Perforated rectosigmoid colon resulting from gastrointestinal stromal tumor presenting with peritonitis: A case report.

Introduction: Colorectal perforations can arise from various causes. The most common cause of the colorectal perforations is diverticulitis, while tumors account for only a small part. Perforations frequently occur in older patients, particularly in the sigmoid colon, and distinguishing between those caused by diverticulitis and colorectal cancer can be clinically challenging. Gastrointestinal stromal tumors (GISTs) account for a small percentage of gastrointestinal malignancies, and rectal perforation due to GISTs is rare but can lead to severe complications such as peritonitis.

Case Presentation: A 55-year-old male with a medical history of hypertension and urethral stones presented with left lower quadrant abdominal pain for two days. Abdomen computed tomography (CT) revealed perforation of rectosigmoid colon, leading to an anterior resection and loop ileostomy due to short transverse colon. Postoperative histological examination identified GIST through KIT (CD117) and DOG-1 staining. The tumor was staged as pT2N0M0 (stage I), and classified as high risk in NIH criteria.

Discussion: Differentiating between colorectal cancer perforation and diverticulitis is challenging, but CT findings like the absence of diverticula and shouldered edges help distinguish them. Sigmoid colon perforation due to GISTs is rare, often caused by tumor rupture. Early surgical resection with clear margins and adjuvant therapy like Imatinib improve survival rates. For colorectal perforations, immediate surgery is essential to prevent life-threatening complications like peritonitis and ensure optimal outcomes.

Conclusion: Accurate differentiation between malignancy-related colonic perforation and diverticulitis is vital. Early recognition, prompt surgery, and tailored treatment are key in managing perforated rectal GISTs.