B-Cell Prolymphocytic Leukemia: A Survey of 35 Patients Emphasizing Heterogeneity, Prognostic Factors and Evidence for a Group with an Indolent Course

Abstract

We report a retrospective survey of 35 patients (18 males and 17 females) with B-Prolymphocytic leukemia (B-PLL) followed for a median of 63 months. Twelve patients fulfilled Galton's original clinical and hematological criteria, presented with prominent splenomegaly and hyperleukocytosis and showed rapid progression soon after diagnosis. Twelve cases with gradually increasing spleen size and prolymphocyte count had an indolent course. Seven of this group are alive 68 to 164 months after diagnosis, whereas five died from causes unrelated to PLL. Eleven patients who never developed impressive leukocytosis had a variable prognosis. In the group of 17 patients treated with chlorambucil and prednisone (CP) or cyclophosphamide, vincristine, prednisone (COP) 8 achieved a partial remission (PR) with a median response of 32 months. In the group of six cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) treated patients one achieved a complete remission and two PR (median response was maintained for 30 months). Three patients treated with 2CdA achieved good PR Six patients remained untreated. Median survival was 65 months and the probability of overall survival for 3, 5, and 10 years was 63%, 56% and 35%, respectively. Anemia < 11 g/dl and lymphocytosis > 100 × 10⁹/1 were predictors of shorter survival in this group of patients. Age over 70, gender, B-symptoms at presentation, spleen size, thrombocytopenia, low IgG and complement levels, presence of paraproteinemia and the pattern of bone marrow infiltrate were not significant. Our findings show that all B-PLL may not have such a poor prognosis as described in earlier reports. The existence of prior symptoms evolving gradually after years to obvious PLL and cases with mild prolymphocytosis could possibly lead to underdiagnosis of the entity. Identification and follow-up of such cases may suggest a different natural history, variable prognostic features and different survival curves for B-PLL patients. In the light of the above, we suggest that the therapeutic approach for B-PLL should always relate to the severity of the disease.

Key Words:

• prolymphocytic leukemia
• PLL
• 2CdA
• prognostic factors