Monomorphic Adenoma

Epidemiology

Monomorphic adenomas are benign parotid tumors that constitute 2% of all parotid neoplasms. These tumors consist of a very regular epithelial component and a mesenchymal component that is typically seen in pleomorphic adenoma. These lesions can arise in any of the salivary glands but are most common in the superficial lobe of the parotid gland. The majority (80%) of the minor salivary gland tumors occur near the upper lip. Monomorphic adenomas may be slightly more common in females.

Clinical Findings

Patients usually complain of a slow-growing mass in the parotid region and are otherwise asymptomatic. Patients with the classic basal cell type of monomorphic adenoma usually present between 60 and 70 years of age. The membranous form usually presents a decade earlier.