“Clear cell” oncocytoma of salivary gland

For the most part, clear cell neoplasms of the salivary glands are adenocarcinomas of at least low-grade malignant potential. However, a rare benign clear cell tumor of major salivary glands can be distinguished as a histologic variant of oncocytoma and oncocytosis. Ten such cases have been identified in the files of the Armed Forces Institute of Pathology (Washington, DC). Eight patients were women, and nine of the lesions involved the parotid gland. All of the patients were middle-aged or older adults. The light-microscopic morphology and the phosphotungstic acid-hematoxylin (PTAH), PAS, and mucicarmine staining patterns were consistent with oncocytoma and oncocytosis. Transitions from typical eosinophilic oncocytes to clear cells were evident. Electron microscopy and histochemistry demonstrated that the clear cytoplasm seen by light microscopy was primarily due to artifact and intracytoplasmic glycogen. Mitochondria were the preponderant cytoplasmic organelles. Two patients were known to have experienced recurrent lesions.