Embryonal and alveolar rhabdomyosarcoma of parameningeal sites in adults: a report of 13 cases.

This study reports 13 adult parameningeal rhabdomyosarcomas. Ages ranged from 18 to 86 years. Nine lesions were alveolar, 3 were embryonal, and 1 could not be further classified. All cases were positive for desmin and/or myogenin and 1 tumor was strongly positive for cytokeratin. PAX3-FKHR or PAX7-FKHR fusion transcripts or FKHR breaks were identified in 5 cases confirming a diagnosis of alveolar rhabdomyosarcoma. Three cases were negative supporting a diagnosis of embryonal rhabdomyosarcoma. A total of 10 patients were treated with chemotherapy and radiation. Three patients are alive with no disease, 3 are alive with disease, 3 died of disease, and 4 patients are lost to follow-up. Adult sinonasal rhabdomyosarcoma is uncommon and should be considered in the differential of sinonasal neoplasms. Disease can occur in the elderly. Desmin and myogenin can aid in the diagnosis but cytokeratin reactivity can be seen and care must be taken not to diagnose carcinoma.