A usually benign glandular tumor composed of oxyphil cells, large cells with small irregular nuclei and dense acidophilic granules due to the presence of abundant mitochondria. oxyphil cells, also known as oncocytes, are found in oncocytomas of the kidney, salivary glands, and endocrine glands. In the thyroid gland, oxyphil cells are known as Hurthle cells and Askanazy cells.