Sinonasal intestinal-type adenocarcinoma: immunohistochemical profile and comparison with colonic adenocarcinoma.

Sinonasal intestinal-type adenocarcinomas (ITAC), as their name implies, bear a striking resemblance to primary intestinal neoplasia. The value and limitations of immunohistochemistry in making this distinction have not been previously defined. We determined the immunohistochemical staining profile of 12 sinonasal ITAC and compared their staining with that of 12 histologically similar colonic adenocarcinomas. All ITAC stained for cytokeratin and epithelial membrane antigen. Additional positive reactions were as follows: B72.3, 11 of 12; Ber EP4, 11 of 12; Leu M1, 8 of 12; HMFG-2, 12 of 12; and BRST-1, weak staining in seven of 12 cases. All 12 ITAC were negative for vimentin, synaptophysin, and actin. Colonic carcinomas stained similarly for these markers. Three additional antigens differed in their expression in ITAC versus colonic tumors. Carcinoembryonic antigen was strongly present in only two of 12 ITAC, with focal positivity in six of 12 and no staining in four of 12 cases. In contrast, all 12 colonic adenocarcinomas were strongly positive for carcinoembryonic antigen. Chromogranin-positive cells were present and often numerous in nine of 12 ITAC, in contrast to only rare positive cells in three of 12 colonic tumors. Neuron-specific enolase was present in five of 12 ITAC but was absent from all colonic tumors studied. ITAC are less often and less strongly carcinoembryonic-antigen positive and more prone to exhibit divergent neuroendocrine differentiation. These features may be of some value in distinguishing ITAC and colonic metastases. Neuroendocrine differentiation in ITAC was associated with higher mortality. Of the five patients with ITAC having 1+ to 2+ chromogranin positivity, only one was free of disease.(ABSTRACT TRUNCATED AT 250 WORDS)