Malignant pleural mesothelioma (TNM staging)

Last revised by Bruno Di Muzio on 19 Apr 2020

Below is the eighth edition of the TNM staging system for malignant pleural mesothelioma, which was published in 2018 1.

T - Tumor
  • Tx: primary tumor cannot be assessed
  • T0: no evidence of primary tumor
  • T1
    • involving ipsilateral parietal pleura (inc. mediastinal and diaphragmatic pleura) +/- visceral pleura
  • T2
    • involving any of the ipsilateral pleural surfaces with at least one of the following features:
      • confluent visceral pleural tumor (including the fissures)
      • involvement of diaphragmatic muscle
      • invasion of the lung parenchyma
  • T3
    • involving all of the ipsilateral pleural surfaces with at least one of the following features:
      • invasion of the endothoracic fascia
      • extension into the mediastinal fat
      • solitary, completely resectable focus invading soft tissues of the chest wall
      • non-transmural involvement of the pericardium
  • T4
    • involving all of the ipsilateral pleural surfaces with at least one of the following features:
      • any rib involvement
      • invasion of the peritoneum through the diaphragm
      • invasion of any mediastinal organ (inc. myocardium)
      • direct extension to the contralateral pleura
      • invasion of the spine or brachial plexus
      • transmural invasion of the pericardium (+/- pericardial effusion)
N - Nodes
  • Nx: nodes cannot be assessed
  • N0: no evidence of nodal involvement
  • N1: ipsilateral bronchopulmonary, hilar, or mediastinal nodal involvement (inc. internal mammary, peridiaphragmatic, pericardial fat pad, or intercostal lymph nodes)
  • N2: contralateral bronchopulmonary, hilar, or mediastinal lymph nodes or ipsilateral or contralateral supraclavicular lymph nodes
M - Metastases
  • Mx: presence of metastases cannot be assessed
  • M0: no evidence of distant metastases
  • M1: distant metastases present

Stage groupings 

  • Stage IA: T1, N0, M0
  • Stage IB: T2 or 3, N0, M0
  • Stage II: T1 or 2, N1, M0
  • Stage IIIA: T3, N1, M0
  • Stage IIIB: T1-3, N2, M0 or T4, any N, M0
  • Stage IV: any T, any N, M1

Most Stage I and II tumors are resectable. Some stage III tumors may be resectable.

Previous editions

The seventh edition had separate T1a and T1b categories but these were combined following a survival analysis showing no difference between these two groups 3. The seventh edition also had an extra category for nodal involvement 4. Intrapleural (previous N1) and extrapleural (previous N2) lymph nodes are now combined into one category (N1) and previous N3 nodes have been moved into the N2 category.

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Cases and figures

  • Figure 1: mesothelioma - gross pathology
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  • Case 1: contralateral nodes
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  • Case 2
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  • Case 3: T4 with rib erosion
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  • Case 4: Stage IV T2 cN1 M1
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