T cell prolymphocytic leukemia (T-PLL)
Epidemiology:
Common Sites:
- blood
- bone marrow
- lymph nodes
- liver
- spleen
- skin
Gross features:
- hepatosplenomegaly (most)
- generalized lymphadenopathy
- pleural effusions (minority)
Histologic features:
- small to medium-sized prolymphocytes:
- skin:
- dense dermal infiltrate
- often around appendages
- no epidermotropism
- spleen:
- dense red and white pulp infiltration
- blood film:
- small to medium lymphoid cells
- non-granular basophilic cytoplasm
- cytoplasmic protrusions or blebs
- round, oval, or markedly irregular nuclei
(Sezary cell-like variant)
- visible nucleolus (not in small cell variant)
- lymph nodes:
- diffuse involvement predominantly in
paracortex, may spare follicles
- prominent high endothelial venules
- small cell variant:
- cerebriform
cell variant:
Immunophenotype (mature, post-thymic
immunophenotype):
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Marker:
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Sensitivity:
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Specificity:
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Pan T-cell
antigens
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Alpha-naphthyl acetate esterase (dot-like staining in Golgi)
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CD2
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CD3 (may be
weak in membrane)
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CD7
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CD4
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60%
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CD8
(coexpressed with CD4)
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25%
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Almost unique
to T-PLL
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Molecular features:
- extraordinary conservation of both primary and
secondary genetic changes
- clonal rearrangement of TCR gamma and beta
chains (TRB@ and TRG@)
- inversion of chromosome 14 (80%)
- breakpoints in long arm at q11 and q32
- reciprocal tandem translocation
t(14;14)(q11;q32) (10%)
- juxtapose TCR alpha/beta locus (TRA@) with the
oncogenes TCL1 and TCL1b at 14q32.1
- chromosome 8 abnormalities (70-80%)
- idic (8p11)
- t(8;8)(p11-12;q12)
- trisomy 8q
- deletions of 12p13
- t(X;14)(q28;q11) (less common)
- TCR alpha/beta with MTCP1 gene (homologous to
TCL1) at Xq28
- Deletions at 11q23
- ataxia telangiectasia mutated (ATM gene)
- chromosome
6 abnormalities (33%)
- chromosome
17 abnormalities (26%)
Other features:
- aggressive, progressive course usually
- mean survival < 1y
- alemtuzumab (anti-CD52) shows best responses
- CBC:
- Lymphocytosis (usually over 100 x 10e9/L)
- anemia
- thrombocytopenia
- no M component in the serum
- HTLV serology negative (always)
References: