Childhood leukemia presenting as a diaphyseal radiolucency.

A 41-month-old black child with a symtomatic diaphyseal destructive lesion of the femur, and a corresponding area of increased uptake on a technetium99m bone scan, had an upper respiratory tract infection. An open biopsy was performed because of an initial clinical diagnosis of osteomyelitis, histiocytosis X or a round cell sarcoma. The biopsy showed numerous blast cells compatible with acute lymphocytic leukemia. Acute leukemia should be included in the differential diagnosis of symptomatic diaphyseal destructive lesions in children. A peripheral blood smear should be carefully interpreted prior to any other invasive diagnostic tests.