The patient was a 72-year-old man who had a diagnosis of polycythemia vera in 2010. A JAK2 V617F mutation was positive. Hydroxycarbamide (hydroxyurea) was started at 500 mg and gradually increased to 1250 mg daily. A review of the peripheral blood smear identified 5% circulating blasts, macrocytosis, and marked megaloblastic changes in WBCs. Interestingly, nuclear hypersegmentation was identified in eosinophils (panels A-C), basophils (panels D-F), and neutrophils (panels G-I).
Nuclear hypersegmentation of neutrophils, eosinophils, and basophils due to hydroxycarbamide (hydroxyurea)
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