Oncocytoma and Oncocytic Carcinoma of the Salivary Glands, Single Institute Experience

Background : Oncocytic neoplasms of the salivary glands are rare and the differential diagnosis between oncocytic carcinomas (OCs) and oncocytomas is difficult.We present 5 cases of oncocytoma and 3 cases of OC of the salivary glands with clinicopathological and immunohistochemical comparisons.Methods : Eight cases of oncocytic neoplasms diagnosed at Asan Medical Center between 1998 and 2009 were reviewed for clinical data and histological features.Immunohistochemical staining for epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (Her-2), c-kit, p53, and Ki-67 was done.Results : Cytological differences between oncocytomas and OCs were not obvious, but unequivocal infiltrative growths were identified in 3 cases, rendering the diagnosis of oncocytic carcinoma.When the remaining cases were classified as oncocytomas, there was no difference in age, size, and clinical symptoms between oncocytomas and OCs.Two of 3 OCs showed strong membranous expression of c-kit, but all oncocytomas were negative.The proportion of p53positive cells was larger in OCs than oncocytomas.Her-2 or EGFR expression was absent, and Ki-67 labeling indices were less than 1% in all cases.Conclusions : An infiltrative growth pattern, strong membranous expression of c-kit, and an increased proportion of p53-positive cells are features that can differentiate OCs from oncocytomas of the salivary glands.