Crohn's disease with adenocarcinoma and dysplasia. Macroscopical, histological, and immunohistochemical aspects of two cases.

We present two cases of small-bowel adenocarcinoma and dysplasia in patients with longstanding Crohn's disease. In one case, the dysplasia and cancer were exclusively located in the terminal ileum, whereas in the other case, several cancers were found from the ileum toward the transverse colon. In both cases, we found a clinically unsuspected Dukes C1 mucinous adenocarcinoma together with large foci of polypoid villous dysplasia or with multifocal high-grade dysplasia and intramucosal carcinoma. Immunohistochemical staining for carcinoembryonic antigen (CEA) revealed a different staining pattern in various diseased areas. The intensity of CEA staining paralleled the histologic degrees of dysplasia and neoplasia. Cytokeratin expression was disturbed in inflamed mucosa, and it was more pronounced in high-grade dysplasia and invasive carcinoma. We conclude that the presence of dysplasia in an intestinal biopsy of a patient with Crohn's disease should arouse the pathologist's suspicion of carcinoma and force him or her to take multiple sections from strictures and polypoid lesions, especially since the clinical symptoms of a carcinoma may be obscured by the symptoms of inflammatory bowel disease. Immunohistochemical staining with CEA and cytokeratin are useful in the objectivation of dysplasia.