Perforated Ileocecal Adenocarcinoma Revealing Long-Standing Crohn's Disease: A Rare Cause of Generalized Peritonitis

Abstract

Introduction: Small bowel and ileocaecal adenocarcinomas are rare but recognised complications of long-standing Crohn's disease. Their diagnosis is challenging because symptoms frequently mimic inflammatory disease activity. Presentation with bowel perforation and generalised peritonitis is exceptional. Case Presentation: An 87-year-old overweight woman with a more than 30-year history of medically treated Crohn's disease presented with acute diffuse abdominal pain, vomiting, abdominal distension, and cessation of bowel transit. Clinical examination revealed generalised peritonitis associated with haemodynamic instability (heart rate 120 beats/min, blood pressure 90/60 mmHg). Laboratory investigations demonstrated leucocytosis (14,100/mm³), C-reactive protein of 449 mg/L, hyponatraemia (132 mmol/L), and severe hypokalaemia (2.66 mmol/L). Contrast-enhanced computed tomography demonstrated irregular heterogeneous thickening of the caecum associated with multiple intra-abdominal collections, pneumoperitoneum, mesenteric lymphadenopathy, diffuse ascites, peritoneal nodules suggestive of carcinomatosis, and suspicious bilobar liver lesions. Emergency laparotomy revealed generalised purulent peritonitis secondary to perforation of a thickened ileocaecal segment. Ileocaecal resection with double stoma formation was performed. Histopathological examination demonstrated a moderately differentiated adenocarcinoma with a 40% mucinous component infiltrating the entire bowel wall with perforation and visceral peritoneal invasion. Vascular emboli were present without perineural invasion. Six of twenty-one lymph nodes were metastatic, including four with extracapsular extension. The tumour was staged as pT4aN2Mx. The postoperative course was complicated by hydroelectrolytic disturbances that were successfully corrected. Intestinal continuity was restored later, and the patient remained free of clinical recurrence after six months. Conclusion: Advanced adenocarcinoma should be suspected in elderly patients with long-standing Crohn's disease presenting with acute abdominal complications. Histopathological examination remains essential for establishing the diagnosis and guiding postoperative management.