Carcinosarcoma Arising from Mixed Tumor of the Parotid Gland: A case report

ABSTRACT

A case of true malignant mixed tumor of the parotid gland is reported. The tumor, occuring in a 55-year-old man, started to grow rapidly after a long history of parotid mass. Total parotidectomy was carried out and the resected tumor measured 5x4x3 cm with a cut surface showing grayish-white solid and myxoid appearance. Microscopically, the tumor had both carcinomatous and sarcomatous elements, the former consisting of undifferentiated carcinoma with focal areas of ductal differentiation and the latter consisting of pleomorphic sarcoma with chondrosarcomatous differentiation. A remnant of benign pleomorphic adenoma could also be identified. Immunohistochemical study demonstrated focal cytokeratin reactivity in the carcinoma cells and vimentin in sarcomatous elements. It is assumed from these clinical and histological findings that the tumor had transformed from a pre-existing benign pleomorphic adenoma.