One patient with synchronous multiple primary colon cancers which is easy to miss: a case report.

BACKGROUND: Multiple primary colon cancer is a relatively rare type of colon cancer (CC), and it is even rarer to have endoscopic obstruction. CASE SUMMARY: A 70-year-old female patient was previously diagnosed with sigmoid colon cancer accompanied by endoscopic obstruction at an external hospital. Preoperative abdominal enhanced CT in our hospital revealed one segmental bowel wall thickening with intussusception, and two separate thickened lesions in the transverse colon. During the operation, it was found that the intestinal wall of sigmoid colon, the transverse colon near splenic flexure and the ascending colon were obviously thickened and stiff, and the lymph nodes at the root of inferior mesenteric artery, the ileocolic artery and middle colon artery were swollen. Finally, we performed laparoscopic sigmoidectomy, left hemicolectomy, and right hemicolectomy with mesenteric lymph node dissection and ileorectal anastomosis. Postoperative pathological examination confirmed that adenocarcinoma existed in sigmoid colon, transverse colon and ascending colon. CONCLUSION: Intraoperative comprehensive exploration is critical for the management of obstructive colon cancer. For patients with incomplete preoperative colonoscopy caused by tumor-induced luminal obstruction, meticulous intraoperative assessment is essential to avoid missed diagnosis of synchronous multiple CC and optimize long-term oncological outcomes.