Atypical abdominal pain: uncovering malignant peritoneal mesothelioma in suspected Crohn's disease: a case report

Our plain-English summary of Atypical abdominal pain: uncovering malignant peritoneal mesothelioma in suspected Crohn's disease: a case report, by C. Loehr, L. Boudreaux, A.P. Uhlhorn, et al (Journal of Gastrointestinal Oncology, 2025).

The study

• Authors: C. Loehr, L. Boudreaux, A.P. Uhlhorn, N. Loganantharaj
• Journal: Journal of Gastrointestinal Oncology
• Published: 2025;16(5):2485-2491
• Type of article: Case report
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant peritoneal mesothelioma (MPM) is a rare and aggressive cancer from the serosal membranes of the abdominal cavity. In the United States, MPM accounts for about 10-15% of all mesothelioma cases, and translates into approximately 600 new cases diagnosed annually. It is typically diagnosed in Caucasian individuals, and while asbestos exposure is a well-established risk factor for pleural mesothelioma, its association with peritoneal mesothelioma remains less clear. Clinical symptoms of MPM, such as abdominal pain, bloating, and weight loss, overlap with other gastrointestinal disorders, which often leads to delayed diagnosis. This case report presents a unique instance of MPM initially misdiagnosed as ileal Crohn's disease (CD), highlighting the importance of differential diagnosis in such complex cases.

Case Description: A 62-year-old Caucasian male with a history of diverticulitis was referred to an inflammatory bowel disease (IBD) center for reported ileal CD. The patient experienced 3 years of persistent abdominal pain, constipation, fatigue, early satiety, and weight loss. Previous imaging, including computed tomography scans, suggested ileal thickening and inflammatory fat stranding, but no histologic confirmation of CD was obtained. He had been treated with Humira without improvement, and intermittent courses of prednisone provided temporary relief. Despite his diagnosis of CD, his symptoms were unresponsive to standard treatments. Upon further evaluation, Humira levels were undetectable, and magnetic resonance enterography (MRE) yielded no significant findings. A diagnostic laparoscopy was performed, revealing peritoneal mesothelioma, which was confirmed by biopsy as the diffuse, epithelioid type. The diagnosis was supported by positive immunohistochemical staining for calretinin, CK7, and CK5/6.

Conclusions: This case underscores the importance of considering a broad differential diagnosis in patients with non-specific abdominal symptoms. Although CD was initially suspected, MPM was ultimately identified through diagnostic laparoscopy and histological analysis. The case highlights the need for comprehensive diagnostic evaluation, including histologic confirmation and objective markers, to accurately differentiate between conditions with similar presentations. Clinicians should maintain a high index of suspicion for rare etiologies, such as peritoneal mesothelioma, particularly in patients with a history of asbestos exposure, to ensure timely and appropriate management.

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In plain English

This case report described one patient: a 62-year-old Caucasian man referred to an academic inflammatory bowel disease center with a diagnosis of ileal Crohn's disease. He had had constant abdominal pain with constipation for 3 years, along with fatigue, early satiety and weight loss. He reported asbestos exposure for approximately 40 years working as a radio technician, but had no evidence of bilateral pleural plaques or fibrosis. His Crohn's diagnosis had never been confirmed by tissue examination. Prednisone relieved his pain. Adalimumab (Humira) did not, and his drug level was undetectable. Diagnostic laparoscopy found peritoneal mesothelioma, confirmed by biopsy as the diffuse, epithelioid type. A repeat laparoscopy showed widespread disease in the abdomen, and he was judged not to be a surgical candidate. He entered a chemotherapy and immunotherapy trial; his outcome was not reported. Because no disease-causing inherited gene variants were found, the authors suspected a spontaneous mesothelioma. The authors concluded that other causes should be considered when symptoms are non-specific. They noted that a single case report has limited generalizability.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report (single patient)
• Who was studied: One 62-year-old Caucasian man with a history of diverticulitis, referred for reported ileal Crohn's disease and evaluated at University Medical Center New Orleans, USA. Symptoms began in 2021, and mesothelioma was diagnosed in July 2024.
• Exposure: Patient-reported asbestos exposure for approximately 40 years while working as a radio technician. No fiber type was stated. He had no evidence of bilateral pleural plaques or fibrosis.
• Main results:
  • The patient had constant stabbing abdominal pain for 3 years, with constipation.
  • The Crohn's disease diagnosis was never confirmed by histology.
  • His abdominal pain resolved immediately with prednisone.
  • His symptoms did not improve on Humira. When checked, his Humira level was undetectable, with moderate antibodies.
  • Diagnostic laparoscopy revealed peritoneal mesothelioma, confirmed by biopsy as the diffuse, epithelioid type. Staining was positive for calretinin, pan-keratin, CK7 and CK5/6.
  • CT of the chest showed no evidence of thoracic metastatic disease.
  • A repeat laparoscopy a week later showed diffuse intraperitoneal disease involving most of the small bowel and small bowel mesentery. The patient was deemed a nonsurgical candidate.
  • He was enrolled in a phase 2 trial and randomized to carboplatin, pemetrexed, bevacizumab and atezolizumab. No treatment outcome was reported.
  • The authors suspected a spontaneous mesothelioma because no pathogenic germline variants were found.
• The authors' conclusion: The authors concluded that other causes should be considered when symptoms are non-specific, to ensure appropriate diagnosis and treatment. They described the case as a rare, atypical presentation of peritoneal mesothelioma in the setting of asbestos exposure.
• Limitations the authors state:
  • As a single case report, it has limited generalizability.

Topics

Medical terms in this study, explained in our Lexicon: Peritoneal Mesothelioma, Mesothelioma, Asbestos Exposure, Pleural Mesothelioma, Differential Diagnosis, Early Satiety, Diagnostic Laparoscopy, Biopsy.

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