Objective
Warthin's tumor (WT) is the second commonest benign neoplasm of the parotid gland and constitutes about 14% of all epithelial tumors of the parotid gland. The coexistence of Warthin's tumor with granulomas is under-investigated. The pathogenesis of the granulomatous changes in WT, especially sarcoid-like granulomas, remains unclear. We investigate the specificity of EZH2 in metaplastic WT and classic WT.
 
Method
We retrospectively evaluated 48 patients with metaplastic WT and 60 patients with conventional WT who had undergone curative surgery between November 2016 and December 2021. Patients with WT were informed about the study and consented to participate. Malignant transformation and collision lesions were excluded from all 108 cases.
Results
Cases of conventional WT did not show a granulomatous reaction. Twelve cases out of 48 metaplastic WT revealed mild to severe granulomatous reactions in the lymphocytic stroma. Of these, a case showed a tuberculous reaction, and two cases revealed sarcoid-type granulomas composed of dense aggregates of epithelioid histiocytes and occasional Langhan's giant cells.
Advances in Knowledge
This is the first study to report EZH2 as a specific marker for granulomatous WT. Strong expression of EZH2 was clinically correlated to a past history of either pulmonary tuberculosis or sarcoidosis.