Temporal bone findings in rhabdomyosarcoma with predominantly petrous involvement.

Temporal bone rhabdomyosarcomas are rare tumors that occur almost exclusively in children. They arise most commonly in the middle ear, from which they extend through the mastoid and petrous portions of the temporal bone, eventually invading the cranium. We report the histopathologic findings of a rhabdomyosarcoma with anterior and medial displacement, predominantly involving the petrous bone. Recognition and separate study of this type of tumor is clinically important. Predominantly petrosal rhabdomyosarcomas are less prevalent than similar lesions with lateral expansion and tend to develop significant ear symptoms late in the course of the disease. When first diagnosed, these lesions usually exhibit signs of intracranial extension, and consequently are less amenable to treatment and are more rapidly fatal.