The Association of Warthin Tumor with Salivary Ductal Inclusions in Intra and Periparotid Lymph Nodes

A predominant theory of the much debated histogenesis of Warthin tumor (WT) is that it arises from heterotopic salivary ductal inclusions (SDI) in parotid lymph nodes (LN). If this were the case, we might expect to see an increased number of SDI in the lymph nodes of patients with WT compared to controls. To test this, we compared the prevalence of SDI in patients with WT versus those with pleomorphic adenoma (PA). Cases of WT and PA were retrieved from the case files of the Department of Pathology at the QEII Health Science Centre, Halifax, NS, Canada. We then compared the prevalence of SDI in parotid LN between patients diagnosed with WT versus PA. 46 WT and 52 PA met our inclusion criteria. WT was significantly associated with an older age at surgery (62.5 years vs 50.2 years, p = 0.001). 71.7 % of WT and 32.7 % of PA had inclusions in any LN. The presence of inclusion is a significant predictor for WT versus PA (p = 0.019). Where smoking status was available, 92.5 % of WT patients were smokers/ex-smokers, versus. 55.1 % of PA (p = 0.034 for current smokers). Among PA, 44 % of smokers had inclusions compared with 22.7 % of non-smokers. SDIs are more frequent in parotid LN from patients with WT than PA. The high proportion of smokers among WT patients is consistent with prior studies. The results support the hypothesis that WT arises from SDIs. Individuals with more SDIs may be predisposed to WT.