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Lymphoma - Non B cell neoplasms

T/NK cell disorders

T cell prolymphocytic leukemia


Reviewer: Dragos Luca, M.D. (see Reviewers page)
Revised: 31 October 2011, last major update August 2011
Copyright: (c) 2001-2011, PathologyOutlines.com, Inc.

Definition
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● T cell prolymphocytic leukemia (T-PLL) is an aggressive T cell leukemia, characterized by the proliferation of small to medium-sized prolymphocytes with a mature post-thymic T cell phenotype, involving the peripheral blood, bone marrow, lymph nodes, liver, spleen and skin (WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 4th Edition, Lyon 2008)

Terminology
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● Historically, small cell variants were termed T cell chronic lymphocytic leukemia

Epidemiology
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● Rare, 2% of mature lymphocytic leukemias in adults >30 years of age
● Median age 65 years; range: 30-94 years

Sites
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● Peripheral blood, bone marrow, lymph nodes, spleen, liver, skin

Clinical features
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● Presents with high WBC count (75% are >100K) and cutaneous (20-27%) or mucosal disease
● Lymphadenopathy (53%), hepatomegaly (40%), splenomegaly (73%), CNS involvement, anemia and thrombocytopenia, serous effusions (mostly pleural) (Am J Clin Pathol 2005;123:456)
● Normal serum Ig, HTLV-I negative

Case reports
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● 87 year old man with small cell variant with t(3;22) (Arch Pathol Lab Med 2005;129:1164)
● 48 year old man with CD4 to CD8 spontaneous immunophenotypical switch (Ann Hematol 2011;90:479)
● 45 year old woman with coexisting breast cancer (Cases J 2010 Jan 4;3:4)
● 82 year old man with small cell variant evolving to generalized leukemia cutis (Acta Derm Venereol 2009;89:509)

Treatment and prognosis
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● May initially be indolent, but median survival is usually less than 1 year
● Usually not curable, but cases with a more chronic course have been reported (may show an accelerated course after 2-3 years)
● Best treatment response with alemtuzumab (anti-CD52)
● Poor prognostic factors: high expression of TCL1 and AKT1

Postulated normal counterpart
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● Unknown T cell with a mature (post-thymic) immunophenotype (possibly intermediate between cortical and mature T lymphocytes weak surface CD3, strong CD7, double CD4/CD8 positive)

Micro description
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Peripheral blood and bone marrow:
● Small to medium sized lymphocytes with abundant basophilic, nongranular cytoplasm, atypical nucleus, prominent nucleolus
● Small cell variant: small cells with indistinct nucleoli; 19-25% of cases
● Cerebriform nuclei in 5% of cases
● All variants: cytoplasmic protrusions or blebs
● Diffuse BM infiltration

Other tissues:
● Diffuse involvement of splenic red and white pulp (atrophied) with invasion of blood vessels and splenic capsule
● Diffuse paracortical involvement of lymph nodes, sometimes with sparing of the follicles; increased and often infiltrated high endothelial venules
● Skin involvement is usually perivascular or periadnexal, may be diffuse dermal, no epidermotropism

Micro images
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Various images and review


Small cell variant: scant cytoplasm, condensed chromatin; shows TCR beta gene rearrangement


Peripheral blood (A&B)


Peripheral blood

Cytochemistry
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● Strong staining with α-naphthyl acetate esterase and acid phosphatase (dot-like in the Golgi region)

Positive stains
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● CD2, CD3, CD5, CD7, CD4 (60%), CD52 (high density expression, potential therapeutical target), TCL1
● CD4+/CD8- in 60% of cases, CD4+/CD8+ in 25%, CD4-/CD8+ in 15%

Negative stains
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● TdT, CD1a

Genetics and molecular
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● T cell receptor gene rearrangements (TRB@ & TRG@)
● 75-80% show inv 14(q11;q32) (affects T cell receptor) or other chromosome 14 translocations
● Reciprocal tandem translocations of TCL1 gene at 14q32.1 [t(14;14)(q11;q32)] in 10% of cases
● MTCP-1 gene at Xq28 in t(X;14)(q28;q11) translocations less common
● Chromosome 8 abnormalities in 70-80% of cases [idic 8p11, t(8;8)(p11-12;q12), trisomy 8q]
● ATM gene at 11q23, 12p13-, chromosome 6 abnormalities (33%), and 17 (26%), TP53 deletions

Additional references
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● Review articles: Am J Clin Pathol 2007;127:496, Cancer 2005;104:1808

End of Lymphoma - Non B cell neoplasms > T/NK cell disorders > T cell prolymphocytic leukemia


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