Exophytic signet-ring cell carcinoma of the colorectum.

Previous studies have assessed colorectal signet-ring cell carcinomas of the linitis plastica variant but not of the exophytic subtype. We retrospectively reviewed 20 cases of colorectal signet-ring cell carcinoma of the exophytic subtype (greater than 50% signet-ring cells). The patients ranged in age from 14 to 79 years (mean, 51.8 years); 10 were male; 17 were white; and three were black. Ten tumors were colonic (eight, right sided; two, left sided) and 10 were rectal; seven were stage B and 12 were stage C. One patient presented with distant metastases. Eleven of 16 tumors assessed by flow cytometry were diploid. Parenchymal hepatic metastases developed in only two patients. The overall 5-year survival rate was 36%, and matched cases did not vary significantly in survival from typical nonmucinous adenocarcinomas. There was a trend toward poorer survival for patients with advanced-stage tumor. Survival was not affected by primary site, ploidy, presence of vascular/lymphatic invasion or residual adenoma, or percentage of extracellular mucin or signet-ring cells. Our cases were somewhat lower stage than literature cases of signet-ring cell carcinoma of the lintis plastica variant.