Acquired Platelet Dysfunction in Atypical Chronic Myeloid Leukemia: A Case Report

Atypical chronic myeloid leukemia (aCML), now classified as myelodysplastic/myeloproliferative neoplasm with neutrophilia, is a rare myeloid neoplasm characterized by neutrophilia, dysgranulopoiesis, and the absence of BCR::ABL1.Hemorrhagic manifestations may be related to acquired platelet dysfunction despite a platelet count only marginally below the reference range.We report the case of an 86-year-old woman with aCML who presented with diffuse spontaneous ecchymoses and a history of hemopericardium.Laboratory evaluation revealed marked leukocytosis of 43.7 × 10⁹/L, bone marrow dysgranulopoiesis with 4% blasts, absence of BCR::ABL1, and pathogenic TET2 and KRAS mutations.Platelet aggregometry revealed acquired platelet dysfunction, with severely impaired responses to arachidonic acid and collagen despite a platelet count of 145 × 10⁹/L, only marginally below the reference range.Renal function was normal, and she was not taking aspirin or NSAIDs.Low-dose hydroxyurea and close monitoring resulted in clinical and hematological stabilization.This case highlights the importance of functional platelet testing in patients with aCML who present with bleeding manifestations that cannot be explained by the platelet count alone, where it may be a contributing factor.