Obstructing carcinomas of the colon and rectum: clinicopathologic analysis of 40 cases.

A review of 40 cases of obstructing colorectal carcinoma selected from 1,786 cases of surgically resected colorectal carcinomas was undertaken. The average age of the patients was 63 years, and there were 22 women and 18 men. Twenty-three lesions (58%) arose in the sigmoid colon and nine (23%) in the transverse colon, and obstructing rectal carcinomas were significantly rare. All of the obstructing tumors displayed a circumferential growth, 32 being examples of the annular constricting type. Obstructive colitis was caused by a combined lesion in only three cases. Microscopic characteristics of the obstructing carcinomas were as follows: 1) invasion of the whole thickness of the colorectal wall by the malignant tissue, 2) complete discontinuance of the muscularis propria in the affected area, 3) striking fibrous stromal reaction in the tumor, 4) upward rising, not descending, of both stumps of the discontinuous muscularis propria, 5) infiltrative growth of the tumor into the subserosa with scar-like fibrosis. It is indicated from the present study that obstructing carcinomas have features promising construction of the bowel lumen, but patients with such a tumor are not appreciably different in prognostic, histologic nor immunohistochemical aspects from those with a non-obstructing carcinoma.