by Jason Wasserman MD PhD FRCPC
August 31, 2022
An oncocytoma is a non-cancerous type of salivary gland tumour. It is not capable of transforming into cancer over time. Most oncocytomas develop in the parotid gland, but they can be found in any of the salivary glands.
Most oncocytomas in the head and neck are slowly growing and are usually painless.
Pathologists use the word oncocytosis to describe multiple oncocytomas in the same salivary gland.
The diagnosis is usually made after a small sample of tissue is removed in a procedure called a biopsy or a fine needle aspiration. The diagnosis can also be made after the entire tumour is removed in a procedure called a resection. The tissue is then sent to a pathologist who examines it under a microscope.
Under the microscope, oncocytomas are made up entirely of large pink cells. Pathologists describe these cells as oncocytic or oncocytes. The cells connect to form two rows, nests, or sheets. The nucleus of the cell is typically round and a large clump of genetic material called nucleoli are usually seen in the centre of the nucleus. Some oncocytomas will have large spaces on the inside of the tumour. Pathologists describe these spaces as cysts. The cysts may be filled with fluid or tumour cells.