Pathologic and imaging findings of an oncocytoma in the deep lobe of the left parotid gland.

Oncocytoma is a rare salivary gland tumour consisting of oncocytes with many hyperplastic mitochondria. It usually occurs in the parotid gland. Because the features of oncocytoma resemble those of other benign and low-grade-malignant salivary gland tumours, clinical diagnosis is often challenging. This report presents the pathologic and imaging findings of an oncocytoma arising in the deep lobe of the left parotid gland in a 66-year-old man. Oncocytoma was diagnosed on the basis of histological, magnetic resonance imaging, and scintigraphic findings. The tumour showed accumulation of technetium-99m pertechnetate and decreased signal intensity on both T1- and T2-weighted magnetic resonance images.