Immunohistochemical analysis of basal cell adenocarcinoma.

Basal cell adenocarcinoma is a recently defined category of salivary gland neoplasms. As the terminology implies, this group of tumors has many histopathologic features that are similar to the more well-known basal cell adenomas. To better characterize these tumors, 23 basal cell adenocarcinomas were reviewed and compared with 11 basal cell adenomas with the use of light microscopic and immunohistochemical methods. Evaluation of cytokeratin, S-100 protein, glial fibrillary acidic protein, carcinoembryonic antigen, epithelial membrane antigen, smooth muscle actin, vimentin, B72.3, Ber-EP4, and milk fat globulin immunoreactivity was performed. Parallel to the morphologic similarity, the immunoprofiles of the basal cell adenocarcinoma and basal cell adenoma were quite similar. Both tumors showed reactivity patterns indicative of ductal epithelial and myoepithelial differentiation. In addition, reactivity to some polymorphic epithelial mucins was observed, which suggested glandular differentiation. The identification of antigens found normally in myoepithelial and epithelial cells supports the concept that these tumors are derived from pluripotential salivary gland epithelial cells. The comparable immunohistochemical profiles imply evolvement from similar cell lines and lead us to conclude that distinction between the two is not possible on the basis of these findings.