Warthin's tumor--epithelial cell differences.

An immunohistochemical technic to localize IgA and a histochemical technic to demonstrate beta-D-galactose and N-acetyl-S-galactosamine by peanut agglutinin are applied to paraffin-embedded sections of Warthin's tumor. The luminal layer of epithelium is positive for IgA, while the basal layer is positive for peanut agglutinin. The luminal layer epithelium apparently serves as the route through which IgA (derived from plasma cells in the lymphoid stroma) is secreted into the cystic spaces. The apical cytoplasmic staining for peanut agglutinin in the basal layer is uniquely different from the peanut agglutinin staining pattern in the normal parotid gland. We conclude that the two-layer epithelium of Warthin's tumor is different in morphology, biochemistry, and function.