B-cell Prolymphocytic Leukemia : Differential
Differential Diagnosis: B-cell prolymphocytic leukemia (B-PLL) needs to be distinguished from leukemic phase of mantle cell lymphoma, splenic marginal zone lymphoma (SMZL), hairy cell leukemia (HCL), and chronic lymphocytic leukemia with increased prolymphocytes. Prolymphocytes lack cytoplasmic hairy projections and villi differentiating B-PLL from HCL variant and SMZL. However, morphology alone is insufficient and accurate diagnosis of B-PLL requires immunophenotypic and genetic analysis of peripheral blood. B-PLL shows strong surface IgM/IgD, bright surface kappa or lambda light chain, and strong positivity for CD20 and other B-cell markers. It is negative for CD11c, CD103, CD10, CD25, cyclin D1, and SOX11. These markers help differentiate it from other lymphoid neoplasms with leukemia presentation such as T-cell prolymphocytic leukemia, mantle cell lymphoma, follicular lymphoma, lymphoplasmacytic lymphoma, and hairy cell leukemia. The image shows a sheet of prolymphocytes from a case of B-PLL involving lymph node.