Carcinosarcoma of the Skin

A case of carcinosarcoma arising in the skin of the left arm of a 69-year-old woman is reported with a review of the literature. The tumor was composed of low-differentiated squamous cell carcinoma, which was intermingled with a pleomorphic sarcoma. The carcinomatous component had keratin and lacked vimentin, whereas the phenotype of the sarcomatous portion was the reverse. The former presented additionally focal expression of S-100 protein, which was lacking in other portions of the carcinoma. The phenotypic data, supplemented by p53 immunostaining, which was present in both components, suggest their common origin in this tumor.