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Case 32 - Discussion

Hematopathology Case

 

 

CD3

CD5

CD7

CD10

CD20

BCL6

CD21

CD21

CD30

EBER-ISH

   

FLOW CYTOMETRY:

An abnormal T-cell population is detected by flow cytometry, expressing CD3 and CD4 with co-expression of CD10 and partial loss expression of CD7.

 

TCR GENE REARRANGEMENT ASSAY:

Positive for TRG@ gene rearrangement.

 

DIAGNOSIS:
Angioimmunoblastic T-cell lymphoma

   

Angioimmunoblastic T-cell lymphoma

CLINICAL FEATURES

  • A peripheral T-cell lymphoma with a polymorphous infiltrate in lymph node, a prominent proliferation of high endothelial venules and follicular dendritic cells;

  • Age: middle to elderly; Gender: M=F;

  • 15-20% of peripheral T-cell lymphoma, 1-2% of non-Hodgkin lymphoma;

  • Clinical presentations: often generalized peripheral lymphadenopathy, hepatosplenomegaly, frequent skin rash, and commonly bone marrow involvement upon biopsy.

MICROSCOPIC FINDINGS

  • Loss of normal lymph node architecture
    • Diffuse paracortical infiltrate of polymorphous neoplastic T cells
    • Lymph node architecture is partially or totally effaced
    • Lymphoid follicles, hyperplastic, depleted or regressed, with irregular borders and lack of mantle zones
  • Neoplastic T cells
    • Small to medium-sized but occasionally large cells, usually show minimal cytologic atypia
    • Abundant clear to pale cytoplasm, distinct cell membranes and irregular nuclear contour
    • Often in clusters around high endothelial venules
    • Often obscured by reactive lymphocytes, immunoblasts, plasma cells, histiocytes, and eosinophils
  • Prominent proliferation high endothelial venules
    • Prominent arborizing high endothelial venules with PAS positive amorphous perivascular material
    • The nuclei of endothelial cells are round to oval with regular nuclear contour and a small central nucleolus
  • Prominent proliferation of follicular dendritic cells
    • Follicular dendritic cell proliferation outside germinal centers/around high endothelial venules
    • Highlighted by CD21 staining
  • B cell proliferation
    • >70% are EBV positive
    • May be polymorphic or monomorphic, immunoblastic or plasmacytic
    • Immunoglobulin gene rearrangement detected in ~10% cases
    • May produce a Hodgkin-like proliferation with Reed-Sternberg-like cells
    • May develop into B-cell lymphoma in a small subset of cases

DIFFERENTIAL DIAGNOSES

  • Reactive lymphadenopathies

  • Multicentric Castleman's disease

  • Diffuse large B-cell lymphoma

  • Classical Hodgkin's Disease

IMMUNOHISTOCHEMISTRY AND SPECIAL STAINS

  • Neoplastic cells are mature T-cells with CD3+, CD4+, PD1, and CXCL13

  • In most cases, the neoplastic T-cells show aberrant expression of CD10 and BCL6

  • Loss of T-cell antigen such as CD7 can occur in some cases

  • EBV positive in >75% cases, mostly in B-cells, not T-cells

  • Follicular dendritic cells CD21+

CYTOGENETICS
  • TRG@ gene rearrangement in 75% cases
  • 90% have cytogenetic alterations: trisomy 3, trisomy 5 and gain of chromosome X

TREATMENT AND PROGNOSIS

  • Aggressive, median survival <3 years

REFERENCES

  • Jaffe ES, Harris NL, Stein H, Vardiman JW, editors. Pathology and genetics of tumours of haematopoietic and lymphoid tissues. World Health Organization classification of tumours. Lyon (France): IARC Press; 2001.

  • Practical Diagnosis of Hematologic Disorders, Fourth Edition. By Carl R. Kjeldsberg, 2006.