Pseudo-Meigs'syndrome mimicking malignant pleural mesothelioma: a case report and diagnostic pitfall analysis

Our plain-English summary of Pseudo-Meigs'syndrome mimicking malignant pleural mesothelioma: a case report and diagnostic pitfall analysis, by H. Sheng, W. Zong, Z. Song, et al (Frontiers in Medicine, 2026).

The study

• Authors: H. Sheng, W. Zong, Z. Song, Q. Yu
• Journal: Frontiers in Medicine
• Published: 2026;13:1849707
• Type of article: Case report
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: To investigate the clinical characteristics, misdiagnosis causes, and preventive strategies of pseudo-Meigs' syndrome, and to improve clinicians' awareness of pelvic tumors presenting with pleural effusion and ascites.

Methods: A 45-year-old woman presented with a 2-month history of dyspnea and a large right-sided pleural effusion with markedly elevated CYFRA 21-1 (>500 ng/mL). Thoracoscopic pleural biopsy showed atypical cells with positive Calretinin, leading to a pathology report of "suspicious for mesothelioma." The patient was diagnosed with malignant pleural mesothelioma and received two cycles of pemetrexed plus carboplatin chemotherapy. When symptoms did not improve and ascites developed, pelvic CT revealed a 7.0 × 5.5 cm ovarian mass.

Results: Postoperative pathology confirmed bilateral ovarian borderline serous cystadenoma with focal low-grade serous carcinoma-pseudo-Meigs' syndrome. After tumor resection, the pleural effusion and ascites resolved completely, and the patient remained disease-free at 4-year follow-up.

Conclusion: Pseudo-Meigs' syndrome can closely mimic malignant pleural mesothelioma. For any woman with unexplained pleural effusion, pelvic imaging should be performed before invasive thoracic procedures to avoid catastrophic misdiagnosis.

Copyright © 2026 Sheng, Zong, Song and Yu.

In plain English

This case report described one 45-year-old woman seen at Tianjin Chest Hospital in China in May 2021. She had been short of breath for 2 months and had a large fluid collection around the right lung (pleural effusion). She had no history of smoking or occupational asbestos exposure. A tumor marker, CYFRA 21-1, measured above 500 ng/mL in her pleural fluid. A biopsy of the chest lining was reported as "suspicious for mesothelioma." She was diagnosed with malignant pleural mesothelioma and given two cycles of pemetrexed plus carboplatin chemotherapy. Her breathing did not improve, and fluid built up in her abdomen (ascites). Pelvic CT then showed masses in the uterus and both adnexal regions. Surgery found bilateral ovarian borderline serous cystadenoma with focal low-grade serous carcinoma, a picture the authors called pseudo-Meigs' syndrome. After the tumor was removed, the chest and abdominal fluid cleared without further treatment, and she had no evidence of recurrence through November 2025. The authors concluded that pseudo-Meigs' syndrome can mimic malignant pleural mesothelioma and that pelvic imaging should be mandatory in any woman with unexplained pleural effusion.

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: Retrospective case report of a single patient
• Who was studied: One 45-year-old woman seen in the respiratory department of Tianjin Chest Hospital, Tianjin, China, from May 20, 2021, with follow-up to November 2025
• Exposure: No asbestos exposure was studied. The patient reported no history of smoking or occupational asbestos exposure.
• Main results:
  • In this patient, CYFRA 21-1 in the pleural fluid was above 500 ng/mL. Serum CYFRA 21-1 was 9.11 ng/mL (normal below 3.3 ng/mL), and serum CA-125 was initially normal.
  • The parietal pleural biopsy showed scattered cords of atypical cells. Staining was positive for Calretinin, CK(P), WT-1 and Vimentin, and Ki-67 was above 10%. The report concluded "suspicious for mesothelioma."
  • Based on that report, the patient was diagnosed with malignant pleural mesothelioma. She received two cycles of pemetrexed (0.8 g) plus carboplatin (0.4 g) on June 1 and June 24, 2021.
  • After chemotherapy her shortness of breath did not improve and she developed moderate ascites. Pelvic CT showed masses in the uterus and both adnexal regions. Repeat serum CA-125 was 696.80 U/mL.
  • Surgical pathology showed bilateral ovarian borderline serous cystadenoma with focal areas transforming into low-grade serous carcinoma, with endometriosis and psammoma bodies. Surgical margins were negative.
  • After the tumor was removed, the pleural effusion and ascites resolved completely without further intervention. A chest CT on December 21, 2021 confirmed this.
  • At what the authors called 4-year follow-up (December 2021 to November 2025), the patient was asymptomatic with no evidence of recurrence.
• The authors' conclusion: The authors concluded that pseudo-Meigs' syndrome can closely mimic malignant pleural mesothelioma, and that in this case the error led to unnecessary chemotherapy. They drew three lessons: pelvic imaging should be mandatory in any woman with unexplained pleural effusion; telling reactive mesothelial hyperplasia apart from mesothelioma on biopsy can be challenging and requires caution; and elevated CYFRA 21-1 is not specific for malignancy.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Misdiagnosis, Pleural Effusion, Ascites, Dyspnea, Pleural Biopsy, Calretinin, Pathology Report.

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