Isolated primary pericardial sarcomatoid mesothelioma: a case report

Our plain-English summary of Isolated primary pericardial sarcomatoid mesothelioma: a case report, by P. Nezafati, R. Vilain, T. Singh (Frontiers in Oncology, 2026).

The study

• Authors: P. Nezafati, R. Vilain, T. Singh
• Journal: Frontiers in Oncology
• Published: 2026;16:1817459
• Type of article: Case report
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Primary pericardial mesothelioma is an exceedingly rare malignancy, often diagnosed late due to nonspecific clinical and radiologic findings. We report a case of isolated pericardial mesothelioma progressing from mesothelioma in situ to invasive sarcomatoid disease, presenting with recurrent effusions and constrictive pericarditis.

Case Presentation: A 58-year-old male with a remote history of Hodgkin's lymphoma (previously treated with chemotherapy and mediastinal radiotherapy) presented with progressive dyspnoea, orthopnoea, and recurrent pericardial and left pleural effusions. Initial diagnostic video-assisted thoracoscopic surgery (VATS) with mini-thoracotomy revealed densely adherent pericardium, intra-pericardial clots, and 1.5L of blood-stained pleural fluid. Histology demonstrated a sparse population of surfcatypical mesothelial proliferation with methylthioadenosine phosphorylase (MTAP) loss and retained BRCA1-associated protein 1 (BAP1). There was no invasive growth and therefore, the appearance for concerning for mesothelioma in situ, at a minimum. Cytology of the pleural fluid was non-malignant. Due to progressive constrictive physiology, a total pericardiectomy via median sternotomy was performed with femoro-femoral cardiopulmonary bypass. Intraoperatively, the pericardium was excised in the standard fashion for total pericardiectomy, and cardiopulmonary bypass was required due to dense epicardial adhesions. Final histopathology confirmed sarcomatoid mesothelioma with high-grade spindle cell morphology, brisk mitotic activity, necrosis, and MTAP loss. Immunohistochemistry was positive for WT1, calretinin, CK5/6, and D2-40. The patient was referred for oncology follow-up and underwent PET-CT staging for systemic therapy planning.

Conclusion: This case highlights the importance of early diagnostic suspicion in patients with prior mediastinal irradiation who present with recurrent pericardial effusions or evolving constrictive physiology. While pericardiectomy remains the standard of care for constriction regardless of etiology, the diagnosis of mesothelioma-particularly sarcomatoid subtype-warrants timely intervention. Early recognition of pre-invasive histological changes may offer a critical opportunity for curative resection before progression to aggressive disease.

Copyright © 2026 Nezafati, Vilain and Singh.

In plain English

This case report, by authors from John Hunter Hospital in Newcastle, Australia, described one 58-year-old man with a sarcomatoid mesothelioma confined to the pericardium, the sac around the heart. More than 20 years earlier he had been treated for Hodgkin lymphoma with chemotherapy and radiotherapy to the central chest (mediastinum). The article states he had no asbestos or other occupational exposure. He developed breathlessness, weight loss, and repeated fluid around the heart and left lung. Tests showed signs that the pericardium was constricting the heart. Fluid drawn from around the heart was negative for cancer. A first biopsy showed changes consistent with mesothelioma in situ, an early non-invasive form, with loss of the marker MTAP. After he worsened, the whole pericardium was removed using heart-lung bypass. That tissue showed invasive sarcomatoid mesothelioma. Recovery after surgery was uneventful, and he was referred for cancer staging. No later outcome was reported. The authors concluded that the tumor appearing more than two decades after radiotherapy raises the possibility that radiation contributed, but that a definitive causal relationship cannot be established.

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 58-year-old man, reported by authors from John Hunter Hospital, Newcastle, NSW, Australia
• Exposure: Prior chemotherapy and mediastinal radiotherapy for Hodgkin lymphoma more than 20 years earlier; the article reports no asbestos or other occupational exposure
• Main results:
  • The patient had no reported asbestos or other occupational exposure
  • Repeated drainage of fluid from around the heart yielded bloody, exudative fluid that was negative for cancer
  • At the first operation, 1.5 L of bloody fluid was drained from around the lung, and the pericardium was thickened, nodular and densely stuck down
  • The first biopsies showed changes consistent with mesothelioma in situ: sparse atypical mesothelial cells with MTAP loss and retained BAP1
  • The fully removed pericardium showed invasive sarcomatoid mesothelioma, with strong calretinin and WT1 staining and persistent MTAP loss
  • Recovery after total pericardiectomy was uneventful, and the patient was referred for oncology evaluation and PET-CT staging
• The authors' conclusion: The authors concluded that the development of sarcomatoid pericardial mesothelioma more than two decades after mediastinal radiotherapy raises the possibility that radiation contributed, but that a definitive causal relationship cannot be established
• Limitations the authors state:
  • The authors state that a definitive causal link between the prior radiation and the tumor cannot be established

Topics

Medical terms in this study, explained in our Lexicon: Pericardial, Sarcomatoid, Mesothelioma, Pericardial Mesothelioma, Mesothelioma in Situ, Chemotherapy, Pleural Effusion, Video-Assisted Thoracoscopic Surgery (VATS).

Related studies

• Primary sarcomatoid malignant pericardial mesothelioma — D. Jiang, M. Kong, et al. (2013)
• Primary malignant pericardial sarcomatoid mesothelioma: An autopsy report — H. Muta, Y. Sugita, et al. (2017)
• Sarcomatoid Type Primary Pericardial Mesothelioma with a Long-term Survival after the Onset of Cardiac Tamponade — C. Saisho, H. Ishii, et al. (2016)
• Primary malignant sarcomatoid mesothelioma in the pericardium — K. Tateishi, M. Ikeda, et al. (2013)
• Primary sarcomatoid malignant mesothelioma of the pericardium — T. Terada (2012)
• Primary Sarcomatoid Malignant Mesothelioma of the Pancreas — Y. Zhao, Z. Li, et al. (2019)

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