Oncocytic lesions of the neuroendocrine system

Oncocytic tumors are rare tumors that have been described in many organs throughout the body, mainly in salivary, parathyroid, thyroid, and adrenal glands and in the kidney. A wide spectrum of benign and malignant oncocytic tumors can arise in various organs of the neuroendocrine system. They are usually defined as tumors that are composed predominantly or exclusively of oncocytic cells. A majority of these tumors are benign; however, in some endocrine organs such as the thyroid the diagnosis of oncocytic/Hürthle cell carcinoma portends a more aggressive clinical course than non-Hürthle cell follicular carcinoma. Therefore, it is important to follow strict criteria to diagnose and differentiate between benign and malignant oncocytic tumors. In this review we will discuss the clinicopathologic features of various oncocytic tumors of the endocrine glands.