An oncocytoma is a kidney or salivary gland tumor made up of oncocytes, a special kind of cells.
An oncocytoma is an epithelial
tumor composed of oncocytes, large eosinophilic
cells having small, round, benign-appearing nuclei
with large nucleoli
. It is thought to arise from the intercalated cells of collecting ducts
of the kidney. It represent 5% to 15% of surgically resected renal neoplasms
. Ultrastructurally, the eosinophilic cells have numerous mitochondria
. In gross
appearance, the tumors are tan or mahogany brown, well circumscribed and contain a central scar. They may achieve a large size (up to 12 cm in diameter). Renal oncocytoma is considered benign
, cured by nephrectomy
. There are some familial cases in which these tumors are multicentric rather than solitary.
The salivary gland oncocytoma is a well-circumscribed, benign neoplastic growth also called an oxyphilic adenoma. It comprises about 1% of all salivary gland tumors. The histopathology is marked by sheets of large swollen polyhedral epithelial oncocytes, which are granular acidophilic parotid cells with centrally located nuclei. The granules are created by the mitochondria.
Most cases are asymptomatic, discovered incidentally (by chance) on a tomography or ultrasound of the abdomen. Following are some of the possible symptoms : Hematuria, flank pain, abdominal mass.
Salivary gland oncocytomas are most common in ages 70-80, females, the parotid gland (85-90%), and are firm, slowly growing, painless masses of < 4 cm. They may be bilateral.