Oncocytic metaplasia in inflammatory fibrous hyperplasia: Histopathological and immunohistochemical analysis.

Oncocytic metaplasia (OM) is not a well-known feature in inflammatory fibrous hyperplasia (IFH) lesions, although it may be common, as proposed in our previous study about this lesion. In the present paper, we assessed the histopathological and immunohistochemical features of 18 cases of IFH containing OM areas. All the samples were examined on haematoxylin and eosin stained sections and cytokeratins (AE1/AE3, 34betaE12, CK5, CK7, CK8, CK13, CK14 and CK19), CD15, CD20, CD68, CD45Ro, and LCA primary antibodies were used. The vast majority of IFH occurred in women (n=14) and the most common site of presentation was the buccal vestibule. Oncocytic and salivary duct cells showed uniform immunoreactivity for AE1/AE3, CK7, CK8 and CK19. CD45Ro+ T-lymphocytes were the most common inflammatory cells surrounding the OM areas followed by CD20+ B-lymphocytes. These findings suggest that oncocytic cells present in IFH might develop from salivary duct epithelium, and T-lymphocytes might play an important role in its etiopathogenesis.