Ossification in a soft tissue embryonal rhabdomyosarcoma.

We describe the previously unreported finding of ossification within a rhabdomyosarcoma of the extremity in the absence of bone destruction. Rhabdomyosarcoma is a highly malignant tumor but could not be radiographically differentiated from benign or other malignant causes of soft-tissue masses containing calcium. Definitive diagnosis and thus appropriate therapy requires prompt pathologic examination.