Malignant pleural mesothelioma is an aggressive malignancy arising from mesothelial cells of the pleura. Asbestos exposure is the most important risk factor — with a latency period of 20-50 years. Circumferential pleural thickening (rind-like), pleural effusion, encasement of the lung, and mediastinal pleural involvement are characteristic findings. It does not initially destroy lung parenchyma — invasion occurs by contiguous spread. It shows intense FDG uptake on PET-CT. Prognosis is poor — median survival is 12-18 months.
Age Range
50-80
Peak Age
65
Gender
Male predominant
Prevalence
Rare
Malignant pleural mesothelioma develops decades after inhalation of asbestos fibers (latency 20-50 years). Asbestos fibers (especially amphibole fibers — crocidolite and amosite) reach the pleural space and create chronic inflammation and DNA damage in mesothelial cells. This prolonged irritation leads to malignant transformation of mesothelial cells. The tumor grows diffusely along the pleural surface forming 'rind'-like thickening — seen on imaging as circumferential pleural thickening. The tumor encases the lung and narrows the hemithorax — causing volume loss. On CT, this thickening is of soft tissue density because the tumor is solid cellular. Enhancement reflects tumor vascularity. Mediastinal pleural involvement shows contiguous tumor spread — detected as loss of mediastinal fat planes on CT. Intense FDG uptake on PET-CT results from the tumor's high metabolic activity — glucose metabolism is increased. Pleural plaques (calcified or non-calcified) are independent evidence of asbestos exposure and may develop bilaterally separate from mesothelioma.
Circumferential rind-like pleural thickening along the pleural surface of a unilateral hemithorax — nodular, irregular, >1 cm — combined with the presence of contralateral or bilateral calcified pleural plaques is pathognomonic for mesothelioma. This combination definitively demonstrates asbestos exposure + malignant pleural disease. Mediastinal pleural involvement, ipsilateral volume loss, and pleural effusion provide additional diagnostic value. In benign asbestos pleuritis, pleural thickening is smooth and thin, and circumferential nodular thickening is not expected.
Circumferential pleural thickening — tumor grows diffusely along the pleural surface and encases the hemithorax like a rind. Thickness usually >1 cm, with nodular or irregular contour. Shows heterogeneous enhancement on contrast-enhanced CT.
Report Sentence
Circumferential, nodular pleural thickening is observed along the pleural surface of the left/right hemithorax, and malignant pleural mesothelioma should be primarily considered.
Mediastinal pleural involvement — pleural thickening extends to the mediastinal surface, mediastinal fat planes are lost. Pericardial involvement (pericardial thickening, effusion) may accompany. This finding is one of the most specific CT findings for differentiating malignancy from benign pleural disease.
Report Sentence
Pleural thickening extends to the mediastinal surface with loss of mediastinal fat planes, consistent with mediastinal pleural involvement.
Ipsilateral hemithorax narrowing and volume loss — tumor encases and compresses the lung, shrinking the hemithorax. Mediastinum may shift to the affected side. Interlobar fissure thickening and nodularity accompany.
Report Sentence
Volume loss and narrowing of the ipsilateral hemithorax is observed, suggestive of tumor encasement of the lung.
Pleural plaques — independent evidence of asbestos exposure. May be calcified or non-calcified. Usually bilateral, along costal and diaphragmatic pleura. Plaques develop independently from mesothelioma but confirm asbestos exposure.
Report Sentence
Calcified pleural plaques are observed along bilateral costal and diaphragmatic pleura, supporting asbestos exposure.
Intense FDG uptake in pleural thickening on PET-CT — SUVmax usually >4. Provides high sensitivity (95%+) and high specificity (80%+) for differentiating malignant pleural thickening from benign pleural disease. Plays a critical role in distant metastasis detection and staging.
Report Sentence
Intense FDG uptake (SUVmax: ...) is observed in pleural thickening on PET-CT, consistent with malignant pleural mesothelioma.
On MRI, the pleural tumor shows intermediate-to-high signal intensity on T2. MRI is superior to CT for assessing chest wall and diaphragm invasion — multiplanar imaging and high soft tissue contrast provide advantage.
Report Sentence
Intermediate-to-high T2 signal is observed in the pleural mass on MRI, and chest wall/diaphragm invasion should be assessed.
Unilateral pleural effusion — usually the initial presenting finding. May be massive and fill most of the hemithorax. Masks pleural thickening hidden beneath the effusion — post-drainage CT reveals the pleural thickening.
Report Sentence
Ipsilateral pleural effusion is observed, and post-drainage CT is recommended for evaluation of underlying pleural pathology.
Criteria
Histologically epithelioid cell predominance (50-70% incidence). Most common subtype.
Distinct Features
Best prognosis (median survival 14-19 months). Enhancement tends to be more homogeneous. Calretinin and WT-1 positive on immunohistochemistry.
Criteria
Histologically spindle cell (sarcomatoid) pattern predominance (10-20% incidence).
Distinct Features
Worst prognosis (median survival 4-8 months). More aggressive local invasion tendency — chest wall and diaphragm invasion more common. More heterogeneous enhancement and necrosis areas on CT.
Criteria
Coexistence of both epithelioid and sarcomatoid components (20-35% incidence). Each component must be at least 10%.
Distinct Features
Intermediate prognosis (median survival 10-14 months). Proportion of sarcomatoid component is inversely related to prognosis. Regional heterogeneity on CT — different components may show different enhancement.
Distinguishing Feature
In pleural metastasis (lung, breast, ovarian cancer), pleural thickening is usually nodular and focal — circumferential rind-like thickening is more typical of mesothelioma. Primary tumor history exists in metastasis. Asbestos exposure history and pleural plaques in mesothelioma. Contralateral involvement is more common in metastatic pleural thickening — mesothelioma usually starts unilaterally.
Distinguishing Feature
Primary pleural lymphoma (DLBCL) is rare and usually presents as a localized mass — diffuse circumferential thickening as in mesothelioma is not expected. B symptoms (fever, night sweats, weight loss) are prominent in lymphoma. Asbestos exposure and pleural plaques are not expected in lymphoma. Treatment response to chemotherapy is excellent in lymphoma (limited in mesothelioma). Both are FDG avid on PET-CT — clinical context is distinguishing.
Distinguishing Feature
Solitary fibrous tumor is usually a well-defined, pedunculated, localized pleural mass — does not show diffuse circumferential thickening. Asbestos exposure history is not expected in SFT. SFT usually has benign behavior — hypoglycemia (Doege-Potter syndrome) may accompany. Intense homogeneous enhancement is typical in SFT — heterogeneous in mesothelioma. Invasion is not expected in SFT (except malignant variant).
Distinguishing Feature
Pleural spread of lung adenocarcinoma usually presents as focal pleural nodules or effusion — diffuse circumferential rind-like thickening is rare. Primary parenchymal mass or nodule is seen in lung carcinoma — parenchymal mass is not expected in mesothelioma. Asbestos exposure history and pleural plaques support mesothelioma. On immunohistochemistry, adenocarcinoma is TTF-1(+)/calretinin(-), mesothelioma is calretinin(+)/TTF-1(-).
Urgency
urgentManagement
surgicalBiopsy
NeededFollow-up
3-monthMalignant pleural mesothelioma is an aggressive tumor requiring early diagnosis and multidisciplinary approach. Definitive diagnosis is histopathological via video-assisted thoracoscopic surgery (VATS) biopsy or CT-guided pleural biopsy — fine needle aspiration is insufficient (30% false negative). Immunohistochemistry is critical for differential diagnosis: calretinin, WT-1, CK5/6 positive; TTF-1, CEA, BerEP4 negative. Staging is by TNM (IMIG/UICC 8th edition) — CT + PET-CT + MRI (diaphragm/chest wall invasion). Treatment: (1) Early stage (T1-T3, N0-N1) — surgery (extrapleural pneumonectomy or pleurectomy/decortication) + chemotherapy (cisplatin/pemetrexed) + radiotherapy (trimodality), (2) Advanced stage — chemotherapy (cisplatin/pemetrexed first-line, nivolumab/ipilimumab immunotherapy second-line), (3) Palliative — pleural effusion control (pleurodesis, indwelling catheter). Prognosis is poor — median survival 12-18 months (20-24 months in surgically eligible).
Malignant pleural mesothelioma is an aggressive tumor with poor prognosis (median survival 12-18 months). Treatment: combination of chemotherapy (cisplatin + pemetrexed), surgery (extrapleural pneumonectomy or pleurectomy/decortication), and radiotherapy. Immunotherapy (nivolumab + ipilimumab) is a new treatment option. Asbestos exposure history is important for legal and occupational health purposes.