Multinodular oncocytoma of the parotid gland: a benign lesion simulating malignancy.

Oncocytomas of the salivary glands are rare. Occasionally, they are multinodular, which imparts a malignant appearance. Only eight such cases have been reported, and an additional case is reported herein. Dense cytoplasmic acidophilia is an important clue in the identification of the lesion. When this feature is lacking, the lesion may be mistaken for the more aggressive acinic cell tumor. Histochemical strains are not as useful as generally believed. Electron miscroscopy confirms the diagnosis by demonstrating an abundance of mitochondria. The presence of oncocytic cellular buddings from the intercalated ducts and ductules surrounding the tumor and the lobular oncocytic transformation were important aids in the recognition of multinodular oncocytoma.