A case of 'Crohn's carcinoma'

Abstract

A woman of 55 presented with a 4 wk history of right sided abdominal pain, nausea, and vomiting. At operation the appearances were those of Crohn's disease of the terminal ileum in a quiescent phase, and an excision of the affected portion of the ileum and part of the ascending colon was carried out. At pathologic examination the thickened portion of the ileum was stenosed, with irregular ulceration of the mucosa, and in the center of the most narrowed area there was an intramural abscess on the mesenteric border. The cecum and colon were normal. Carcinoma was not suspected on macroscopic examination. The histologic appearances were of Crohn's disease of the terminal ileum and appendix. In the area around the intramural abscess the picture was similar but with more severe ulceration; the epithelium was dysplastic. In all layers of the bowel wall, numerous acini were seen passing through to the serosal surface and in the muscle coats some of these acini were present in perineural spaces. Therefore, this was a moderately well differentiated adenocarcinoma of the ileum arising in an area of Crohn's disease, with, in the surface epithelium, dysplastic epithelium amounting to carcinoma in situ. The most important question in this case is whether the adenocarcinoma arose as a result of the Crohn's disease, or whether the 2 diseases occurred purely coincidentally. From the literature (table) some of the features of 'Crohn's carcinoma' are summarized, as are data from 8 cases of consecutive carcinomata of the small intestine ('carcinoma de novo'). In comparing both types of tumor differences have been found in the age at diagnosis, the site and the prognosis; the first 2 findings could be confirmed in the present case. In addition, there are 3 pathologic features which are distinct enough to warrant more emphasis than they have been given previously. These were not present in any of the 8 cases of carcinoma de novo examined, and are not mentioned in textbook descriptions of that tumor. The first feature is the 'invisibility' of the tumor. Of 33 cases in which sufficient detail has been given, the carcinoma was not suspected in 17 (51%), either at operation or on macroscopic examination. The second is the presence around the tumor of dysplastic epithelium which may amount in places to carcinoma in situ. This was noted in 7 out of 26 cases (27%). The 3rd finding is that of a peculiar pattern of invasion in which quite separate, discrete acini pass through the bowel wall in a manner reminiscent of endometriosis, although there is no stroma surrounding the acini. The rate of occurrence of this endometriosis like pattern of invasion is much more difficult to assess, but in 10 out of 26 cases (38.5%), something similar appears to have been present. The first 2 features are present commonly in carcinomata arising in chronic ulcerative colitis. The authors feel that 'Crohn's carcinoma' has sufficient differences from carcinoma de nove to conclude that it is a definite complication of Crohn's disease of the small bowel.