Pleomorphic Adenoma of the Parotid Gland

A 20-year-old woman presented with a painless left facial mass that had slowly enlarged over the previous 2 years. There was no facial numbness or weakness. Her medical history was unremarkable, and there was no recent weight loss.

Physical examination revealed a well-circumscribed, firm, 2.5-cm mass that was located just inferior to the left pinna in the area of the left parotid. There was no cervical lymphadenopathy. A fine-needle aspiration biopsy was performed. Histologic evaluation revealed multiple islands of adenomyoepithelial cells immersed in a myxochondroid stroma, consistent with pleomorphic adenoma. A left parotid lobectomy was performed. The postoperative course was uneventful.

Alexander K. C. Leung, MD, and Wm. Lane M. Robson, MD, of Calgary, Alberta, advise that approximately 80% of parotid tumors are benign.¹ Pleomorphic adenoma is the most common salivary gland tumor; it accounts for about 70% of benign tumors of the salivary gland (followed by Warthin tumor).¹ Pleomorphic adenoma has a relatively high recurrence rate and the potential for malignant transformation. The rate of recurrence is reported to be 4% to 45%, depending on the surgical technique used. Pleomorphic adenomas recur more frequently when removed by enucleation. Recurrence of the tumor usually occurs within 10 years after surgical excision. Depending on the size and extent of the tumor, parotid lobectomy, superficial parotidectomy, or extracapsular tumor dissection are the treatments of choice. Potential complications of surgery include facial nerve palsy, neuroma formation, and gustatory sweating (Frey syndrome).