T-cell Prolymphocytic Leukemia.

BACKGROUND: T-cell prolymphocytic leukemia (T-PLL) is a post-thymic T-cell malignancy with aggressive clinical course. Although T-PLL has been referred to under different designations, it is a distinct clinico-biological entity and should be distinguished from other T-cell disorders. METHODS: The literature on T-PLL is reviewed. Experience on the clinical and laboratory features, differential diagnosis, and therapy on a large series of T-PLL patients is presented. RESULTS: T-PLL affects adults and occurs more frequently in men. The principal disease characteristics are organomegaly, skin lesions, and a raised lymphocyte count. Immunological markers show a post-thymic T-cell phenotype (TdT- CD2+ CD5+ CD3ñ) with strong expression of CD7. A CD4+ CD8- phenotype is seen in two thirds of cases. CD4 and CD8 are coexpressed in 25%, and a CD4- CD8+ phenotype is rare. Cytogenetics show a recurrent abnormality inv(14)(q11;q32) that is always associated to other aberrations (particularly iso8q or trisomy 8). Differential diagnosis between T-PLL and other T-cell malignancies is based on a constellation of clinical and laboratory features. Generally, T-PLL patients are refractory to the therapy used in lymphoid disorders. Median survival is short but is improving with the use of 2'-deoxycoformycin and the humanized monoclonal antibody, anti-CDw52 (Campath-1H). CONCLUSIONS: T-PLL is a distinct T-cell disorder with characteristic clinical and laboratory features and a poor prognosis. A precise diagnosis of this disease is important in determining patient management and treatment.