T- cell lymphoproliferative disorders Flashcards

1
Q

What immunophenotype do cortical T thymocytes have?

A
  • cytoCD3+, CD5+, CD7+, CD4+, CD8+, TdT+, CD1a+
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2
Q

What immunophenotypic features are associated with gamma delta T cell lymphoma?

A
  • Lack of expression of CD4, CD8 and CD5
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3
Q

What immunophenotypic features are associated with the follicular helper T cell subset?

A
  • CD4+, CD10+, BCL-6+, CD57+ , CXCR5+, PD-1+

- Secrete CXCL13 (receptor= CXCR5), IL4 and IL21

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4
Q

What T cell disorders can be CD4+ and CD8+

A
  • Cortical thymocyte T-ALL

- T-PLL

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5
Q

What T cell disorders can be CD4- and CD8-

A
  • Hepatosplenic T cell lymphoma
  • EATL
  • Some anaplastic T cell lymphomas
  • (NK lymphoma/ leukaemia)
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6
Q

Expression of what two genes has been proposed as being important in the delineation of different subtypes of peripheral T cell lymphoma NOS

A

1) GATA3 (Th2 cells, worse prognosis, more monotonous/ sheet-like)
2) TBX21/ T-BET (Th1, better prognosis, more heterogenous with an inflammatory background)

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7
Q

What is the “null-cell phenotype” in anaplastic T cell lymphoma and how can it be distinguished from HL?

A
  • Refers to the loss of the pan T cell antigens
  • Can be difficult to distinguish from HL as both are CD30+
  • In anaplastic T cell lymphoma: CD15 usually -ve, PAX5-, EBV-. May be ALK+. Granzyme and TIA positive.
  • In Hodgkin’s: LMP1 positive
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8
Q

What are the four histological subtypes of anaplastic T cell lymphoma?

A

1) Common pattern
2) Lymphohistiocytic
3) Small cell pattern
4) Hodgkin-like

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9
Q

What are the four subtypes of anaplastic T cell lymphoma

A

1) ALK+ (good prognosis)
2) DUSP22+ (good prognosis)
3) TP63+ (bad prognosis)
4) Triple negative (prognosis in between DUSP22 and TP63+)

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10
Q

What are the morphological features of angioimmunoblastic T cell lymphoma?

A
  • Polymorphous infiltrate with atypical T cells, plasma cells, histiocytes, eosinophils.
  • T cells have T helper follicular phenotype with 2 or more of: CD10, CXCR5, CXCL13, ICOS, PD1
  • Expanded FDC network
  • Large B cells in the background that are CD20 and EBV +
  • Arborising venules.
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11
Q

What mutations/ gene fusions are seen in angioimmunoblastic T cell lymphoma?

A
  • Mutations in TET2, DNMT3A, IDH2, RHOA, CD28

- Gene fusions in ITK-SYK, CTLA4- CD28

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12
Q

What is the immunophenotype of T-LGL?

A

CD3+, CD8+, C16+, CD57+
Diminished expression of CD5 and/or CD7
TIA, granzyme B positive

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13
Q

What genetic aberrations are typically seen in T-PLL?

A
  • Overexpression of TCL1, caused by genetic rearrangements that bring the TCL1 gene under the control of the TRA
    • inv(14) in 80%, t(14;14) in 10%
  • MTCP1 (a homologue of TCL1) is located on the X chromosme
    • t(X;14) in <10%

TCL1 and MTCP1 alterations enhance cell proliferation and survival through activation of a tyrosine kinase.

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14
Q

What is the definition of blood involvement in sezary syndrome?

A
  • Presence of an absolute Sézary cell count of greater than 1000/µL,
  • CD4:CD8 ratio greater than or equal to 10 due to CD4 cell expansion
  • Loss of one or more T-cell antigens (>30% of T-cells with CD4+/CD7– phenotype or >40% of T cells with a CD4+/CD26–phenotype)
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15
Q

What are the immunophenotypic features of sezary cells?

A
  • CD3+, CD5+ and CD4+, typically without expression of CD7 or CD26.
  • PD1+
  • Loss of CD2 in ~25% of cases.
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