Warthin-like mucoepidermoid carcinoma of the parotid gland: Clinicopathological observation and literature review.

Warthin tumor (WT)-like mucoepidermoid carcinoma resembles the histologic pattern of WT and pathologists unaware of this possibility may misdiagnose it as WT with squamous and mucous epithelium metaplasia or WT malignant transfer into mucoepidermoid carcinoma. The present study reported a case of a 41-year-old Chinese female with a solitary mass in the left parotid gland. In this case, microscopic observation revealed prominent lymph node stroma and multiple cystic structures similar to those seen in WT. However, it lacked the two layers of oncocytic epithelial tissue characteristic of WT. Furthermore, fluorescence in situ hybridization detected MAML2 rearrangement in the case. Considering the histological findings, this case was diagnosed as WT-like mucoepidermoid carcinoma. The present case report provides pathological and clinical features to differentiate it from WT malignant transition into mucoepidermoid carcinoma, WT with squamous and mucous epithelium metaplasia and non-sebaceous lymphadenoma-like mucoepidermoid carcinoma. In conclusion, WT-like mucoepidermoid carcinoma as a special subtype of mucoepidermoid carcinoma has special histological characteristics, which required further observations and more case reports to clearly define this variant.