Primary diffuse malignant epithelioid peritoneal mesothelioma of the greater omentum in an asbestos-naive patient: a case report

Our plain-English summary of Primary diffuse malignant epithelioid peritoneal mesothelioma of the greater omentum in an asbestos-naive patient: a case report, by X. Gan, Y. Tuo, L. Huang, et al (Frontiers in Medicine, 2026).

The study

• Authors: X. Gan, Y. Tuo, L. Huang, Q. Yang, H. Liu
• Journal: Frontiers in Medicine
• Published: 2026;13:1808853
• Type of article: Case report
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant mesothelioma is a rare malignant neoplasm of mesothelial origin, with primary involvement of the greater omentum being exceptionally uncommon. Nonspecific clinical manifestations often lead to misdiagnosis, and cases without asbestos exposure further increase diagnostic complexity.

Case Presentation: A 71-year-old male without asbestos exposure was admitted for recurrent diarrhea (>1 year), abdominal distension (>10 days), and unintentional weight loss (5 kg in 3 months). Physical examination revealed a 20-cm firm abdominal mass, and abdominal contrast-enhanced CT showed omental-peritoneal "cake-like" thickening with massive peritoneal effusion. Laparoscopic palliative tumor resection and peritoneal effusion drainage were performed, and postoperative pathology/immunohistochemistry (CK+, CR+, CK5/6+, D2-40+, WT1+, CD20-, CDX2-) confirmed epithelioid mesothelioma of the omentum. Postoperative management included anti-infective therapy, nutritional support, and Cinobufacini Capsule-based anti-tumor treatment, with stable disease control at 3-month follow-up.

Conclusion: Definitive diagnosis of primary greater omental malignant mesothelioma relies on pathology and immunohistochemistry. For unresectable cases, palliative surgery combined with individualized adjuvant therapy may achieve favorable short-term outcomes, highlighting the need for early clinical suspicion in patients with unexplained abdominal symptoms.

Copyright © 2026 Gan, Tuo, Huang, Yang and Liu.

In plain English

This case report described a 71-year-old man admitted to Dazhou Central Hospital, China, in November 2025 with over a year of recurrent diarrhea, about 10 days of worsening abdominal distension, and a 5 kg weight loss over three months. The authors reported that a review of his occupational and environmental history found no asbestos contact. He had a 40-pack-year smoking history. CT showed cake-like thickening of the greater omentum, peritoneum and mesentery, with a large volume of abdominal fluid. At laparoscopic surgery about 2,500 ml of fluid was drained. A frozen section favored adenocarcinoma, and palliative tumor removal was performed. Final pathology and immunohistochemistry confirmed epithelioid mesothelioma of the omentum. Tuberculous peritonitis was considered because of a positive T-SPOT test but was ruled out. He received anti-infective and nutritional treatment and Cinobufacini Capsules. Three months after discharge he had no diarrhea, distension, palpable mass or returning fluid. The authors concluded that mesothelioma should be considered for omental masses even without asbestos exposure. They stated that three months of follow-up cannot assess long-term outcomes. Parts of the discussion contradict the case description.

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 71-year-old man admitted to Dazhou Central Hospital, Dazhou, China, on November 10, 2025, with recurrent diarrhea and abdominal distension
• Exposure: No asbestos exposure, based on a review of the patient's occupational and environmental history; no fiber type is named. He had a 40-pack-year smoking history and had quit 1 year before.
• Main results:
  • Final pathology of the resected specimen confirmed epithelioid mesothelioma of the omentum
  • Immunohistochemistry was positive for CK, Vim, CK7, CR (calretinin), CK5/6, D2-40 and WT1, and negative for CK20, CDX2, Hepa, PAX-8 and NKX3.1
  • The Ki-67 proliferation index was approximately 10%
  • The intraoperative frozen section initially favored adenocarcinoma, which led to palliative tumor resection and drainage of ascites
  • About 2,500 ml of ascitic fluid was drained during surgery
  • Tuberculous peritonitis was considered because of a positive T-SPOT result, and was then ruled out
  • At the March 4, 2026 assessment (three months after discharge), the patient had no recurrence of diarrhea or abdominal distension and no abdominal mass on examination
  • At follow-up, ultrasound showed no re-accumulation of ascites
• The authors' conclusion: The authors concluded that mesothelioma should be considered in the differential diagnosis of omental masses even when there is no asbestos exposure, and that a structured diagnostic framework is needed
• Limitations the authors state:
  • Follow-up was only three months, so long-term survival or recurrence cannot be assessed
  • The patient did not receive standardized systemic therapy under a clinical trial protocol, and no objective tumor response assessment was done
  • Because of limited tissue, the markers BAP1 and MTAP were not tested
  • As a single case, the findings may not apply to all patients with peritoneal mesothelioma

Topics

Medical terms in this study, explained in our Lexicon: Epithelioid, Peritoneal Mesothelioma, Omentum, Mesothelioma, Neoplasm, Misdiagnosis, Asbestos Exposure, Palliative Care.

Related studies

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• Primary Peritoneal Mesothelioma Affecting the Greater Omentum That Mimicked an Omental Infarction: A Case Report — J.C. Cravero, T. Yakubik, et al. (2024)
• Multiple malignant epithelioid mesotheliomas of the liver and greater omentum: a case report and review of the literature — K. Minami, H. Okumura, et al. (2017)
• Primary malignant mesothelioma of the greater omentum: report of a case — Y.C. Liu, Y.L. Kuo, et al. (2004)
• Gray scale sonographic presentation of a mesothelioma of the greater omentum — J.M. Shah, D.L. King (1979)
• Benign Cystic Mesothelioma of the Peritoneum Arising at the Greater Omentum in a 14-Year-Old Boy — Y. Hirayama, N. Higashidate, et al. (2025)

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