Nuclear ß-catenin expression in basal cell adenomas of salivary gland.

BACKGROUND: Nuclear localization of ß-catenin is known in a wide variety of human neoplasms; however, there are few reports in basal cell adenoma of the salivary gland. Our objective was to confirm the nuclear localization of ß-catenin in basal cell adenoma and to examine whether nuclear ß-catenin expression could be a useful marker in the diagnosis of basal cell adenoma. METHODS: To evaluate the nuclear localization of ß-catenin in basal cell adenomas, immunohistochemistry (IHC) and mutation analysis of CTNNB1 were performed in 22 and 21 cases, respectively. Mutation analysis of CTNNB1 in exon 3 was performed by DNA direct sequencing. In a comparative study, IHC for ß-catenin was also performed in 157 other salivary gland tumors. RESULTS: Nuclear ß-catenin expression was examined in 22 basal cell adenomas; scores were 2+ in 18 cases (81.8%), 1+ in three cases (13.6%), and 0 in one case (4.5%). Expression was localized in the basaloid myoepithelial cells. CTNNB1 mutation analysis was performed in 21 basal cell adenomas; mutations, including I35T and T41P, were detected in 11/21 (52%) cases. In comparison with other salivary gland tumors, one of three basal cell adenocarcinomas showed nuclear ß-catenin expression, whereas there was no nuclear ß-catenin expression in 154 other salivary gland tumors. CONCLUSIONS: We demonstrated nuclear ß-catenin expression and activation of the CTNNB1 gene in basal cell adenoma. Although nuclear ß-catenin expression may be unable to distinguish basal cell adenoma from basal cell adenocarcinoma, it should be a helpful marker in the diagnosis of basal cell adenoma.