Radiologically suspected locally recurrent rectal cancer presenting with rectal perforation and rectocutaneous fistula years after multimodal therapy: a case report

Introduction Local recurrence of rectal cancer after multimodal therapy may be difficult to distinguish from post-radiation changes and can lead to severe complications if diagnosis is delayed. Case description We report the case of a 62-year-old woman with previously treated rectal adenocarcinoma who developed Positron emission tomography (PET)/Computed tomography (CT) findings suspicious for local recurrence despite benign colonoscopic biopsy showing post-radiation changes. Subsequent imaging demonstrated disease progression, and the patient presented with rectal perforation and a rectocutaneous fistula requiring urgent diverting colostomy, drainage, and antibiotic therapy. She improved clinically following multidisciplinary management. Discussion This case highlights the diagnostic challenges of differentiating recurrent rectal cancer from post-radiation changes and underscores the importance of serial imaging and multidisciplinary evaluation when clinical suspicion persists despite negative biopsy findings.