Atypical Extramedullary Acute Myeloid Leukemia in Infancy: Bilateral Testicular Swelling and Scalp Lesions at Diagnosis.

Acute myeloid leukemia (AML) is rare in infancy, with monocytic subtypes such as acute myelomonocytic leukemia often demonstrating extramedullary involvement. This report describes a 10-month-old male infant presenting with firm bilateral testicular enlargement and multiple parietal scalp nodules, accompanied by leukocytosis and circulating blasts in peripheral blood. Bone marrow examination confirmed French-American-British (FAB) M4 AML. Scrotal ultrasound demonstrated heterogeneous masses, and computed tomography identified scalp chloromas without bone erosion. The patient received AML chemotherapy, resulting in resolution of extramedullary lesions and achievement of remission. This case underscores the importance of early hematologic evaluation in infants with bilateral testicular masses to prevent misdiagnosis. It illustrates the rare occurrence of concurrent testicular and scalp chloromas as the initial manifestation of infant AML.