphadenitis: Histology (2).

Paracortical expansion, diffuse or nodular.

Many interdigitating dendritic cells, Langerhans' cells, and histiocytes that contain melanin.

67

Dermatopathic lymphadenitis vs. mycosis fungoides (2).

Mycosis fungoides:

- Atypical lymphocytes present singly, in clusters, or in large aggregates.
- PCR may be needed to exclude rearrangement of the T-cell receptor.

68

Dermatopathic lymphadenitis vs. Langerhans' cell histiocytosis.

LCH: Langerhans' cells fill the sinuses and are accompanied by eosinophils, neutrophils, plasma cells, and histiocytes.

69

Drug-related lymphadenopathy:

A. Timing.
B. Involved nodes.

A. Within 2 to 8 weeks after exposure to the drug.

B. Cervical lymph nodes or all nodes.

70

Drug-related lymphadenopathy: Causes (2).

Antiepileptics.

Allopurinol.

71

Drug-related lymphadenopathy: Histology.

Paracortical expansion with immunoblasts and eosinophilia.

Immunoblasts may form large aggregates.

72

Drug-related lymphadenopathy: Most powerful tool for diagnosis.

Clinical history of exposure to implicated drug.

73

Rosai-Dorfman disease: Typical patient.

Child or young adult with bilateral cervical lymphadenopathy.

74

Rosai-Dorfman disease: Other possible signs and symptoms

Fever.

Weight loss.

Leukocytosis.

Anemia.

Elevated ESR.

75

Rosai-Dorfman disease: Histology (2).

Histiocytes markedly expand the sinuses.

Small lymphocytes and abundant plasma cells accompany the histiocytes.

76

Rosai-Dorfman disease: Cytology

Histiocytes . . .

- Nucleus: Round, with single nucleolus.
- Cytoplasm: Abundant, eosinophilic.
- Emperipolesis, especially of lymphocytes.

77

Rosai-Dorfman disease: Immunohistochemistry (4,2).

Positive: S100, CD14, CD68, CD163.

Negative: CD1a, langerin.

78

Lymph nodes draining prosthetic implants: Histology.

Sinus histiocytes containing coarse refractive matter.

79

Whipple's disease: Initial presentation.

Migratory arthralgia.

80

Whipple's disease: Histology.

Histiocytes distend the sinuses.

Lipogranulomas.

Non-necrotizing granulomas sometimes.

81

Whipple's disease: Special stains (2).

Positive (histiocytes): PAS.

Negative: AFB.

82

Whipple's disease: Best site of biopsy.

Small intestine.

83

Whipple's disease: Ancillary studies (2).

Electron microscopy.

PCR of tissue, stool, or saliva.

84

Lymphadenopathy due to deposition of endogenous lipid material: Sites.

Nodes of porta hepatis.

Celiac lymph nodes.

85

Lymphadenopathy due to deposition of endogenous lipid material: Causes (5).

Mineral oil.

TPN.

Cholesterol.

Fat embolism.

Fat necrosis.

86

Lymphadenopathy due to deposition of endogenous lipid material: Histology (3).

Vacuolated sinus histiocytes.

Extracellular spaces.

Giant cells.

87

Lymphadenopathy due to deposition of endogenous lipid material: Special stain.

Negative: PAS.

88

Kikuchi's disease: Synonym.

Histiocytic necrotizing lymphadenitis.

89

Kikuchi's disease: Typical patient.

Young Asian woman.

However, the disease can affect either sex and any age or ethnic group.

90

Kikuchi's disease: Typical presentation.

Cervical lymphadenopathy and fever.

91

Kikuchi's disease: Histologic phases.

Proliferative.

Necrotizing.

Resolution.

92

Kikuchi's disease: Histology of the proliferative phase (3).

Patchy nodal disease.

Paracortical expansion with immunoblasts, small lymphocytes, plasmacytoid dendritic cells, histiocytes.

Single-cell necrosis and granular débris.

93

Kikuchi's disease: Histology of the necrotizing phase (4).

Extensive necrosis with karyorrhexis.

Immunoblasts and histiocytes surround necrosis.

Histiocytes with crescentic nuclei.

No neutrophils.

94

Kikuchi's disease: Histology of the resolution phase.

Many foamy macrophages.

95

Kikuchi's disease: Immunohistochemistry.

Plasmacytoid dendritic cells are reactive for CD123.

Very few B cells outside the germinal centers.

96

Kikuchi's disease: Relationship to systemic lupus erythematosus (2).

Similar histologic features.

Some patients with Kikuchi's disease develop lupus.

97

Kikuchi's disease: Prognosis.

Usually self-limiting.

98

Lymphadenitis of Kawasaki's disease: Histology (3).

Widespread necrosis with many neutrophils.

Fibrin thrombi in small vessels.

Arteritis with fibrinoid necrosis.

99

Lymphadenitis of systemic lupus erythematosus: Presentation (2).

Lymph nodes are soft and nontender.

Occurs at the onset of the disease or during an exacerbation.

100

Lymphadenitis of systemic lupus erythematosus: Histology (5).

Edema, hemorrhage, and necrosis surrounded by histiocytes and immunoblasts.

May show many plasma cells.

May show hematoxylin bodies.

May show the Azzopardi phenomenon.

May show marked follicular hyperplasia.

101

Tuberculous lymphadenitis: Most common site.

Cervical lymph nodes.

102

Tuberculous lymphadenitis: Causes of abdominal disease (2).

Ingestion of sputum or milk infected by M. tuberculosis or M. bovis.

103

Tuberculous lymphadenitis: Type of granuloma.

Usually caseating but can be non-necrotizing.

104

Atypical mycobacterial lymphadenitis: Causes (5).

Mycobacterium avium complex.

M. kansasii.

M. scrofulaceum.

M. malmöense.

M. haemophilum.

105

Atypical mycobacterial lymphadenitis: Typical immunocompetent patient.

Child of 1 to 5 years.

106

Atypical mycobacterial lymphadenitis: Typical site.

Submandibular nodes.

107

Atypical mycobacterial lymphadenitis: Histology in the immunocompetent

Necrotizing and non-necrotizing granulomas with Langhans' -type giant cells.

108

Atypical mycobacterial lymphadenitis: Histology in the immunocompromised (2).

Poorly organized aggregates of histiocytes.

Rare: Mycobacterial pseudotumor consisting of foamy and spindled histiocytes.

109

Atypical mycobacterial lymphadenitis: Treatment in the immunocompetent.

Excision.

110

Leprosy: Countries of highest incidence.

Brazil.

Bangladesh.

India.

Indonesia.

Nigeria.

111

Lepromatous leprosy: Histology.

The paracortical area contains many foamy macrophages that are full of organisms.

112

Inflammatory pseudotumor of the lymph node: Infectious causes (3).

Atypical mycobacteria, Treponema pallidum, or EBV is detected in some cases.

113

Cat-scratch disease: Acquisition (3).

Flea bite.

Cat bite.

Cat scratch.

114

Cat-scratch disease: Presentation.

Tender nodes with overlying erythema.

115

Cat-scratch disease: Atypical presentation (3).

"B" symptoms.

Hepatosplenomegaly.

Abdominal lymphadenopathy.

116

Cat-scratch disease: Histology of the early stage (4).

Follicular hyperplasia.

Hyperplasia of monocytoid B cells.

Small foci of necrosis among monocytoid B cells.

Microabscesses in the germinal centers.

117

Cat-scratch disease: Histology of the late stage (2).

Large, stellate microabscesses.

Necrotizing granulomas with palisading histiocytes.

118

Bartonella henselae:

A. Typical locations in the lymph node (3).
B. Best stains (2).

A. Macrophages, endothelial cells, areas of necrosis.

B. Warthin-Starry, Steiner's.

119

Cat-scratch disease: Other methods of diagnosis (3).

Serology.

Culture.

PCR.

120

Cat-scratch disease: Prognosis in the immunocompetent.

Resolution in 2 to 6 months.

121

Cat-scratch disease: Prognosis in the immunocompromised (3).

Can lead to

- Widespread granulomatous inflammation.
- Bacillary angiomatosis.
- Bacillary peliosis.

122

Cat-scratch disease: Other bacteria that may cause histologically similar lymphadenitis (4).

Chlamydia trachomatis.

Francisella tularensis.

Haemophilus ducreyi.

Yersinia enterocolitica.

123

Sarcoidal lymphadenitis: Frequency.

Occurs in 40% of patients with sarcoidosis.

124

Sarcoidal lymphadenitis: Necrosis.

Not typical, but small foci of fibrinoid necrosis can be seen.

125

Sarcoidal lymphadenitis: Lymphoma that must be excluded.

Classic Hodgkin's lymphoma: Granulomas may be seen in affected nodes and in benign ones.

126

Brucellosis:

A. Histology of lymphadenitis.
B. Diagnosis (2).

A. May mimic tuberculous or sarcoidal lymphadenitis.

B. Culture, serology.

127

Castleman's disease: Types.

Hyaline-vascular: Most common.

Plasma-cell.

Multicentric.

128

Castleman's disease, hyaline-vascular type:

A. Typical patient.
B. Typical presentation.
C. Typical site.

A. Young adult.

B. Incidental finding.

C. Mediastinal lymph node.

129

Castleman's disease, plasma-cell type: Presentation.

Half of patients have

- Anemia.
- Increased ESR.
- Increased gamma globulins in the serum.
- Increased plasma cells in the bone marrow.

130

Castleman's disease, multicentric type: Typical patient.

Middle-aged or older adult.

131

Castleman's disease, multicentric type: Presentation (4).

Generalized peripheral lymphadenopathy.

Hepatosplenomegaly.

Frequent fevers.

Night sweats.

132

Castleman's disease, multicentric type: Associated malignancies (3).

Kaposi's sarcoma.

Hodgkin's lymphoma.

Non-Hodgkin's lymphoma.

133

Castleman's disease, multicentric type: Additional association.

Polyneuropathy.

Organomegaly.

Endocrinopathy.

Monoclonal gammopathy.

Skin changes.

134

Castleman's disease, hyaline-vascular type, histology:

A. Mantle zones (2).
B. Sinuses.
C. Interfollicular area.

A. "Onion-skin" pattern; one mantle zone may surround two or more germinal centers.

B. Obliterated.

C. Hypervascular.

135

Castleman's disease, plasma-cell type, histology:

A. Germinal centers.
B. Sinuses.
C. Interfollicular area.

A. Some are atrophic, some hyperplastic.

B. May be patent.

C. Hypervascular; sheets of plasma cells.

136

Castleman's disease, multicentric type, histology.

Similar to that of plasma-cell type, but occurring in many lymph nodes.

137

Castleman's disease, plasmablastic type.

Type of multicentric Castleman's disease in which plasmablast-like cells occupy germinal centers and the interfollicular area.

138

Castleman's disease: Monoclonality (3).

Plasma-cell type: Plasma cells may be restricted to IgG-lambda or IgA-lambda.

Plasmablastic type: Plasmablasts are restricted to IgM-lambda.

No clonality of rearrangement of IgH.

139

Castleman's disease: Immunohistochemistry (2).

Regressed follicles: CD21 and CD23.

Multicentric type (up to 40%): HHV8.

140

Castleman's disease: Laboratory abnormality.

Increased IL-6 in the serum.

141

Castleman's disease vs. B-cell lymphoma: Molecular test.

B-cell lymphoma: IgH is clonality rearranged.

142

Castleman's disease vs. HIV-associated lymphadenopathy (3).

HIV-associated lymphadenopathy:

- Attenuated mantle zones.
- No "onion-skin" pattern.
- No "lollipop" follicles.

143

Castleman's disease vs. angioimmunoblastic T-cell lymphoma.

AITCL: Atypical small to medium-sized lymphocytes with clear cytoplasm.

144

Castleman's disease vs. thymoma.

Thymoma: Epithelial cells (confirmable by IHC).

145

Castleman's disease vs. autoimmune lymphadenopathy.

Autoimmune lymphadenopathy can also show sheets of plasma cells.

Distinction requires clinical correlation.

146

Castleman's disease vs. plasma-cell neoplasm.

Plasma-cell neoplasm lacks the typical follicular changes of Castleman's disease.

147

SLL/CLL: Components of the proliferation centers (3).

Small lymphocytes.

Prolymphocytes.

Paraimmunoblasts.

148

SLL/CLL: Flow cytometry (2,2,1).

Positive: CD5, CD23.

Dim: CD20, sIg.

Negative: FMC7.

149

SLL/CLL: Chromosomal abnormalities (4).

del(13q14).

+12.

del(11q22).

del(17p13).

150

SLL/CLL: Progression to DLBCL.

Occurs in 5-10% of patients.

151

SLL/CLL: Expression of cyclin D1 (3).

Dim expression in the proliferation centers occurs rarely.

No t(11;14).

Should not cause a diagnosis of mantle-cell lymphoma.

152

Follicular lymphoma: Involvement of extranodal lymphoid organs.

Occurs in most patients.

153

Follicular lymphoma: Sites of primary extranodal disease (3).

Duodenum.

Breast.

Skin.

Other sites.

154

Follicular lymphoma:

A. Mantle zones.
B. Capsule.

A. Attenuated.

B. May be ruptured, with extranodal extension of the lymphoma.

155

Follicular lymphoma: Grading.

Grade 2 has 6-15 centroblasts per hpf.

Grades 1 and 2 are considered low grade.

Grade 3A: Centrocytes and centroblasts.

Grade 3B: Centroblasts only.

156

Follicular lymphoma: Diagnosis of diffuse area consisting mainly of centroblasts.

An additional diagnosis of DLBCL is made.

157

Follicular lymphoma: Expression of CD20 on flow cytometry.

Bright.

158

Follicular lymphoma: IHC (3).

Positive: CD10, Bcl-2, Bcl-6.

159

Follicular lymphoma: Immunochemical anomalies of high-grade tumors (2).

May lack CD10.

May lack Bcl-2.

May express Mum-1.

160

Follicular lymphoma: Use of immunohistochemistry in grading.

Ki-67 . . .

- Less than 20% of cells proliferate: Low grade.
- More than 20%: High grade.

161

Follicular lymphoma: Additional immunohistochemistry.

CD21 and CD23:

- Reveal effaced germinal centers in follicular lymphoma.
- Not so in DLBCL.

162

Follicular lymphoma: Rearrangements (2).

t(14;18) :: IGH-BCL2 in most cases.

Rearrangement of BCL6 in some cases, esp. of grade 3B.

163

Follicular lymphoma: Genotype of aberrant type.

Cases that lack t(14;18) and expression of Bcl-2 have postgerminal-center genes.

164

Follicular lymphoma vs. reactive follicular hyperplasia: Proliferation rate.

Reactive follicular hyperplasia: Greater than 90%.

165

Mantle-cell lymphoma: Frequency of extranodal disease at presentation.

Present in most patients.

166

Mantle-cell lymphoma:

A. Median survival.
B. Presentation that may correlate with a better prognosis.

A. Three to four years.

B. Absence of nodal disease.

167

Mantle-cell lymphoma: Non-malignant histologic features (2).

Hyalinized small vessels.

Scattered epithelioid histiocytes containing no nuclear débris.

168

Mantle-cell lymphoma: Variants (2).

Blastoid:
- Fine chromatin.
- Twenty to thirty mitotic figures per 10 hpf.

Pleomorphic: Large, pleomorphic cells with large nucleoli.

169

Mantle-cell lymphoma: Effect of proliferation of tumor cells on prognosis (2).

Each of these can worsen the prognosis:

- Mitotic rate greater than 10 per hpf.
- Proliferation rate of greater than 40% by Ki-67.

170

Mantle-cell lymphoma: Newer immunohistochemical marker.

SOX11.

171

Mantle-cell lymphoma: Translocation.

t(11;14) :: CCND1-IGH.

172

Mantle-cell lymphoma: Immunophenotypic aberrations (2).

Rare: Absence of CD5, expression of CD23 or CD10.

Very rare: Absence of cyclin D1 and t(11;14).

173

Mantle-cell lymphoma: How to recognize cases that lack expression of cyclin D1 and t(11;14).

They express SOX11.

174

Nodal marginal-zone lymphoma: Presentation.

Asymptomatic lymphadenopathy but with disease in advanced stage.

175

Nodal marginal-zone lymphoma: Architecture.

Cells surround reactive lymphoid follicles and often infiltrate them (follicular colonization).

176

Nodal marginal-zone lymphoma: Cellular components.

Monocytoid B cells.

Plasma cells.

Immunoblasts.

177

Nodal marginal-zone lymphoma: Immunophenotype (2,1,1).

Bright: CD20, sIg.

Usually positive: Bcl-2.

Variable (50%): CD43.

178

Nodal marginal-zone lymphoma: Cytogenetics (2).

A few cases may show +3, +7, or +18.

Translocations involving BCL10 and MALT1 are not observed.

179

Nodal marginal-zone lymphoma vs. reactive lymph node with hyperplasia of monocytoid B cells (3).

Reactive lymph node:

- No expression of Bcl-2.
- No clonality plasma cells.
- No rearrangement of IGH by PCR.

180

Nodal marginal-zone lymphoma vs. lymphoplasmacytic lymphoma (4).

LPL:

- Usually arises in the bone marrow.
- Increased IgM with hyperviscosity.
- Preservation of nodal architecture.
- Mutations in MYD88.

181

Lymphoplasmacytic lymphoma: Typical presentation.

Weakness and fatigue due to anemia.

182

Lymphoplasmacytic lymphoma: Neoplastic cellular components.

Small lymphocytes.

Plasma cells.

Plasmacytoid lymphocytes.

183

Lymphoplasmacytic lymphoma: Non-neoplastic cells that may be seen (3).

PAS-positive (immunoglobulin-laden) macrophages in open sinuses.

Hemosiderin-laden macrophages.

Mast cells.

184

Lymphoplasmacytic lymphoma: Mutation.

L265P in MYD88.

185

Lymphoplasmacytic lymphoma: Relation to increased IgM in the serum (2).

Some lymphoplasmacytic lymphomas secrete IgG or IgA instead of IgM.

Marginal-zone lymphomas and CLL can secrete IgM.

186

Diffuse large B-cell lymphoma: Frequency of disease in advanced stage at presentation.

About 60%.

187

Diffuse large B-cell lymphoma:

A. Frequency of extranodal disease at presentation.
B. Leading extranodal site.

A. About 40%.

B. The gastrointestinal tract.

188

Diffuse large B-cell lymphoma: Association with immunosuppression (3).

DLBCL is more common in patients with

- HIV.
- History of transplant.
- Primary immunodeficiency.

189

Diffuse large B-cell lymphoma: Infectious association.

EBV is present in most cases.

190

EBV-positive diffuse large B-cell lymphoma of the elderly.

Occurs in patients over 50 years of age

May be associated with senescence of the immune system.

191

Diffuse large B-cell lymphoma, centroblastic type: Cytology.

Nucleus: Round.

Nucleolus: Several, small.

Cytoplasm: Scant.

192

Diffuse large B-cell lymphoma, immunoblastic type: Cytology.

Nucleus: Round.

Nucleolus: Single, large, central.

Cytoplasm: Moderate, basophilic.

193

EBV-positive diffuse large B-cell lymphoma of the elderly: Histology (3).

Variably sized tumor cells.

Many admixed reactive cells.

Necrosis.

194

Diffuse large B-cell lymphoma: Expression of B-cell markers (5,4).

Positive: CD20, CD79a, Pax-5, Oct-2, Bob.1.

Variable: CD10, Bcl-2, Bcl-6, Mum-1.

195

Diffuse large B-cell lymphoma: Use in immunohistochemistry in classification.

The algorithms of Hans and Choi are not yet standardized for routine use.

196

Diffuse large B-cell lymphoma: Rate of proliferation by Ki-67.

Over 40%

197

Diffuse large B-cell lymphoma: Additional immunohistochemistry (2).

Some cases show

- Expression of CD30.
- Aberrant expression of CD5.

198

EBV-positive diffuse large B-cell lymphoma of the elderly: Immunohistochemistry (1,2).

Positive: Mum-1.

Negative: CD10, Bcl-6.

199

EBV-positive diffuse large B-cell lymphoma of the elderly: Additional ancillary test.

ISH for EBV.

200

Diffuse large B-cell lymphoma: Mutation associated with a poor prognosis.

Translocation involving c-MYC, especially when associated with

- Translocation of IGH with BCL2.
- Break in BCL6.

201

Classification of diffuse large B-cell lymphoma:

A. Basis.
B. Classes.

A. Gene-expression profiling by DNA microarrays.

B. Germinal-center type (better prognosis), activated-B-cell type.

202

Diffuse large B-cell lymphoma: Type that can mimic classical Hodgkin's lymphoma.

Anaplastic DLBCL.

203

"Gray-zone" lymphoma:

A. Definition.
B. Most common location.

A. Lymphoma that shares features with DLBCL and classical Hodgkin's lymphoma.

B. Mediastinum.

204

Diffuse large B-cell lymphoma: Relevance of immunophenotype to treatment.

CD30-positive DLBCL may respond to brentuximab vedotin.

205

Diffuse large B-cell lymphoma: Another type of "overlap" lymphoma.

One with features of DLBCL and Burkitt's lymphoma.

206

Lymphoblastic lymphoma: Types.

T-cell type: 90%, lymph nodes or mediastinum.

B-cell type: 10%, lymph nodes and extranodal sites.

207

Lymphoblastic lymphoma: Rate of progression to leukemia.

About 50%.

208

Lymphoblastic lymphoma: Prognosis.

Adults: T-LBL has better outcomes.

Children: T-LBL and B-LBL have similar outcomes.

209

Lymphoblastic lymphoma: Architecture of nodal infiltrate.

Usually diffuse; rarely paracortical.

210

Lymphoblastic lymphoma of T-cell lineage: Most commonly expressed markers (8).

TdT, CD2, CD3, CD5, CD7; CD1a, CD99, CD43.

211

Lymphoblastic lymphoma of T-cell lineage: Less commonly expressed markers (2).

CD10 in 40% of cases.

CD34 in 20% of cases.

212

Lymphoblastic lymphoma of T-cell lineage: Expression of CD4 and CD8.

Most cases are double positive.

A smaller proportion are double negative.

Rare cases express only one of these markers.

213

Lymphoblastic lymphoma of B-cell lineage: Immunophenotype (5,2).

Positive: TdT, CD34, CD10, Pax-5, CD79a.

Negative: CD20, light chains.

214

Lymphoblastic lymphoma: Aberrantly expressed antigens.

Some tumors express myeloid markers such as CD13, CD33, CD117.

215

Lymphoblastic lymphoma: PCR.

T-LBL: Rearrangement of TCR-gamma.

B-LBL: Monoclonal IGH.

Some tumors show both mutations.

216

Lymphoblastic lymphoma: Sanger sequencing.

About half of cases of T-LBL show activating mutations of the NOTCH1 gene.

217

Lymphoblastic lymphoma vs. Burkitt's lymphoma: Immunophenotype.

Burkitt's lymphoma . . .

- Positive: CD20 (bright).
- Negative: CD34, TdT.

218

Lymphoblastic lymphoma vs. T-cell-rich thymoma: Histology (

T-cell-rich thymoma:

- Fibrous bands impart lobular architecture.
- Immunohistochemistry demonstrates epithelial cells.

219

Lymphoblastic lymphoma vs. T-cell-rich thymoma: Flow cytometry.

T-cell-rich thymoma may show various populations of T lymphocytes.

220

Lymphocytic markers that may be expressed by myeloid sarcoma (6).

TdT.

CD4, CD7, CD43.

Pax-5, CD79a.

221

Indolent T-lymphoblastic proliferation: Definition (2).

Polyclonal proliferation of T lymphoblasts.

No change in nodal architecture.

222

Indolent T-lymphoblastic proliferation: Associations (3).

Castleman's disease.

Various hematologic malignancies.

Carcinomas.

223

Indolent T-lymphoblastic proliferation: Treatment.

None required.

224

Lymphoblastic leukemia: Recommended blast count.

More than 25%.

225

Burkitt's lymphoma: Clinical forms.

Endemic.

Sporadic.

Immunodeficiency-associated.

226

Burkitt's lymphoma, endemic:

A. Geography.
B. Median age of patient.
C. Sites.

A. Equatorial Africa.

B. Six years.

C. Abdominal cavity, jaw.

227

Burkitt's lymphoma, sporadic:

A. Median age (2).
B. Sites (2).
C. Lymphadenopathy.

A. Eleven years in children, 30 in adults.

B. Gastrointestinal tract, genitourinary organs.

C. Localized.

228

Burkitt's lymphoma, immunodeficiency-associated:

A. Typical patient.
B. Sites (3).
C. Effect of HAART.

A. One with HIV and a relatively high CD4 count and no opportunistic infections.

B. Lymph nodes, bone marrow, CNS.

C. No effect on incidence of Burkitt's lymphoma.

229

Burkitt's lymphoma: Prognosis.

Can be cured by means of extensive chemotherapy.

230

Burkitt's lymphoma: Immunophenotype (3,3).

Positive: B-cell antigens, CD10, Bcl-6.

Negative: Bcl-2, TdT, Mum1.

231

Burkitt's lymphoma: Relation to EBV.

ISH for EBV . . .

- Endemic: Positive in nearly all cases.
- Other types: Positive in many cases.

232

Burkitt's lymphoma: Cytogenetics.

Rearrangement of 8q24 involving MYC.

233

Burkitt's lymphoma: Clinical predictors of worse prognosis (3).

Older age.

Black race.

Advanced stage of disease.

234

B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt's lymphoma: Typical patient.

Older adult with generalized lymphadenopathy or with extranodal disease.

235

B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt's lymphoma: Behavior.

Very aggressive:

- Presents in advanced stage.
- Virtually no response to chemotherapy.
- Poor prognosis.

236

B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt's lymphoma: Histology (

Often show the starry-sky pattern.

In some tumors, cells are larger or more pleomorphic than those of Burkitt's lymphoma.

In some tumors, the cells resemble those of Burkitt's lymphoma but have a different karyotype.

237

B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt's lymphoma: Immunophenotype.

Cases that resemble DLBCL:
- Typical phenotype of Burkitt's lymphoma.
- Proliferation rate of more than 90%.

Cases that resemble Burkitt's lymphoma:
- Strong expression of Bcl-2, or
- Proliferation rate of less than 90%.

238

B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt's lymphoma: Mutations.

Cases that resemble DLBCL but have the immunophenotype of Burkitt's lymphoma: Simple rearrangement of MYC.

Cases that resemble Burkitt's lymphoma may have a complex karyotype or a rearrangement of MYC + rearrangement of BCL2 and/or BCL6.

239

B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt's lymphoma:

A. "Double-hit" type.
B. "Triple-hit" type.

A. Rearrangement of (MYC) and (BCL2 or BCL6).

B. Rearrangement of all 3 genes.

240

Examples of "double-hit" lymphomas with acquired mutations of MYC (4).

Diffuse large B-cell lymphoma.

Follicular lymphoma.

Lymphoblastic lymphoma.

Plasma-cell myeloma.

241

"Double-hit" lymphoma arising from follicular lymphoma: Possible histologic features (6).

Diffuse growth.

Absence of centrocytes.

Blastoid growth.

Starry-sky pattern.

Very high proliferation.

Focal necrosis.

242

Angioimmunoblastic T-cell lymphoma: Typical patient.

Elderly adult with organomegaly and "B" symptoms.

243

Angioimmunoblastic T-cell lymphoma: Less common signs and symptoms (4).

Rash.

Polyarthralgia.

Pleural effusion, ascites.

244

Angioimmunoblastic T-cell lymphoma: Prognosis.

Poor.

245

Angioimmunoblastic T-cell lymphoma: Architecture (4).

Partial effacement of lymph node.

Paracortical location of tumor cells.

Paracortical vascular proliferation (high-endothelial venules).

Expansion of FDC meshworks (demonstrable by IHC for CD21, CD23).

246

Angioimmunoblastic T-cell lymphoma: Cells (2).

Tumor cells: Atypical, small to medium-sized, moderate amount of clear cytoplasm.

Other cells: Reactive small lymphocytes, immunoblasts, eosinophils, plasma cells, histiocytes.

247

Angioimmunoblastic T-cell lymphoma: Expession of T-cell antigens.

Positive: CD4.

Most of the other expected T-cell antigens are expressed, but loss of one or more is not uncommon.

248

Angioimmunoblastic T-cell lymphoma: Additional markers (4).

Positive: CD10, Bcl-6, CXCL13, PD-1.

This is the immunophenotype of follicular T-helper cells.

249

Angioimmunoblastic T-cell lymphoma: Association with EBV.

EBV is present in scattered immunoblasts in most cases.

250

Angioimmunoblastic T-cell lymphoma: PCR (2).

Monoclonal rearrangement of TCR-gamma.

Ten percent of cases: Concurrent monoclonal rearrangement of IGH.

251

Angioimmunoblastic T-cell lymphoma: Cytogenetics.

+3, +5, +X.

252

Angioimmunoblastic T-cell lymphoma vs. peripheral T-cell lymphoma, NOS (4).

PTCL-NOS:

- Tumor cells in the germinal centers or the mantle zones.
- No enlarged FDC meshworks.
- No large high-endothelial vessels.
- Presentation is usually in an early stage.

253

Anaplastic large-cell lymphoma: Epidemiology (2).

ALK-positive: Second and third decades, mostly males.

ALK-negative: Middle-aged and elderly, no predilection for gender.

254

Anaplastic large-cell lymphoma: Typical presentation.

Lymphadenopathy, extranodal disease, systemic symptoms.

255

Anaplastic large-cell lymphoma: Prognosis.

Better in ALK-positive tumors.

256

Anaplastic large-cell lymphoma: Location of infiltrate.

The sinuses.

257

Anaplastic large-cell lymphoma: Cytology.

Tumor cells are large and have eccentric reniform nuclei.

"Hallmark" cells have doughnut-shaped or wreath-like nuclei.

258

Anaplastic large-cell lymphoma: Histologic variants (3).

Common: Pleomorphic large cells with "hallmark" nuclei.

Lymphohistiocytic: Many admixed histiocytes.

Small-cell: Most small- to medium-sized tumor cells.

259

Anaplastic large-cell lymphoma: Expressed antigens (8).

Always: CD30.

Usually: CD45, EMA, Bcl-6, clusterin; TIA1, granzyme B, perforin.

260

Anaplastic large-cell lymphoma: Usually unexpressed antigens (2).

CD3, Bcl-2.

261

Anaplastic large-cell lymphoma: Expression of T-cell markers.

CD2, CD5, and/or CD4 is usually expressed.

262

Anaplastic large-cell lymphoma: "Null-cell" type.

T-cell lineage is apparent only at the genetic level.

263

Anaplastic large-cell lymphoma: Pattern of staining for ALK.

May be nuclear, cytoplasmic, or membranous, depending on the translocation.

264

Anaplastic large-cell lymphoma: Aberrant expression of antigens.

Some tumors express myeloid antigens.

265

Anaplastic large-cell lymphoma: Association with EBV.

None.

266

Anaplastic large-cell lymphoma: Cytogenetics.

t(2;5)(p23;q35): 80% of tumors.

t(1;2).

inv(2).

267

Anaplastic large-cell lymphoma: Examples of DLBCL that can mimic it (2).

ALK-positive, EMA-positive DLBCL . . .
- Positive: CD138, cIg.
- Negative: CD30, T-cell antigens.

CD30-positive DLBCL that resembles ALCL morphologically:
- Positive: B-cell antigens.
- Negative: T-cell antigens.

268

Anaplastic large-cell lymphoma vs. peripheral T-cell lymphoma, NOS (2).

PTCL, NOS:

- Better retention of T-cell antigens.
- Usually no expression of EMA.

269

Anaplastic large-cell lymphoma: Treatment.

Anti-CD30 (brentuximab vedotin) may help.

270

Peripheral T-cell lymphoma, NOS: Typical patient.

Middle-aged or elderly male.

271

Peripheral T-cell lymphoma, NOS:

A. Typical presentation.
B. Prognosis.

A. Advanced disease.

B. Poor.

272

Peripheral T-cell lymphoma, NOS: Pattern of infiltrate.

Paracortical, follicular, or diffuse.

273

Peripheral T-cell lymphoma, NOS: Tumor cells (3).

Medium-sized or large, pleomorphic, and monotonous.

Cells form sheets.

Clear cells or Reed-Sternberg cells may be visible.

274

Peripheral T-cell lymphoma, NOS: Other cells (4).

Small lymphocytes, plasma cells, eosinophils, histiocytes.

275

Peripheral T-cell lymphoma, NOS: Additional possible histologic feature.

Large high-endothelial venules.

276

Peripheral T-cell lymphoma, NOS: Histologic variants (3).

Lymphoepithelioid (Lennert's lymphoma): Small tumor cells are obscured by epithelioid histiocytes.

Follicular: Atypical clear cells in germinal centers or in mantle zones.

T-zone: Perifollicular growth with minimal cytologic atypia.

277

Peripheral T-cell lymphoma, NOS: Expression of T-cell antigens (3).

Frequent loss of CD5 and CD7.

CD4 is usually expressed.

CD8 is more often expressed in Lennert's lymphoma.

278

Peripheral T-cell lymphoma, NOS: Expression of CD30.

Absent, weak, or focal.

279

Peripheral T-cell lymphoma, NOS: Rate of proliferation.

High.

280

Peripheral T-cell lymphoma, NOS: Association with EBV.

Present in the Reed-Sternberg-like cells.

281

Peripheral T-cell lymphoma, NOS: Additional immunohistochemistry.

Some tumors (esp. the follicular variant) express markers of follicular T-helper cells:
- CD10.
- Bcl-6.
- PD-1.
- CXCL13.

282

Peripheral T-cell lymphoma, NOS, T-zone variant: Differential diagnosis.

Reactive paracortical hyperplasia:

- No loss of T-cell antigens.
- Normal ratio of CD4-positive to CD8-positive lymphocytes.

283

Peripheral T-cell lymphoma, NOS vs. angioimmunoblastic T-cell lymphoma.

AITCL: Expanded FDC networks.

284

Nodular lymphocyte-predominant Hodgkin's lymphoma: Proportion of all Hodgkin's lymphomas.

5%.

285

Nodular lymphocyte-predominant Hodgkin's lymphoma: Epidemiology.

Young patients.

Strong male predominance.

286

Nodular lymphocyte-predominant Hodgkin's lymphoma: Typical presentation.

Localized lymphadenopathy.

287

Nodular lymphocyte-predominant Hodgkin's lymphoma: Names of large tumor cell.

Lymphocyte-predominant.

Lymphocytic and histiocytic.

Popcorn.

288

Nodular lymphocyte-predominant Hodgkin's lymphoma: What should not be seen (4).

Neutrophils.

Eosinophils.

Fibrosis.

Necrosis.

289

Nodular lymphocyte-predominant Hodgkin's lymphoma: Antigens expressed by tumor cells (8).

CD45.

CD20, CD79a, Pax-5.

Bcl-6, EMA.

Both Oct-2 and Bob.1 are expressed.

290

Nodular lymphocyte-predominant Hodgkin's lymphoma: Antigens not expressed by tumor cells (4).

CD30, CD15, EBV, fascin.

291

Nodular lymphocyte-predominant Hodgkin's lymphoma: Antigens expressed by the T lymphocytes in the nodules (4).

CD3, CD4, CD57, PD-1.

292

Nodular lymphocyte-predominant Hodgkin's lymphoma: Additional immunohistochemistry (2).

CD21 and CD23 highlight the expanded FDC meshworks.

293

Nodular lymphocyte-predominant Hodgkin's lymphoma:

A. Flow cytometry.
B. PCR.

A. May reveal CD4/CD8 double-positive T cells.

B. Does not detect clonal rearrangement of IGH.

294

Nodular lymphocyte-predominant Hodgkin's lymphoma vs. T-cell/histiocyte-rich DLBCL

T-cell/histiocyte-rich DLBCL:

- Diffuse, not nodular; complete effacement of architecture.
- CD21 and CD23 reveal no expansion of FDC meshworks.
- No rosettes of PD-1-positive T cells.

295

Nodular lymphocyte-predominant Hodgkin's lymphoma: Prognosis (3).

Cured if excised early.

Otherwise:
- Relapses and recurrences are frequent.
- Patients are predisposed to develop DLBCL.

296

Nodular-sclerosis Hodgkin's lymphoma: Most common sites.

Cervical lymph nodes.

Mediastinum (involved in 80% of cases).

297

Nodular-sclerosis Hodgkin's lymphoma: Variants of Reed-Sternberg cells (4).

Hodgkin's cells: Mononuclear.

Wreath cells: Multinucleate.

Mummified cells: Condensed cytoplasm, pyknotic nuclei.

Lacunar cells: Due to formalin-induced retraction of cytoplasm.

298

Nodular-sclerosis Hodgkin's lymphoma: Non-neoplastic cells (5).

Small lymphocytes.

Histiocytes.

Eosinophils.

Plasma cells.

Neutrophils occasionally.

299

Nodular-sclerosis Hodgkin's lymphoma: Additional histologic features (2).

Broad bands of sclerosis.

Necrosis and granulomas in some cases.

301

Nodular-sclerosis Hodgkin's lymphoma: Immunohistochemistry (4,2).

Positive: CD30, CD15, Pax-5, Mum-1.

Negative: CD45, EMA.

302

Nodular-sclerosis Hodgkin's lymphoma: Expression of CD20.

Usually negative but may be weak in some of the tumor cells in some cases.

303

Nodular-sclerosis Hodgkin's lymphoma: Expression of Oct-2 and Bob.1.

One or the other is positive, but not both.

304

Nodular-sclerosis Hodgkin's lymphoma: Expression of EBV.

Detectable by EBER in 10-40% of cases.

305

Nodular-sclerosis Hodgkin's lymphoma vs. HL of mixed-cellularity type.

Mixed-cellularity type:

- Inconspicuous or absent fibrous bands.
- Much stronger association with EBV.

306

Nodular-sclerosis Hodgkin's lymphoma vs. PTCL, NOS with true Reed-Sternberg cells.

In the latter, the T cells are morphologically (usually) and immunophenotypically aberrant.

307

Nodular-sclerosis Hodgkin's lymphoma vs. reactive immunoblasts.

Reactive immunoblasts express CD30 but not CD15.

308

Nodular-sclerosis Hodgkin's lymphoma: Best place to look for Reed-Sternberg cells.

Around the necrotic areas.

309

Mixed-cellularity Hodgkin's lymphoma:

A. Associations (3).
B. Median age at presentation.

A. Male sex, HIV, residence in developing country.

B. 38 years (older than that of NS-CHL).

310

Mixed-cellularity Hodgkin's lymphoma:

A. Most common site.
B. Prognosis.

A. Cervical lymph nodes; rarely involves mediastinum.

B. Excellent.

311

Mixed-cellularity Hodgkin's lymphoma: Immunohistochemistry.

Same as that of NS-CHL.

312

Lymphocyte-rich Hodgkin's lymphoma:

A. Median age.
B. Gender predilection.

A. Older than that of other subtypes of CHL.

B. Mainly affects males.

313

Lymphocyte-rich Hodgkin's lymphoma:

A. Typical site.
B. Prognosis.

A. Cervical lymph nodes; rarely involves mediastinum.

B. Excellent.

314

Lymphocyte-rich Hodgkin's lymphoma: Histology (4).

Small lymphocytes form nodules that contain

- Small regressed germinal centers.
- Scattered Reed-Sternberg cells.
- Few or no granulocytes.

315

Lymphocyte-rich Hodgkin's lymphoma: Immunohistochemistry of tumor cells.

Same as that of NS-CHL.

316

Lymphocyte-rich Hodgkin's lymphoma: Other immunohistochemistry (2).

Small lymphocytes are mantle cells that express IgD.

Small regressed germinal centers express CD21 and CD23.

317

Lymphocyte-rich Hodgkin's lymphoma: Association with EBV.

Detectable by EBER in about half of cases.

318

Langerhans'-cell histiocytosis: Age group of peak incidence.

One to three years.

319

Langerhans'-cell histiocytosis: Pattern of infiltration.

Sinusoidal.

320

Langerhans'-cell histiocytosis: Cellular components.

Langerhans' cells.

Eosinophils, neutrophils, small lymphocytes.

321

Langerhans'-cell histiocytosis: Cytology of tumor cells.

Nuclei: Irregular; nuclear groove sometimes; inconspicuous nucleolus.

Cytoplasm: Ill-defined, acidophilic.

322

Langerhans'-cell histiocytosis: Immunohistochemistry (3).

S100: All Langerhans' cells.

CD1a, langerin: Some Langerhans' cells..

323

Langerhans'-cell histiocytosis: Mutation.

V600E in BRAF in about half of cases.

324

Langerhans'-cell histiocytosis vs. Rosai-Dorfman disease (3).

Rosai-Dorfman disease:

- Large nucleoli.
- Emperipolesis.
- Absence of CD1a and langerin (but S100 is expressed).

325

Langerhans'-cell histiocytosis vs. dermatopathic lymphadenopathy (2).

Dermatopathic lymphadenopathy:

- Paracortical, not sinusoidal, infiltrate.
- Langerhans' cells are not accompanied by granulocytes or plasma cells.

326

Langerhans' cells:

A. Functions (2).
B. Origin.

A. Antigen presentation, phagocytosis.

B. The skin.

327

Mixed-cellularity Hodgkin's lymphoma: Histology.

Similar to that of NS-CHL, but without broad bands of collagen.

328

Kaposi's sarcoma: Locations in the lymph node (4).

Early:

- Capsule.
- Hilum.
- Fat around the node.

Late: Entire node may be replaced.

329

Kaposi's sarcoma: Immunohistochemistry (5).

Positive: CD34, CD31, ERG, FVIII-related antigen, LANA (HHV8).

330

Vascular transformation of lymph nodes: Histology

Congestion of all subcapsular and medullary sinuses.

Anastomosing network of small vascular channels lined by reactive endothelial cells.

331

Kaposi's sarcoma vs. vascular transformation of lymph node (2).

Vascular transformation of lymph node:

- Sparing of capsule.
- No hyaline globules.

332

Extramedullary hematopoiesis: Locations in the lymph node (2).

Paracortex.

Sinuses.

333

Extramedullary hematopoiesis: Immunohistochemical markers of megakaryocytes (2).

CD42b, CD61.

334

Myeloid sarcoma: Clinical settings (4).

Established diagnosis of AML.

Harbinger of AML.

Sign of impending blast crisis in CML.

Sign of leukemic transformation of MDS.

335

Extramedullary hematopoiesis: Sites (4).

Soft tissues.

Lymph nodes.

Skin.

Bones (lytic lesions).

336

Extramedullary hematopoiesis: Histology.

Sheets of myeloblasts with or without maturation.

337

Myeloid sarcoma: Aberrantly expressed antigens.

CD43, CD4, or CD7 may be expressed.

338

Myeloid sarcoma: Clue to diagnosis.

High-grade neoplasm in the lymph node that does not express CD3, CD20, CD138, or cytokeratin.

339

Mast-cell disease: Location in the lymph node.

May involve any compartment, but especially the paracortex.

340

Mast-cell disease: Histology (3).

Sheets or small clusters of mast cells.

Fibrosis.

Eosinophils (sometime enough to obscure the infiltrate).

341

Mast-cell disease: Aberrantly expressed markers (3).

CD2, CD25, CD30.

342

Mast-cell disease: Mutation.

Activating point mutation in codon 816 of KIT.

343

Mast-cell disease: Appearance in lymph node on routine stain.

Because their granules are inconspicuous without special stains, mast cells may be confused with

- Fibrotic foci.
- Histiocytes.
- Lymphoid follicles.