Benign Diverticulitis and Fat Saponification Mimicking Peritoneal Carcinomatosis and Colonic Malignancy
A 59-year-old man presenting with a large bowel obstruction was found to have a rare instance of “double mimicry,” where severe chronic diverticulitis and post-pancreatitis fat necrosis simultaneously simulated a metastatic colonic cancer, Cureus reported.
- A 59-year-old man presented with large bowel obstruction, acute abdominal pain, and obstipation.
- Emergency laparotomy revealed a sigmoid mass and widespread peritoneal nodules that macroscopically resembled metastatic carcinomatosis.
- Final histopathology confirmed benign chronic diverticulitis and fat saponification from prior necrotizing pancreatitis, with no evidence of malignancy.
Distinguishing non-neoplastic processes from true neoplastic dissemination is difficult and requires multidisciplinary evaluation.
This causes fat necrosis, saponification, and subsequent calcification within the peritoneal cavity, mesentery, and omentum. At surgical exploration or on cross-sectional imaging, these solid necrotic nodules can masquerade as metastatic peritoneal deposits, a rare entity described in the surgical literature as a surgical trompe l’oeil.
Four months prior to his acute presentation, the patient had been admitted to the Intensive Care Unit with severe acute necrotizing pancreatitis of biliary etiology. Urgent sigmoidoscopy revealed a luminal stricture approximately 30 cm from the anal verge with irregular, nodular, and highly friable mucosa.
Given the obstructive presentation and the strong suspicion of an occlusive sigmoid tumor, the patient underwent an emergency laparotomy. Exploration revealed a hard, neoplasm-like mass in the sigmoid colon alongside widespread, solid, whitish nodules scattered across the left paracolic gutter, the ileocecal region, the greater omentum, and the transverse mesocolon.
Because intraoperative frozen section analysis was not available in this out-of-hours emergency setting, a diverting loop transverse colostomy was performed to relieve the obstruction.
Endoscopic biopsies showed fragments of granulation tissue with exuberant polymorphic inflammatory infiltrate and no evidence of neoplasia.
Following multidisciplinary discussion favoring a benign etiology, the patient underwent elective laparoscopic sigmoidectomy two months after the index operation. Final pathology confirmed severe chronic diverticulitis with prominent reactive fibroblastic proliferation and no neoplastic cells. The patient recovered uneventfully and later underwent elective laparoscopic cholecystectomy and colostomy closure, remaining well at three months of follow-up.
Disclaimer: The information provided in this article is for educational and scientific communication purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider regarding any medical condition, diagnosis, or treatment plan.