B-lineage prolymphocytic leukemia as a distinct clinicopathologic entity.

Prolymphocytic leukemia (PLL) was described originally by Galton and his colleagues as a special variant of chronic lymphocytic leukemia (CLL) with distinct clinical and hematologic features. Subsequent authors have described considerable heterogeneity in the clinical and immunologic features of PLL but have not dealt in detail with pathologic descriptions of their cases. Consequently, one might question whether PLL represents one disorder or a heterogeneous group of disorders. Three patients who satisfied Galton's original diagnostic criteria for PLL were examined by pathologic and immunologic methods. The spleens of these patients showed distinctive pseudonodular pathologic features. The malignant prolymphocytes were characterized as B-lineage by the presence of surface IgM and IgD, the expression of HLA-DR antigen, the absence of E-rosette formation, and the absence of natural killer cell activity. The existence of B-lineage prolymphocytic leukemia is affirmed as a distinct entity with unique pathologic, clinical, and immunobiologic characteristics.