Abstract
Lynch syndrome (LS) is a disorder caused by mismatch repair gene mutations, which have been recognized to be associated with an increased frequency of colorectal and extracolorectal tumors. However, it remains controversial as to whether total or segmental colectomy should be performed to treat colorectal cancer in patients with LS. A 58-year-old male underwent total colectomy with ileostomy for advanced transverse colon cancer. He was also found to have LS based on his characteristic family history and the findings of a preoperative examination, including a microsatellite instability analysis of past multiple metachronous cancers. The postoperative histological findings showed mucinous adenocarcinoma without lymph node metastasis, and the loss of the MSH2 protein expression was confirmed on an immunohistochemical examination. The present case provided important information on the clinical management of multiple developing metachronous colorectal cancers in patients with LS.