Rectal adenocarcinoma resection specimen with an incidental carcinoid in the resection margin

Three cases of incidental carcinoid tumors have been identified in the surgical margin of rectal adenocarcinoma resection specimens. In all cases the rectal carcinoids exhibited low-risk features, such as a tumor size <10 mm, no muscularis propria invasion and no lymph node involvement. No further excision was conducted and the three cases were followed up for 38, 26 and 14 months, respectively. No regional or distant rectal carcinoid recurrence was identified. Occasionally this is inevitable in order to achieve a positive resection margin for the microcarcinoid during the surgical treatment of another malignancy. However, such carcinoids are usually low-risk and behave less aggressively than same-site adenocarcinomas. Thus, it appears reasonable to avoid further excision in patients who are undergoing a rectal adenocarcinoma resection that exhibits a positive margin for low-risk carcinoid tumor.