A pituitary adenoma in a 67-year-old man was characterized by abundant mitochondria and identified as an oncocytoma, which clinically and histologically appeared as a chromophobe adenoma. In addition to the numerous mitochondria within the neoplastic cells, structurally abnormal mitochondria were also present. Compared with other pituitary oncocytomas reported in the literature, abnormally structured mitochondria appear rare among the mitochondrial population of pituitary oncocytomas.
This paper is dedicated to Hans Orthner, M.D., on the occasion of his 65th birthday.