Adrenocortical oncocytoma exhibits distinct biological features from renal oncocytoma: A rare case report

Adrenocortical oncocytoma is a rare adrenal tumor. We report a 59-year-old Japanese woman with a right adrenal mass. The resected specimen showed a well-defined, mahogany-brown tumor measuring 4.3 cm. Microscopically, the tumor scored 0 under both the Lin-Weiss-Bisceglia system and the reticulin algorithm, indicating benignity. Immunohistochemical analysis revealed that tumor cells were positive for mitochondria and negative for BSND and ATP6V1G3. Ultrastructural examination found no uniform mitochondria in the cytoplasm of the tumor cells. The oncocytoma in this case may share more characteristics with an adrenal cortical adenoma than with a renal oncocytoma.