Adenoid cystic carcinoma of the salivary glands: an immunohistochemical analysis

Adenoid cystic carcinoma is a specific variant of adenocarcinoma with a characteristic cribriform appearance. The tumor may arise from salivary glands and various other sites, but the origin and cellular composition of this unique neoplasm have been controversial. A potential use of immunohistochemistry is to provide additional information on the origin of various cellular components of tumors by comparing them with corresponding normal tissues. Immunohistochemical distributions of carcinoembryonic antigen (CEA), epithelial membrane antigen (EMA), keratin, low molecular weight keratin (54 kd), S100 protein, muscle-specific actin, laminin, and type IV collagen were evaluated in 20 adenoid cystic carcinomas arising in major and minor salivary glands. Anti-CEA, anti-EMA, anti-keratin, and anti-S100 antibodies strongly stained cells lining true lumina. Muscle-specific actin, a marker for myoepithelial cells, was found in lining cells of pseudocysts, in tumor cells proper, and in nonluminal cells with a tubular growth pattern. A monoclonal antibody against 54 kd keratin stained almost all cells in the neoplasms. In pseudocysts, replicated basal lamina reacted with antisera to laminin and to type IV collagen. The present study demonstrates that there are at least two populations of tumor cells in adenoid cystic carcinoma: luminal cells that express CEA and EMA, thus indicating their ductal character, and nonluminal cells that express muscle-specific actin characteristic of myoepithelium.