Immunohistochemical localization of WT1 in epithelial salivary tumors

The subcellular localization of WT1 is controversial and has received little attention in the epithelial tumors of salivary glands. Paraffin-embedded, surgical specimens from 80 salivary tumors were investigated by immunohistochemistry using a monoclonal, anti-WT1 antibody (6F-H2, Dako). Immunostaining was seen in 14/14 pleomorphic adenomas (PAs), 6/6 myoepitheliomas, 4/4 basal cell adenomas, 4/4 canalicular adenomas, 0/7 Warthin tumors, 0/1 oncocytoma, 1/6 acinic cell carcinomas (Cas), 0/11 mucoepidemoid Cas, 1/11 adenoid cystic Cas, 11/12 polymorphous low-grade adenocarcinomas (PLGAs), 1/2 Ca ex PA, 0/1 salivary duct Ca and 0/1 clear cell adenocarcinoma. Stained-cell subpopulations up to 90% were not uncommon in the benign tumors. Up to 80% of cells in PLGA could be stained. Staining was weak to intense and confined to the cytoplasm of preferentially non-luminal or adjacent to stroma cells. One adenoid cystic Ca showed nuclear staining. The results suggest that WT1 is often highly expressed in benign non-oncocytic salivary tumors whereas the malignant tumors show decreased expression, the exception being PLGA. The expression is usually cytoplasmic and associated with non-luminal cells. PLGA immunoreactivities could be useful in histological differential diagnosis.