Oncocytic adenocarcinoma of the ovary

A case of ovarian adenocarcinoma mainly composed of oncocytes was studied by light and electron microscopy. Oncocytes, characterized by granular and eosinophilic cytoplasm by light microscopy possessed numerous mitochondria at the ultrastructural level. These oncocytes were classified into two types: typical and condensed oncocytes. Typical oncocytes seemed to be active, whereas condensed oncocytes were thought to be involved in a degenerative process. The two types of cells showed a close similarity to oncocytes in other organs (e.g., thyroid, parathyroid and salivary glands). This appears to be the first report of an ovarian oncocytic tumor.