Melanoma of the pleura mimicking malignant mesothelioma: a rare and rapidly progressive pleural disease

Our plain-English summary of Melanoma of the pleura mimicking malignant mesothelioma: a rare and rapidly progressive pleural disease, by B. Edland, C. Stanley, F.H.X. Yap, et al (BMJ Case Reports, 2025).

The study

• Authors: B. Edland, C. Stanley, F.H.X. Yap, Y. Weerakkody
• Journal: BMJ Case Reports
• Published: 2025;18(1)
• Read it: PubMed · Publisher · Free full text

In plain English

This article was a case report from Royal Perth Hospital in Western Australia. It described a woman in her 60s with rheumatoid arthritis who came to an emergency department short of breath. Scans showed fluid around the left lung and nodular thickening of the pleura, the lining around the lung. Because the patient had a history of exposure to asbestos, the doctors at first strongly suspected malignant mesothelioma. The article did not describe that exposure further. Tests on the fluid and a pleural biopsy instead showed melanoma, a cancer of pigment cells. No starting site was found on skin or eye examination or on a PET scan. The fluid built up quickly and needed drainage of up to 1 litre every 48 hours. Single-drug immunotherapy with nivolumab brought no response. The disease progressed rapidly, and the patient moved to comfort care within 3 months of diagnosis. The authors stated that only nine other such cases had been reported in the English literature. They concluded that melanoma should be on the list of possible diagnoses for cancers in organs or lymph nodes, even without a history of melanoma.

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 woman in her 60s who came to an emergency department in Western Australia; she had rheumatoid arthritis and connective tissue disease-associated interstitial lung disease
• Exposure: a history of exposure to asbestos-related materials; the article gives no fiber type, job, duration or dose
• Main results:
  • CT showed a moderate left-sided pleural effusion with nodular circumferential pleural thickening, which together with the asbestos history initially strongly suggested malignant mesothelioma
  • Abnormal cells in the pleural fluid were positive for SOX10, Melan A and S100 and negative for calretinin, EMA, p40 and WT1; a diagnosis of malignant melanoma was made and confirmed by CT-guided pleural biopsy
  • Dermatological and ocular examination and PET scanning found no primary cutaneous or subcutaneous lesion
  • Pleural fluid built up rapidly, and an indwelling pleural catheter needed drainage of up to 1 L every 48 hours
  • The disease was BRAF and KIT wild type, so targeted therapies were unsuitable; single-agent nivolumab was given, the disease progressed rapidly with no response, and the patient moved to comfort-based care within 3 months of diagnosis
  • The authors stated that, to their knowledge, only nine other cases of pleural melanoma with unknown primary had been reported in the English literature
• The authors' conclusion: The authors concluded that melanoma should be included in the differential diagnosis of visceral organ or nodal malignancies even without a history of cutaneous, ocular or mucosal melanoma. They also stated that pleural fluid analysis should include cytological and immunohistochemical evaluation, and that prompt treatment is critical given the disease's aggressive nature.

Topics

Medical terms in this study, explained in our Lexicon: Pleura, Mesothelioma.

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