Case Report: Diagnostic and therapeutic reflections on one case of greater omental adhesion misdiagnosed as peritoneal metastasis following rectal cancer surgery

Objective To investigate the differential diagnostic criteria and decision-making logic for distinguishing benign intra-abdominal adhesions from peritoneal metastasis following preoperative radiotherapy and surgical resection for rectal cancer, thereby providing clinical reference for managing similar atypical peritoneal lesions. Methods We conducted a retrospective analysis of clinical data from a 57-year-old patient with stage pT4bN1cM0 rectal cancer who received postoperative radiotherapy at our institution. The patient was initially suspected of having peritoneal metastasis based on an abnormally enhanced nodular lesion in the right lower anterior abdominal wall. We systematically reviewed the diagnostic and therapeutic process, multidisciplinary team (MDT) decision-making, and pathological diagnosis, and analyzed the causes of misdiagnosis, differential diagnostic key points, and management strategies in conjunction with relevant literature. Results The patient underwent laparoscopic exploration combined with abdominal wall lesion resection. Postoperative pathology confirmed greater omental adhesion with localized inflammatory reaction, effectively excluding malignant metastasis. Conclusions Cross-sectional imaging has inherent limitations in the diagnosis of peritoneal lesions. For patients with suspected peritoneal lesions following rectal cancer surgery, comprehensive evaluation should integrate trauma history, tumor markers, clinical symptoms, and imaging characteristics. The patient had no evidence of extraperitoneal metastasis throughout the diagnosis and treatment, and the interval between the initial radical rectal cancer surgery and the detection of suspected peritoneal metastatic lesions was 2 years. Individualized diagnostic and therapeutic decisions guided by MDT, with appropriate application of laparoscopic minimally invasive exploration, can effectively improve diagnostic accuracy and avoid overtreatment or diagnostic delays.