Peritoneal Mesothelioma in a Patient with Long-Standing Crohn's Disease: Cause or Coincidence?

Introduction: Peritoneal mesothelioma (PeM) is a rare cancer of the peritoneal lining. Unlike pleural mesothelioma, PeM is less frequently linked to asbestos exposure. Chronic serosal inflammation, as seen in Crohn's disease (CD), has been proposed as a contributing factor in its carcinogenesis. Case Presentation: A male with a long-standing history of ileal CD presented with recurrent episodes of intestinal subocclusion. Imaging showed complex active ileal CD, new-onset ascites, and peritoneal densification. Intraoperatively, a small bowel mass adherent to the sigmoid colon and millimetric nodules of the peritoneum were identified. Histology of the resected segment showed CD-related changes and multiple areas of epithelioid mesothelioma, despite no asbestos exposure. He received cytoreductive surgery and hyperthermic intraperitoneal chemotherapy, with no signs of recurrence after 15 months. Discussion/Conclusion: We present a rare case of non-asbestos-related PeM in a patient with long-standing active CD, highlighting the diagnostic challenges and possible link between chronic serosal inflammation and PeM.