Levine et al. [7] reported that secretory carcinoma are characterized by a web-like metachromatic extracellular material, which is quite different from the thick mucin (blue on Giemsa staining) observed in Warthin tumors and low-grade mucoepidermoid carcinomas, and also different from the characteristic fibrillary matrix of pleomorphic adenoma. This evidence concerns the gene MUC5AC and Warthin tumor.