Oncocytoma

Oncocytoma
Micrograph of a parotid gland oncocytoma (right of image). Normal parotid gland is also present (left of image). H&E stain.
Classification and external resources
Specialty
ICD-O	M8290/0
DiseasesDB	31956
eMedicine	med/1045
Patient UK	Oncocytoma
MeSH	D018249

Gross appearance of the cut surface of a nephrectomy specimen containing a renal oncocytoma. Note the rounded contour, the mahogany colour and the central scar.

An oncocytoma is a tumor made up of oncocytes, epithelial cells characterized by an excessive amount of mitochondria, resulting in an abundant acidophilic, granular cytoplasm. The cells and the tumor that they compose are often benign but sometimes may be premalignant or malignant.

Presentation

An oncocytoma is an epithelial tumor composed of oncocytes, large eosinophilic cells having small, round, benign-appearing nuclei with large nucleoli.

Oncocytoma can arise in a number of organs.

Renal oncocytoma

Main article: Renal oncocytoma

Salivary gland oncocytoma

Oncocytoma of the salivary gland. This lesion presented as a lateral anterior neck mass. At surgery, it was found to be a soft 3.0 × 2.1 × 1.8 cm tumor of the submandibular salivary gland. The photo shows the characteristic dark color of an oncocytoma, a rare type of benign neoplasm, at the left side of the image (the normal lobulated salivary gland tissue is to the right).

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.

Symptoms

Salivary gland oncocytomas are most common in ages 70–80, females, the parotid gland (85–90%), and are firm, slowly growing, painless masses of less than 4 cm. They may be bilateral.

Thyroid oncocytoma

Thyroid oncocytomas can be benign (adenomas) or malignant (carcinomas). Grossly, oncocytic adenomas are encapsulated, solid nodules with a characteristic brown cut surface. The gross appearance of a minimally invasive oncocytic carcinoma is indistinguishable to that of an adenoma, while widely invasive oncocytic carcinomas are obviously invasive macroscopically and display pervasive vascular invasion with multifocal involvement of the thyroid gland. There are no reliable cytologic features which distinguish oncocytic adenomas from carcinomas and the only criterion for a diagnosis of malignancy is the identification of transcapsular or vascular invasion.

Symptoms

Patients with thyroid oncocytomas present with a thyroid nodule, usually with normal thyroid function. If the tumor is big or invasive, there may be other symptoms such as difficulty swallowing or talking.

See also

• Kidney
• Renal cell carcinoma
• Hurthle cell

Additional images

• 

  Micrograph of a renal oncocytoma. H&E stain.

• Renal oncocytoma4.jpg

  Micrograph of a renal oncocytoma. H&E stain.