Carcinosarcoma (malignant mixed tumor) of the parotid: report of a case with a pure rhabdomyosarcoma component.

BACKGROUND: Carcinosarcoma or true malignant mixed tumor of the parotid gland is extremely rare, accounting for < 1% of all salivary gland malignancies.

METHODS: A 63-year-old woman presented with a 5-cm right parotid mass which was resected with a radical parotidectomy and infratemporal fossa dissection.

RESULTS: The tumor contained two distinctive histologic patterns, that of a poorly differentiated ductal carcinoma and a pleomorphic rhabdomyosarcoma. Additionally, a residual focus of pleomorphic adenoma was present peripherally. Immunohistochemical and electron microscopic studies confirmed the skeletal muscle differentiation.

CONCLUSIONS: The pattern of combined rhabdomyosarcoma and ductal carcinoma has not been previously reported and adds further evidence to the myoepithelial derivation of these tumors.