Salivary gland basal cell and canalicular adenomas - Immunohistochemical demonstration of myoepithelial cell participation and morphogenetic considerations

Objective.-To evaluate cellular composition of salivary gland adenomas usin g 3 monoclonal antibodies that recognize a smooth muscle phenotype confirme d to be sensitive for myoepithelial differentiation. Design.-Immunohistochemical evaluation of 25 salivary gland basal cell and canalicular adenomas, Setting.-Archival pathology material from the files of Henry Ford Hospital, Detroit, Mich, and the University of California at San Francisco. Results.-All basal cell adenoma variants exhibit some degree of myoepitheli al cell participation with periductal, epithelioid, and spindled (stromal-l ike) morphologic structures. Only the canalicular adenomas, even if mixed w ith trabecular and solid patterns, are devoid of staining with these 3 anti bodies, suggesting an adenoma composed exclusively of ductal luminal cells. Conclusions.-There is an overlapping histomorphologic and common cellular c omposition of the basal cell adenoma variants with other recognized adenoma s, such as pleomorphic adenoma and myoepithelioma. Relative differentiation toward 3 cell phenotypes (ductal luminal, basal, and myoepithelial) and th e character of extracellular matrix production in varying proportions by th e neoplastic myoepithelial cells distinguishes the spectrum of salivary gla nd adenomas identified in current classification schemes.