T-cell Prolymphocytic Leukemia with CD4⁺8⁺25⁺ Phenotype in a Patient Presenting with Venous Thrombosis in the Lower Leg

Abstract

A 58-year-old man was referred to our hospital because of painful swelling in the left lower leg and leukocytosis in January 1999. Moderate hepatosplenomegaly but no lymph node swelling was observed. Marked leukocytosis (leukocytes 44.9×10⁴/μl with 95% morphologically prolymphocytes) and thrombocytopenia were detected. The surface phenotype of the leukemia cells was CD1^-2⁺3⁺5⁺7⁺4⁺8⁺25⁺. Magnetic resonance imaging revealed dilated veins in the left lower leg. An abnormal 47XY, +22 karyotype was detected in 1/20 cells. Tests for HTLV-I antibody were negative. A diagnosis of T-cell prolymphocytic leukemia (T-PLL) was made on the basis of data including cytochemical and electron microscopic findings. Although 2 courses of chemotherapy comprising vincristine, cyclophosphamide, and prednisolone improved the venous thrombosis in the leg, the leukemia cells were refractory to chemotherapy. To prevent the recurrence of venous thrombosis due to leukostasis, the patient underwent repeated leukapheresis. The leukocyte count was maintained at around 20.0×10⁴/μl after total 7 courses of leukapheresis, one course of which comprised 7l of extracorporeal circulation. In addition to the rare presentation of venous thrombosis, the CD4⁺8⁺25⁺ phenotype observed in this case is rare in patients with T-PLL.