---

A rare case of squamous cell carcinoma ex pleomorphic adenoma in maxillary sinus is presented. The patient is a 50-year-old woman presenting with a slow-progressive swelling in left side of her face that she has noticed 2 years earlier. The lesion was not painful and caused asymmetry and mild exophthalmos. Microscopic examination revealed that the tumor was composed of two components partly of a pleomorphic adenoma and partly of a squamous cell carcinoma. Immunohistochemical examination for Ki-67 and SMA and mucicarmin staining were also done and confirmed the diagnosis of carcinoma ex pleomorphic adenoma. There is no evidence of recurrence 12 months after operation.