Abstract
Carcinoma ex pleomorphic adenoma（CXPA）is defined as a carcinoma that arises in the epithelial and/or myoepithelial component of a primary or recurrent pleomorphic adenoma（PA）. However, the histology of epithelial-myoepithelial carcinoma（EMC）in CXPA is extremely rare. We report a case of EMC arising from PA in the parotid gland. A 55-year-old man who underwent surgery twice for PA in the right parotid gland complained of recurrent right parotid swelling during a one-year follow-up period. Two-point magnetic resonance imaging revealed a tumor recurrence which was suspected as CXPA due to its rapid growing patterns. An extended resection of the parotid tumor followed by reconstruction using an anterolateral thigh flap was performed. The removed tumor was histologically diagnosed as CXPA. Postoperative radiotherapy was performed because of the inadequate surgical margin. CXPA accounts for 5-10％ in PA and the risk increases with time. It is sometimes difficult to make a diagnosis preoperatively even by performing fine-needle aspiration cytology. When rapid growth of the tumor is confirmed during follow-up of the PA, surgical management should be administered because of the possibility of malignant transformation.
