Pleural tumours: mesothelioma and solitary fibrous tumour
- Lesion
Mesothelioma is an aggressive cancer of the pleural lining caused mostly by asbestos. Solitary fibrous tumour is a usually benign pleural mass.
What it is
Most tumours in the pleura are metastases, especially from lung and breast. The two primary tumours to know are malignant mesothelioma, a diffuse asbestos-related cancer with a latency of decades and a poor prognosis, and solitary fibrous tumour, a localised fibroblastic tumour defined by a NAB2::STAT6 fusion and unrelated to asbestos. Immunohistochemistry separates mesothelioma from adenocarcinoma.
Structure
- Mesothelioma gross: thick, soft, gelatinous grey-pink rind that encases the lung and fills the fissures, with effusion.
- Epithelioid: cuboidal or flattened cells forming tubules and papillae, like adenocarcinoma.
- Sarcomatoid: malignant spindle cells like a sarcoma; biphasic: both.
- Solitary fibrous tumour: firm, well-circumscribed mass on a pedicle; patternless spindle cells among collagen and branching staghorn vessels.
Step by step
- Inhaled asbestos fibres (especially amphiboles) migrate to the pleura.
- Fibres cause chronic inflammation, oxidant injury and DNA damage in mesothelial cells.
- Over decades the cells lose CDKN2A, BAP1 and NF2 tumour suppressors.
- The tumour spreads over the pleural surfaces and invades the chest wall, lung and mediastinum.
- Solitary fibrous tumour arises from a NAB2::STAT6 fusion that creates a chimeric transcription factor.
Mesothelioma vs lung adenocarcinoma in the pleura
| Feature | Epithelioid mesothelioma | Adenocarcinoma |
|---|---|---|
| Growth | Diffuse rind encasing the lung | Mass in the lung, pleural nodules |
| Positive markers | Calretinin, WT1, CK5/6, D2-40 | TTF-1, napsin A, claudin-4, BerEP4, CEA |
| Main cause | Asbestos | Tobacco |
| Smoking effect | No added risk | Strong risk factor |
Markers
- Calretinin
- WT1
- CK5/6
- D2-40 (podoplanin)
- BAP1 loss
- STAT6
- CD34
Clinical notes
- Mesothelioma: chest pain, dyspnoea and recurrent effusions; asbestosis is present in only a minority.
- Median survival is about a year; peritoneal, pericardial and tunica vaginalis mesotheliomas also occur.
- Solitary fibrous tumour can cause hypoglycaemia (IGF-2) or clubbing; resection is usually curative.
Test yourself
Think of the answer, then tap the question to see it.
Which immunohistochemical markers support mesothelioma over adenocarcinoma?
Calretinin, WT1, CK5/6 and podoplanin positive, with claudin-4, BerEP4 and TTF-1 negative.
What is the latency between asbestos exposure and mesothelioma?
Usually decades, about 25 to 45 years.
What fusion gene defines solitary fibrous tumour?
NAB2::STAT6, shown by nuclear STAT6 staining.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Mesothelioma (MedlinePlus, US National Library of Medicine, 2025); Pleural Disorders (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.