T-Cell Prolymphocytic Leukemia

T-cell prolymphocytic leukemia (T-PLL) is a rare mature (postthymic) T-cell lymphoproliferative disorder that affects adults with a median age of 64 years, occurs more frequently in men, and is characterized by an aggressive clinical course and poor outcome [1–4]. The WHO classification defines T-PLL as an aggressive T-cell leukemia of proliferating small- to medium-sized T-lymphocytic cells with prominent nucleoli that despite their postthymic origin and mature phenotype are called T-prolymphocytes [1,2,4–7]. The principal disease characteristics are B-symptoms, organomegaly (especially splenomegaly and lymphadenopathy), anemia, thrombocytopeni,a and prominent (often rapidly increasing) lymphocytosis in the blood (>100 × 10⁹/L) with involvement of bone marrow (BM). Nodal and extranodal presentation is also frequent, including involvement of the skin, liver, pleural or peritoneal cavities, and central nervous system (CNS) [1,8]. Skin manifestations include nodules, maculopapular rash, or, rarely, erythroderma. Peripheral edema, particularly periorbital and/or conjunctival, occurs relatively frequently in T-PLL [9,10]. There is no association with human T-cell lymphotropic viruses (HTLV-I/II) [11]. Prior to the use of pentostatin and alemtuzumab in clinical protocols, the outcome for T-PLL patients was exceedingly poor (median survival <1 year).