Primary tumors of the external and middle ear. III. A clinicopathologic study of embryonal rhabdomyosarcoma.

Embryonal rhabdomyosarcoma of the middle ear-mastoid is a highly lethal neoplasm of childhood in most cases, which clinically simulates a chronic infection. Extensive hemorrhage and necrosis in the biopsy specimen may obscure and often delay the diagnosis. Two of the six embryonal rhabdomyosarcomas in this study showed histologic evidence of differentiation. These same two patients were the only long-term survivors. Similar examples of "differentiated" embryonal rhabdomyosarcomas of the middle ear-mastoid with prolonged survival have been recorded individually in the literature. Therapeutic implications of this finding have been discussed.