Warthin's tumour of the parotid glands, adenomatous hyperplasia and oncocytic adenomatous hyperplasia of the intranodal heterotopic salivary glands: A comparative immunohistochemical assessment

Objectives: In adenomotous hyperplasia (AH) and oncocytic adenomatous hyperplasia (OAH) of the intranodal heterotopic salivary gland tissue and Warthin's tumours of the parotid glands, the expression of various intermediate filament proteins and other tissue markers in the epithelial components were compared, since they share common histopathological characteristics with both eosinophilic luminal cells and basal cells. Materials and Methods: Tissue specimens from 79 intraparotid and extraparotid cervical lymph nodes containing heterotopic salivary gland tissue and 10 Warthin's tumours of parotid glands were evaluated for the expression of cytokeratins, vimentin, actin, epithelial membrane antigen (EMA), S-100 protein, lysozyme (Ly), lactoferrin (La), α1-antichymotrypsin (α1-ACT), α1-antitrypsin (α1-AT), and human gastric and lung cancer antigens by using the three stage streptavidin-biotin immunoperoxidase method. Results and Conclusions: A similar profile of positive immunoreactivity for cytokeratins, EMA, Ly, La, α1-ACT, α1-AT and human lung and gastric cancer antigens was observed in the epithelial components of AH, OAH and Warthin's tumours, while vimentin, actin and S-100 protein were negative in all of them. The histopathological and immunohistochemical profiles of AH and OAH in the intranodal heterotopic salivary gland tissue were closely mimicked by the epithelial tumour cells in Warthin's tumours. These findings suggest that Warthin's tumours may sometimes, but not always, arise from the ductal cells of heterotopic salivary gland tissue included in the lymph nodes.