A Rare Cause of Lymphocytosis

An asymptomatic 49-year-old female presented with lymphocytosis (11.1 × 109/L lymphocytes) and thrombocytopenia (128 × 109/L platelets), with no additional cytopenias or physical findings. The blood film revealed lymphocytes of varying morphology, including unusual cells displaying bilobed nuclei. Bone marrow biopsy revealed mild interstitial B-cell lymphocytosis that included foci of intrasinusoidal localization highlighted by CD20. Flow cytometry revealed a predominance of polyclonal B cells lacking additional antigenic aberrancies (peripheral blood and bone marrow).

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A rare cause of lymphocytosis

Source: Blood Journal

Image credits: ASH Image Bank