by Jason Wasserman MD PhD FRCPC
April 3, 2024

An oncocytoma of the salivary gland is a rare, benign (non-cancerous) tumor that arises from the salivary glands. The salivary glands produce saliva, which is important for digestion and maintaining oral health. There are three major pairs of salivary glands: the parotid glands, the submandibular glands, and the sublingual glands, along with hundreds of minor salivary glands located throughout the mouth and throat. Oncocytomas can develop in any of these glands but are most commonly found in the parotid gland.

Is oncocytoma of the salivary glands a type of cancer?

No. Oncocytoma is a benign (non-cancerous) type of salivary gland tumour.

What causes oncocytoma?

Most oncocytomas are sporadic, meaning the tumour develops without any known genetic or environmental risk factors. However, some oncocytomas may develop after radiation therapy.

What are the symptoms of oncocytoma?

Most oncocytomas present as a small painless lump over one of the salivary glands.

Microscopic features of this tumour

When examined under a microscope, oncocytomas are made up of large pink oncocytic cells. The cells are called oncocytic because the cytoplasm (body of the cell) is full of thousands of mitochondria, a type of cellular machinery that converts oxygen into energy. The oncocytic cells look pink when examined under a microscope because the mitochondria stick to eosin, a pink-coloured dye found in the hematoxylin and eosin (H&E) stain used by pathologists. The tumour may be described as well-circumscribed, meaning there is a clear border between the tumour and the surrounding normal salivary gland tissue.