Oncocytoma

Background

These are benign salivary gland tumors accounting for 1% of all salivary gland tumors. The majority (84%) occur in the parotid gland and are found in even distribution between men and women usually in their 6th decade. There is an association with previous radiation exposure, sometimes up to 40 years prior to discovery of the tumor. In these patients, tumors usually present 20 years earlier than non-exposed patients. These tumors are well-circumscribed and have a brown lobular cut surface.

These tumors follow a benign course but may recur in 7% of cases resulting in bilateral and multiple tumors. Extremely rare examples of oncocytic carcinoma have also been identified.

Under the microscope, these tumors are composed of oncocytes, cells having abundant eosinophilic staining cytoplasm with a slight granularity. This appearance is caused by numerous mitochondria. In recurrent tumors, there may be marked clear cell change and these tumors may be referred to as clear-cell oncocytoma. Occasional, reactive conditions within the salivary gland lead to oncocytic adenomatous hyperplasia. Histologically, they are identical to this tumor and distinction can be made clinically.

Sternberg S. Diagnostic Surgical Pathology. Third Edition. Lipincott Williams and Wilkins 1999.

Commonly Used Terms

Salivary glands

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Last Updated 4/1/2000