Prolymphocytic Progression in Chronic Lymphocytic Leukemia Without Richter Transformation: An Eighteen-Year Clinical-Diagnostic Correlation.

Chronic lymphocytic leukemia (CLL) is an indolent neoplasm of small, mature B lymphocytes characterized by clumped chromatin and scant cytoplasm. A minor subset of neoplastic cells may exhibit prolymphocytic morphology, with prominent nucleoli and moderate cytoplasm. An increased proportion of prolymphocytes in peripheral blood often correlates with an accelerated or aggressive disease course, distinct from Richter transformation (RT), which more commonly manifests as diffuse large B-cell lymphoma and requires intensified therapy. We report an 18-year clinical course of CLL in a 57-year-old man that evolved to prolymphocytic progression without transformation to large-cell lymphoma. Serial morphological assessments revealed a steady increase in prolymphocytes compatible with prolymphocytic progression in CLL and excluded RT. At the final assessment, 70%-80% of circulating lymphocytes exhibited prolymphocytic morphology, fulfilling criteria for prolymphocytic progression and reclassification as accelerated CLL. Accompanied immunophenotypic and IgH gene rearrangement findings confirmed CLL clonality. This case underscores the diagnostic and prognostic importance of recognizing prolymphocytic progression and integrating morphology with immunophenotypic and molecular data in the longitudinal management of CLL.