'''T-cell prolymphocytic leukemia (T-PLL)''' is a mature [T-cell] [leukemia] with aggressive behavior and predilection for [blood], [bone marrow], [lymph nodes], [liver], [spleen], and [skin] involvement.

Epidemiology

T-PLL is a rare leukemia, primarily affecting adults over the age of 30. It represents 2% of all small lymphocytic leukemias in adults.mat1

<ref name="mat1"> http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=1742486&query_hl=2&itool=pubmed_ExternalLink E Matutes, V Brito-Babapulle, J Swansbury, J Ellis, R Morilla, C Dearden, A Sempere, and D Catovsky. "Clinical and laboratory features of 78 cases of T-prolymphocytic leukemia.",''' Blood''', Dec 1991; 78: 3269 - 3274. '''PMID''': 1742486</ref>

Clinical Features

Clinical Presentation

Patients typically have systemic disease at presentation, including [hepatosplenomegaly], generalized [lymphadenopathy], and skin infiltrates.<ref name="who1"/>

Laboratory Findings

A high lymphocyte count (> 100 x 10⁹/L)along with [anemia] and [thrombocytopenia] are common findings. [HTLV-1] serologies are negative, and serum [immunoglobins] are within normal limits with no [paraproteins] present.<ref name="who1"/>

Sites of Involvement

Due to the systemic nature of this disease, leukemic cells can be found in peripheral blood, [lymph nodes], [bone marrow], [spleen], [liver], [skin].<ref name="who1">http://www.iarc.fr/WHO-BlueBooks/BBwebsite/bb3.html Jaffe E.S., Harris N.L., Stein H., Vardiman J.W. (eds): '''World Health Organization Classification of Tumors. Pathology and Genetics of Tumours of Haemopoietic and Lymphoid Tissues.''' IARC Press: Lyon 2001 </ref>

Morphology

Peripheral blood and bone marrow

In the peripheral blood, T-PLL consists of medium-sized [lymphocytes] with single [nucleoli] and [basophilic] [cytoplasm] with occasional blebs or projections. The [nuclei] are usually round to oval in shape, with occasional patients having cells with a more irregular nuclear outline that is similar to the cerebriform nuclear shape seen in [Sézary syndrome].<ref name="mat2">http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=3489482&query_hl=5&itool=pubmed_ExternalLink Matutes E, Garcia Talavera J, O'Brien M, Catovsky D. "The morphological spectrum of T-prolymphocytic leukaemia.", '''Br J Haematol.''' 1986 Sep;64(1):111-24. '''PMID''': 3489482</ref> Marrow involvement is typically diffuse with morphology similar to what is observed in peripheral blood.<ref name="who1"/>

Other sites

In the [spleen], the leukemic cell infiltrate both the [red pulp] and [white pulp], and [lymph node] involvement is typically diffuse through the [paracortex].<ref name="who1"/>. Skin infiltrates are seen in 20% of patients, and the infiltrates are usually dense and confined to the [dermis] and around the skin appendages.<ref name="mat1"/>

Variant morphology

A small cell variant comprises 20% of all T-PLL cases, and the Sézary cell-like (cerebriform) variant is seen in 5% of cases.<ref name="mat2"/>

Immunophenotype

T-PLL has the [immunophenotype] of a mature (post-thymic) T-lymphocyte, and the [neoplastic] cells are typically positive for pan-T antigens [CD2], [CD3], and [CD7] and negative for [TdT] and [CD1a]. The immunophenotype [CD4]/[CD8]- is present in 60% of cases, the CD4/CD8+ immunophenotype is present in 25%, and the CD4-/CD8+ immunophenotype is present in 15% of cases.<ref name="mat1"/>

Genetic Findings

Clonal TCR gene rearrangements for the ? and d chains are typically found. The most frequent chromosomal abnormality is the inversion of chromosome 14, specifcally inv 14(q11;q32). This is found in 80% of cases, while 10% of cases show a reciprocal translocation of [chromosome 14] (t(14;14)(q11;q32)). <ref name="bri1">http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=1913594&query_hl=8&itool=pubmed_ExternalLink
Brito-Babapulle V and Catovsky D. "Inversions and tandem translocations involving chromosome 14q11 and 14q32 in T-prolymphocytic leukemia and T-cell leukemias in patients with ataxia telangiectasia." '''Cancer Genet Cytogenet.''' 1991 Aug;55(1):1-9. '''PMID''': 1913594</ref><ref name="mal1"> http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=9614908&query_hl=13&itool=pubmed_ExternalLink Maljaei SH, Brito-Babapulle V, Hiorns LR, Catovsky D. "Abnormalities of chromosomes 8, 11, 14, and X in T-prolymphocytic leukemia studied by fluorescence in situ hybridization." '''Cancer Genet Cytogenet.''' 1998 Jun;103(2):110-6. '''PMID''': 9614908</ref> Also, abnormalities of [chromosome 8] are seen approximately 75% of patients, including idic (8p11), t(8;8)(p11-12;q12), and [trisomy] 8.<ref name="sor1">http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=11063795&query_hl=15&itool=pubmed_ExternalLink
Sorour A, Brito-Babapulle V, Smedley D, Yuille M, Catovsky D. "Unusual breakpoint distribution of 8p abnormalities in T-prolymphocytic leukemia: a study with YACS mapping to 8p11-p12."
'''Cancer Genet Cytogenet.''' 2000 Sep;121(2):128-32. '''PMID''': 11063795</ref>

Cell of origin

It is postulated that the originating cell line for this disease is a mature (post-thymic) T-cell.<ref name="who1"/>

References

E Matutes, V Brito-Babapulle, J Swansbury, J Ellis, R Morilla, C Dearden, A Sempere, and D Catovsky. "Clinical and laboratory features of 78 cases of T-prolymphocytic leukemia.",''' Blood''', Dec 1991; 78: 3269 - 3274. '''PMID''': 1742486