Carcinoma ex pleomorphic adenoma of the palate--a case report.

A case of squamous cell carcinoma ex pleomorphic adenoma in a palate is presented and comments on diagnostic criterias are described. The patient was 36-year-old male presenting with an ovoid elevated palate mass for 6 months. The tumor located in the junctional area of soft and hard palate. The mucosa was diffusely ulcerated and the mass focally tightly adherent to adjacent tissue. The initial cytologic and pathological diagnosis by fine needle aspiration biopsy and open biopsy was benign pleomorphic adenoma. After total removal, histologic examination revealed that tumor was composed partly of benign pleomorphic adenoma and partly of an squamous cell carcinoma component with areas of necrosis and capsular invasion. Immunohistochemical staining in the carcinoma area revealed positive reaction for low and high molecular weight cytokeratin, and epithelial membrane antigen, but negative for desmin, actin, GFAP and S-100 protein. In situ hybridization using biotinylated Epstein-Barr virus probe was done and the neoplastic cells were negative. Our case in an unusual partially encapsulated carcinoma ex pleomorphic adenoma in the palate and is not related in EBV infection.