Abstract
Small bowel perforation due to hematogenous metastatic tumor emboli is a rare event, especially in a patient with rectal cancer. We report a 75-year-old man with relapsed rectal cancer who developed an acute abdomen, which was found to be due to a perforated terminal ileum. Emergency surgery involved segmental resection and ileostomy. The pathology of the resected small bowel showed multifocal and extensive metastatic tumor emboli in the entire wall, leading to transmural infarction followed by perforation, without a discrete tumor mass. The pathology with immunohistochemistry showed a rectal tumor that was positive for CK-20 but negative for CK-7 and TTF-1. This extremely rare complication of rectal cancer resulted from ischemia and infarct caused by disseminated metastatic tumor emboli without direct invasion or mass formation.