Colorectal Mini-De Novo Carcinoma: A Reality in Germany Too

Abstract

Based on Japanese case studies, we examined whether colorectal mini-de novo carcinoma also occurs outside Japan. We defined mini-de novo carcinomas as carcinomas infiltrating the submucosa, with a maximum diameter of 10 mm, and with no evidence of precursive adenomatous tissue. Between 1988 and 1994, we diagnosed carcinomas of this type in polypectomy and surgical resection specimens from 155 patients. These mini-de novo carcinomas did not differ from carcinomas arising from adenomas in terms of patient age (median 67.1 years), sex distribution (men: women 0.96:1), or location--they occurred primarily in the sigmoid (53%) and rectum (27.3%). Most of the mini-de novo carcinomas were macroscopically of the polypoid type (59.4%); flat, elevated carcinomas were also relatively frequent, including those with a central concave depression (21.9%) and those without a depression (12.3%). Histologically, all of the lesions without exception were adenocarcinomas (grade 1: 28.4%, grade 2: 65.8%, grade 3: 5.8%). There was carcinomatous invasion of submucosal lymphatic or blood vessels in 20%. Our analysis shows that colorectal mini-de novo carcinoma is not a purely Japanese phenomenon, and that these carcinomas are being diagnosed with increasing frequency as the awareness of their existence and macroscopic growth characteristics increases.