Keratocystoma of the parotid gland.

An 18-year-old man had a painless, elastic, firm mass in his left parotid area that gradually increased in size over a period of 6 months. At the time of examination, the parotid mass was poorly mobile and 46 mm in size. Although fine needle aspiration cytology revealed no malignant findings, we suspected a malignancy because the movement of his left mouth angle was slightly impaired; facial nerve paralysis as a result of tumor invasion was suspected. A superficial parotidectomy was performed. The tumor had a strong adhesion to the subcutaneous tissue and facial nerve. Histologically, multiple, randomly distributed cystic structures containing keratinized lamellae were present. The cystic spaces were lined with stratified squamous epithelium lacking a granular layer, and no skin appendage was observed. We diagnosed this case as a keratocystoma. Keratocystoma of the parotid gland is a rare benign tumor with only 6 cases reported worldwide. This case is the first to describe facial nerve palsy in association with a keratocystoma.