Suspicious T1 colon cancer with synchronous liver metastasis not detected by preoperative imaging study

Colorectal carcinoma invading the submucosa but not the muscularis propria (pT1) represents the earliest form of clinically relevant colorectal cancer in most patients. T1 colorectal cancer with synchronous liver metastasis is considered to be rare. We report a rare case of T1 colon cancer with synchronous liver metastasis not detected by preoperative imaging study. A 54-year-old male patient presented to our department for treatment of sigmoid colon cancer following an endoscopic submucosal dissection. Histopathological examination revealed the pedunculated mass was moderately differentiated adenocarcinoma without lymphovascular invasion and the depth of submucosal invasion was 2,000 μm, the resection margin was not involved. We performed a laparoscopic anterior resection with lymph node dissection. After the 3 months, the patient’s carcinoembryonic antigen level elevated from 1.4 to 7.26 ng/mL (normal level: