Basal cell adenocarcinoma of the salivary gland : An ultrastructural and immunohistochemical study

The purpose of this study was to examine the ultrastructural and immunohistochemical characteristics of basal cell adenocarcinoma. Three cases of basal cell adenocarcinoma of the salivary glands were studied by means of light microscopy, electron microscopy, and immunohistochemistry. Some of the architectural tumor patterns encountered were solid, some were trabecular, and some were mixed. Ultrastructurally, solid areas were composed of nonluminal cells, some of which contained tonofilaments and well-formed desmosomes; tubulo-trabecular areas differentiated into both luminal and nonluminal cells. Both growth patterns were associated with the formation of excess basal lamina, marginally and between nonluminal cells. Myofilaments were infrequent in nonluminal cells of solid or trabecular areas. Cytokeratin (AE1/AE3) stained all 3 tumors, more peripherally in the solid pattern and usually centrally in the trabecular areas; vimentin stained all 3 tumors diffusely; smooth muscle actin (IA4) stained all 3 tumors but was mainly confined to peripheral tumor cells in both the solid and the trabecular growth patterns; epithelial membrane antigen and carcinoembryonic antigen stained 1 of the 3 tumors, predominantly in the luminal cells; p53 oncoprotein was focally positive in 2 of the 3 tumors; Ki-67 stained less than 5% of the tumor cells in all cases; and c-erb-B2 was uniformly negative in all cases. Staining patterns of cytokeratin and actin varied with the architecture of the tumor. Neither ultrastructural characteristics nor immunohistochemistry findings appear to distinguish basal cell adenocarcinoma from basal cell adenoma.