Superficial depressed early carcinoma that developed into protuberant advanced carcinoma in the transverse colon

A screening colonoscopic examination in a 70-year-old man revealed a nonpol ypoid type superficial depressed early carcinoma, about 2 cm in diameter, i n the transverse colon. The lesion was not resected and was observed becaus e of coexisting nonresectable hepatocellular carcinoma (HCC). Fifteen month s later, follow-up examinations revealed a polypoid type protuberant advanc ed carcinoma, about 6 cm in diameter, at the same site. Because complete re sponse of the HCC had been induced by transarterial embolization, the colon carcinoma was operatively resected. There is an indefinite concept that co lorectal carcinomas develop without substantial morphological changes, and no superficial depressed carcinoma that developed into a protuberant type a dvanced carcinoma has been reported. The case reported here provides eviden ce that some polypoid carcinomas arise from superficial depressed precursor s. There is some intermingling between the two postulated colorectal carcin ogenic pathways, the conventional polypoid pathway named the "adenoma-carci noma sequence", and the nonpolypoid pathway, including so-called "de-novo" carcinogenesis.