A subtype of follicular adenoma in the THYROID GLAND. The Hurthle cell tumor is composed predominantly (at least 75%) or entirely of oxyphil cells. Hurthle cell neoplasms can be divided into benign and malignant categories. Malignant Hurthle cell carcinoma usually appear in patients over 60 years of age and are radioresistant.

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.

Synonyms: Oncocytoma, Oxyphilic Adenoma, Adenoma, Oxyphilic, Hurthle Cell Tumor, Huerthle Cell Tumor