A Case of Metachronous Ascending Colon Metastasis from Gastric Cancer That Was Difficult to Diagnose

: A 60s man with a history of laparoscopic distal gastrectomy(LDG)of gastric cancer in January 2015was followed up in an outpatient clinic. He remained healthy without recurrence for about 2 years, but in February 2017, colonoscopy identified an elevated lesion that covered one-third of the circumference in the ascending colon. Biopsy revealed that this lesion had poorly differentiated adenocarcinoma. No other metastatic lesions were noted on thoraco-abdominal CT, and tumor markers were not elevated in a blood test. Right hemicolectomy with D3 nodal dissection was performed on March 2017. Although regional lymph node metastasis was noted during surgery, distant metastasis was not identified. Histological examination revealed that the ascending colon tumor had poorly differentiated adenocarcinoma very similar to that of the primary gastric cancer, and the lesion was diagnosed as metastasis from previous gastric carcinoma. Pathological findings showed pPM0, pDM0, pRM0, pCY0, and definitive surgical treatment was confirmed. However, 2 months after the surgery, ascites caused by peritoneal and bilateral supraclavicular lymph node metastases were detected on CT. He passed away 6months after the last surgery. We report a case of metachronous ascending colon metastasis from gastric cancer that was difficult to preoperatively diagnose.