Carcinosarcoma of the parotid gland: an unusual case with large-cell neuroendocrine carcinoma and rhabdomyosarcoma.

We report a case of carcinosarcoma of the parotid gland in a 72-year-old Japanese man. The patient noticed a rapidly enlarging hard mass in the right parotid gland. He underwent radical parotidectomy with cervical lymph node dissection. The resected tumor measured 3.5 x 4.5 cm and histopathologically showed carcinomatous and sarcomatous components. The carcinomatous component consisted of large-cell neuroendocrine carcinoma (LCNEC), squamous cell carcinoma and adenocarcinoma not otherwise specified, while the sarcomatous component included spindle cell sarcoma not otherwise specified, so-called myxosarcoma and rhabdomyosarcoma. The LCNEC component was predominant within the whole tumor. The diagnoses of LCNEC and rhabdomyosarcoma were also confirmed immunohistochemically. With regard to histopathogenesis, based on the lack of histopathological evidence and antecedent history of pleomorphic adenoma, we considered the present case to be de novo, not expleomorphic adenoma.