Systemic rhabdomyosarcoma presenting as leukemia: Case report with ultrastructural study and reviews

A 20‐year‐old white male was initially suspected clinically and pathologically of having an acute lymphoblastic leukemic process because of fatigue, severe anemia, thrombocytopenia, a leuko‐erythroblastic peripheral blood picture, and a diffusely infiltrated bone marrow. Subsequent review of the bone marrow material indicated cytologic features consistent with either an embryonal, undifferentiated small cell mesenchymal malignancy or reticulo‐endothelial malignancy. Ultimately, the electron microscopic (EM) study of the tumor proved to be diagnostic of rhabdomysoarcoma. An extensive search for a primary site of rhabdomyosarcoma did not show any lesion, although the genitourinary region was clinically suspected. The clinical course was a rapidly downhill one with extensive bone and CNS involvement. The patient died 5 months later. An autopsy permit was not obtained. This case emphasizes the occasional tendency of rhabdomyosarcoma to masquerade as a hematopoietic malignancy at the time of presentation and the usefulness of EM study in confirming a diagnosis.