Intracapsular carcinoma ex basal cell adenoma of the parotid gland.

Malignant transformation of basal cell adenoma is extremely rare. We report the case of a 63-year-old Chinese woman, who had noticed a slowing growing mass in her right parotid gland with slight pain for 1 month. Based on physical and ultrasound examinations, a diagnosis of benign salivary gland tumour was made before the surgery. A frozen biopsy was performed, and the diagnosis was basal cell adenoma, with the tumour cells infiltrating the capsule. Routine histopathological examination was performed after the surgery, and a final diagnosis of intracapsular basal cell adenocarcinoma ex basal cell adenoma was made. The patient received a further total parotidectomy and recovered well without any evidence of facial nerve palsy. This case suggests that during frozen biopsy, adequate sectioning including the capsule should be made. With regard to the treatment, we suggest a complete excision of the tumour with tumour-free margins, without any additional auxiliary therapy.