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Malignant mesothelioma is a rare, aggressive tumor arising from mesothelial cells of the pleura, peritoneum, pericardium, or tunica vaginalis, most commonly affecting the parietal pleura. It is strongly associated with asbestos exposure and has a poor prognosis.
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Mesothelioma - causes, symptoms, diagnosis, treatment, pathology
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| Risk Factor | Details |
|---|---|
| Asbestos exposure | Primary and most significant risk factor (80–90% cases) |
| Latency period | Typically 20–50 years after exposure |
| Radiation, SV40 virus | Rare or unproven contributors |
| Smoking | Not a direct cause, but synergistic with asbestos for lung cancer |
Common sites:
Common mesothelioma sites: A schematic showing the anatomical location and relative frequency of mesothelioma. Pleural mesothelioma is the most common disease form with a rate of >85%, followed by peritoneal mesothelioma (7–15%). Pericardial and testicular forms are rare (<1%).
Fennell, D.A., Sekido, Y., Baas, P. et al. Pleural mesothelioma. Nat Rev Dis Primers 11, 56 (2025). https://doi.org/10.1038/s41572-025-00640-3
Histopathological subtypes:
| Histological Subtype | Frequency | Prognosis |
|---|---|---|
| Epithelioid | ~60% | Best prognosis |
| Sarcomatoid | ~10–20% | Poor prognosis |
| Biphasic (mixed) | ~20–30% | Intermediate prognosis |
Pathological features of mesothelioma: a, Cell block preparation from a pleural effusion showing clusters of atypical mesothelial cells and inflammatory cells. b, Epithelioid mesothelioma with relatively uniform cells containing moderate cytoplasm, forming papillary structures with fibrovascular cores. c, Sarcomatoid mesothelioma with spindle cells showing varying degrees of nuclear atypia (the less atypical areas especially in the centre of the field would be called desmoplastic component). d, Biphasic mesothelioma with sarcomatoid (top) and epithelioid (bottom) components. Note chondrosarcomatous differentiation in the sarcomatous component, which is not known to have any clinical significance. e, Immunohistochemical staining shows BAP1 deletion in tumour cells; positive normal cells in stroma, which serve as internal control. f, Immunohistochemical staining shows MTAP deletion in a cytological preparation of pleural effusion. Cells staining positive are coloured brown.
Fennell, D.A., Sekido, Y., Baas, P. et al. Pleural mesothelioma. Nat Rev Dis Primers 11, 56 (2025). https://doi.org/10.1038/s41572-025-00640-3