Neoplasias of the colorectal crypts.

Colorectal cancers are often preceded by noninvasive neoplasias arising in the surface epithelium, namely tubular, tubulovillous and villous adenomas. That neoplasias may also arise in the colorectal crypts is less well known. Between 1998 and 2002, colonoscopies, rectoscopies and colorectal surgical specimens from 8647 patients were received at this Department for histological diagnosis. The material included 502 adenomas, 865 invasive tumours and 221 cases of ulcerative colitis (UC). The following cryptal lesions were investigated: (a) neoplasias arising in the crypts, (b) neoplasias possibly arising in the crypts and (c) cryptal lesions alleged to be premalignant. Over the 5-year period, the most frequent phenotype encountered was single crypt dysplasia (in all 5 colectomies from familial adenomatous polyposis patients), followed by serrated adenomas (11.2%), hyperplastic polyps (8.4%), dysplasia in UC (6.3%), pure carcinoid tumours (1.7%), signet ring cell carcinoma (1.1%), adenocarcinoid tumours (0.2%) and de novo carcinomas (0.1%). In this survey, no case of Paneth cell adenoma or of cryptal neoplasia in lymphoid-associated mucosa (also known to originate from the crypts) was found. Hence, it was demonstrated that several neoplasia phenotypes actually arise in the colorectal crypts. The awareness that colorectal neoplasias may evolve from that particular cellular domain may cast more light on the understanding of the complex mechanisms of colorectal carcinogenesis.