Composite glandular-carcinoid tumors of the colon and rectum. Report of two cases.

Composite glandular-carcinoid tumors of the large bowel are rare. We describe two cases that appeared to be at a relatively early stage in their development. Each of these cases was a composite colorectal adenoma-carcinoid--an entity that has not previously been described. There was no evidence of inflammatory bowel disease (IBD) in either of these cases; and a review of the literature on composite adenocarcinoma-carcinoid neoplasms of the colon and rectum revealed only two cases that arose in a background of IBD. Thus, despite the association of IBD, especially long-standing ulcerative colitis, with epithelial dysplasia and mucosal endocrine cell hyperplasia, respectively, we believe that other factors more significant than IBD may be operative in the genesis of composite glandular-carcinoid tumors of the large bowel. Further documentation of these tumors is needed in order to better appreciate their clinicopathologic manifestations and associations.