B-cell prolymphocytic leukemia after COVID-19 infection

A 63-year-old man with 4-year history of CD19⁺/CD5⁻/CD23⁻/CD25⁻/CD103⁻/CD10⁻ non-CLL (chronic lymphocytic leukemia) monoclonal B-cell lymphocytosis (14.5 × 10⁹/L) without lymphadenopathy/splenomegaly presented 3 weeks after COVID-19 pneumonia with a marked, stable increase of white blood cell count (128 × 10⁹/L) and huge splenomegaly (23 cm). The peripheral blood smear showed >80% prolymphocytes with mature chromatin and single nucleolus (panel A, May-Grunwald-Giemsa stain, original magnification ×400). The bone marrow biopsy was diffusely infiltrated by prolymphocytes (panel B, hematoxylin-eosin stain, original magnification ×400) CD20⁺ (panel C, immunoperoxidase, hematoxylin counterstaining, original magnification ×400)/CD79b⁺ but negative for CD200, CD5, CD23, CD10, MUM1-IRF4 (panel D, immunoperoxidase, hematoxylin counterstaining, original magnification ×400; arrows indicate positive normal plasma cells), CD103, cyclin-D1, SOX11, BRAF-V600E. The karyotype was 46,X-Y, add(7)(p15),?t(9;9)(q32p23), +mar1. Targeted sequencing showed mutations of TP53, CCND3, and S1PR2 genes.

The case is presented due to its unique, unexplained association with COVID-19 infection and because B-cell prolymphocytic leukemia (B-PLL), regarded as an entity in International Consensus Classification, has been deleted in the 5th edition of World Health Organization classification and renamed “splenic B-cell leukemia with prominent nucleoli,” a basket category that also includes hairy cell leukemia variant (HCLv). The cytological features and immunophenotype of tumor cells, lack of intrasinusoidal marrow involvement, and mutational analysis excluded B-CLL prolymphocytoid transformation, HCLv (usually CD103⁺/CD25⁺, MAP2K1-mutated), splenic marginal zone lymphoma, and leukemic mantle cell lymphoma. The patient was diagnosed with B-PLL and started on chemotherapy followed by ibrutinib.

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