Oncocytic neoplasms of the parotid gland. Differential diagnoses, clinical course, and overview of the literature

Background and objective. Oncocytic neoplasms of the salivary glands are rare. Patients/methods. We report on seven cases of oncocytic neoplasms of the parotid gland tone multifocal nodular oncocytic hyperplasia, five oncocytomas, and one oncocytic carcinoma). Results. While the history, clinical presentation, and histology of a II oncocytic neoplasms showed no characteristic differences, intraoperatively the well-differentiated oncocytic carcinoma displayed an infiltrative, locally aggressive growth pattern. A local carcinoma recurring 7 years later corresponded to the primary tumor. There were no metastases. Immunohistochemistry revealed that all oncocytic neoplasms were positive for markers of cytokeratins (KI-1) and negative for markers of carcinoembryonal antigen (CEA), S-100 protein, and smooth muscle actin (SMA). In contrast to the benign neoplasms, the oncocytic carcinoma showed an increased rate of proliferating cells (MIB-1) and a strongly positive reaction with the antibody MA-903 against high molecular weight cytokeratins. Conclusions. In a review of the literature, we could identify a group of locally aggressive, low-grade oncocytic carcinomas with a considerably better prognosis, similar to that of our case. The therapeutic significance of these findings is discussed.