A Case of Primary Malignant Peritoneal Mesothelioma

Our plain-English summary of A Case of Primary Malignant Peritoneal Mesothelioma, by L. Betancourt, J. Wallace, E. Sugarman, et al (Curēus, 2025).

The study

• Authors: L. Betancourt, J. Wallace, E. Sugarman, B. Estevez, N. La Roz, E. Castillo, R. Torres, D. Casadesus
• Journal: Curēus
• Published: 2025;17(10):e93864
• Type of article: Case report
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Primary malignant mesothelioma (MPM) is a rare malignancy that arises from the epithelial cells that line visceral cavities. The primary pleural presentation is known as the most commonly seen presentation and is best recognized clinically. Less commonly, mesothelioma can arise from epithelial cells lining other visceral cavities, including the peritoneum and pericardium. Primary peritoneal presentations are often difficult to diagnose due to vague symptoms such as abdominal distention, anorexia, and diffuse pain. These symptoms overlap with those of many more common gastrointestinal conditions, often leading to delayed diagnosis. We report a male in his 40s with a past medical history of hypertension and diabetes mellitus type 2 who presented to the emergency room with non-specific abdominal complaints. He had a history of longstanding work on demolition sites. Treatment was initiated following studies that tested positive for H. pylori infection. A CT scan of the abdomen revealed nodular fat stranding of the omentum, with several confluent peritoneal nodules and small-volume ascites. An omental biopsy showed tumor cells positive for markers indicative of epithelioid-type malignant mesothelioma, with the peritoneum identified as the primary site. A key piece of this patient's case was long-standing exposure to demolition sites and asbestos. Asbestos exposure is a well-documented risk factor for the development of mesothelioma. This history was obtained but did not aid in guiding diagnostic practices due to overlapping symptomatology. The discovery of an H. pylori infection may have delayed the diagnosis of primary malignant peritoneal mesothelioma (PMPM) and its appropriate treatment, as H. pylori is a much more common condition.

Copyright © 2025, Betancourt et al.

In plain English

This article is a case report about one patient: a Hispanic man in his 40s with high blood pressure and type 2 diabetes. He went to an emergency department after six weeks of worsening abdominal discomfort and swelling, with nausea, constipation and feeling full early. He reported long-standing work exposure to debris from demolishing old buildings, without a respirator. The authors describe this as long-term occupational asbestos exposure; no fiber type was named. An endoscopy found active H. pylori stomach inflammation, which was treated with antibiotics. A CT scan showed nodules on the abdominal lining (peritoneum) and a small amount of fluid. A biopsy led to a diagnosis of epithelioid malignant mesothelioma, with the peritoneum as the primary site. His tumor-burden score (Peritoneal Cancer Index) was 18. He received chemotherapy and then maintenance treatment. The disease progressed, and he started immunotherapy. The authors wrote that his symptoms overlapped with the stomach and colon findings, and that this initially diverted the work-up. They concluded that this cancer should be considered in patients with unexplained abdominal fluid and peritoneal nodules, particularly those with a history of asbestos exposure.

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 (one patient)
• Who was studied: One Hispanic man in his 40s with hypertension and type 2 diabetes who came to an emergency department (author affiliations in Miami, USA) after six weeks of abdominal discomfort and distension
• Exposure: Long-standing work exposure to debris from demolition of old buildings, without a respirator. The authors call this long-term occupational asbestos exposure. No fiber type, duration in years or dose is given.
• Main results:
  • The tumor marker CA-125 was elevated at 98 U/mL (reference less than 35 U/mL).
  • Upper endoscopy showed a small necrotic ulcer consistent with active H. pylori gastritis, which was treated with antibiotics.
  • Colonoscopy found an 8 mm adenomatous polyp in the sigmoid colon that was negative for malignancy.
  • CT showed peritoneal nodules, the largest measuring 1.4 cm (left lower quadrant) and 1.8 cm (pelvis). It showed no pleural nodularity.
  • Omental biopsy supported a diagnosis of epithelioid-type malignant mesothelioma with the peritoneum as the primary site.
  • PET scan showed increased uptake in the omentum and peritoneum, with SUVs from 4.5 to 6.3.
  • The patient's Peritoneal Cancer Index was 18, which the authors described as moderate tumor burden.
  • After first-line cisplatin and pemetrexed followed by bevacizumab maintenance, imaging after two months on maintenance showed disease progression. Ipilimumab and nivolumab were then started.
  • The authors reported that the patient's symptoms overlapped with the gastritis and colonic polyp findings, which initially diverted the work-up.
• The authors' conclusion: The authors concluded that primary malignant peritoneal mesothelioma should be considered in patients with unexplained ascites and peritoneal nodularity, particularly those with a history of asbestos exposure. They also concluded that occupational history, early imaging and prompt biopsy are critical for timely diagnosis.

Topics

Medical terms in this study, explained in our Lexicon: Peritoneal Mesothelioma, Mesothelioma, Peritoneum, Pericardium, CT Scan, Omentum, Ascites, Biopsy.

Related studies

• From the archives of the AFIP: primary peritoneal tumors: imaging features with pathologic correlation — A.D. Levy, J. Arnáiz, et al. (2008)
• Treatment of primary peritoneal mesothelioma by continuous hyperthermic peritoneal perfusion (CHPP) — B.J. Park, H.R. Alexander, et al. (1999)
• Primary malignant peritoneal mesothelioma. A report of seven cases and a review of the literature — J.A. Asensio, P. Goldblatt, et al. (1990)
• The Pathologic Peritoneal Cancer Index (PCI) Strongly Differs From the Surgical PCI in Peritoneal Metastases Arising From Various Primary Tumors — A. Bhatt, Y. Yonemura, et al. (2020)
• Peritoneal malignant mesothelioma (PMM), and primary peritoneal serous carcinoma (PPSC) and reactive mesothelial hyperplasia (RMH) of the peritoneum. Immunohistochemical and fluorescence in situ hybridisation (FISH) analyses — T. Kawai, S. Tominaga, et al. (2016)
• Incidence, Survival Analysis and Future Perspective of Primary Peritoneal Mesothelioma (PPM): A Population-Based Study from SEER Database — A. Ullah, A. Waheed, et al. (2022)

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