IgG4-related pulmonary pseudotumor and pleuritis mimicking lung cancer and asbestos plaque: A case report

Our plain-English summary of IgG4-related pulmonary pseudotumor and pleuritis mimicking lung cancer and asbestos plaque: A case report, by R. Kamada, M. Hibino, H. Higa, et al (Respiratory Medicine Case Reports, 2026).

The study

• Authors: R. Kamada, M. Hibino, H. Higa, S. Watanabe, K. Maeda, S. Horiuchi, N. Ishikawa, T. Kondo
• Journal: Respiratory Medicine Case Reports
• Published: 2026;59:102363
• Type of article: Case report
• Read it: PubMed · Publisher · Free full text

Abstract

We report the case of a 70-year-old man who presented with a two-month history of cough. He had a history of asbestos exposure. Chest imaging revealed a mass on the right upper lobe, bilateral hilar and mediastinal lymphadenopathies, bilateral pleural thickening, and partial calcification of the right pleura. Lung cancer and asbestos-related pleural disease were suspected initially. However, neither transbronchial lung biopsy nor computed tomography-guided percutaneous needle lung biopsy demonstrated evidence of malignancy. Subsequent video-assisted thoracoscopic surgery revealed storiform fibrosis, dense lymphoplasmacytic infiltration, and numerous IgG4-positive plasma cells in the lung mass along with asbestos bodies. The pleura exhibited similar histopathological features. The patient's elevated serum IgG4 levels, in combination with these histological features, fulfilled both the 2019 ACR/EULAR classification criteria and the Japanese comprehensive diagnostic criteria for IgG4-related disease (IgG4-RD). The patient was treated with oral prednisolone, resulting in resolution of the lung mass, symptom improvement, and a decline in serum IgG4 levels. IgG4-RD is an immune-mediated condition characterised by T helper type 2 cell activation, elevated serum IgE levels, and regulatory T cell (Treg) dysfunction. The development of Treg dysfunction after asbestos exposure suggests a potential mechanistic link between asbestos and the pathogenesis of IgG4-RD. This case highlights the diagnostic challenges posed by IgG4-related lung disease, which can mimic malignancy and asbestos-related pathology, underscoring the importance of biopsy for accurate diagnosis. It also suggests a possible association between asbestos exposure and IgG4-RD development.

© 2025 The Authors.

In plain English

This case report described a 70-year-old man in Japan with a two-month cough. He had worked for 30 years at a construction site with documented asbestos exposure, ending about 10 years earlier, and had smoked 20 cigarettes a day for 30 years. Scans showed a mass about 4 cm across in the right upper lung, enlarged lymph nodes, thickened pleura (lung lining) on both sides, and partial calcification of the right pleura. Doctors were concerned about lung cancer, pleural plaques or malignant pleural mesothelioma. A transbronchial lung biopsy and a CT-guided needle biopsy found no cancer but did not rule it out. A surgical biopsy found scarring and inflammation rich in IgG4-positive plasma cells, scattered asbestos bodies, and no cancer. The pleura showed typical plaques plus similar inflammation. His blood IgG4 level was 501 mg/dL, and he was diagnosed with IgG4-related disease, an immune condition. After four months of the steroid prednisolone, the lung mass had completely resolved. The authors concluded that the case supports a possible link between asbestos exposure and IgG4-related respiratory disease, and called for further studies.

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 70-year-old man with a two-month cough, referred to a hospital in Fujisawa, Japan; dates of care not given
• Exposure: Work at a construction site with documented asbestos exposure for 30 years, ending about 10 years before; fiber type not stated. He also smoked 20 cigarettes per day for 30 years.
• Main results:
  • CT scans of the patient showed thickening of the pleura on both sides and partial calcification of the right pleura, along with a lung mass and enlarged hilar lymph nodes
  • The patient had a transbronchial lung biopsy and a CT-guided percutaneous needle biopsy; neither found cancer
  • After these biopsies, the possibility of primary lung cancer with lymph node spread remained, so a surgical biopsy was done
  • Surgical (VATS) biopsy of the lung mass showed scattered asbestos bodies and no cancer, along with storiform fibrosis and lymphoplasmacytic infiltration
  • In the lung tissue, IgG4-positive plasma cells made up more than 40% of IgG-positive plasma cells, with more than 10 IgG4-positive plasma cells per high-power field
  • The pleural biopsy showed typical plaques as well as features resembling the lung mass, consistent with IgG4-related pleuritis
  • The patient's blood immunoglobulin G was 2154 mg/dL and IgG4 was 501 mg/dL, both elevated
  • The patient scored 33 points on the 2019 ACR/EULAR classification criteria for IgG4-related disease
  • After four months of oral prednisolone, which was started at 30 mg/day, the lung mass had completely resolved, the pleural lesions had thinned slightly, and the lymph nodes had mildly decreased in size
  • Serum IgG4 in the patient fell to 113 mg/dL with treatment
  • At 18 months the prednisolone dose had been tapered to 7 mg/day and the patient remained clinically stable
• The authors' conclusion: The authors concluded that this case supports a possible link between asbestos exposure and IgG4-related respiratory disease, that biopsy is needed to distinguish it from cancer, and that further studies should clarify asbestos's role

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer, Asbestos Exposure, Bilateral, Pleural Thickening, Pleura, Asbestos-Related Pleural Disease, Biopsy, Video-Assisted Thoracoscopic Surgery (VATS).

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