Pleural invasion

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Visceral pleural invasion. H&E stain. (WC)

Pleural invasion is the presence of tumour in the pleura. Pleural invasion is considered a poor prognosticator in lung cancer,[1][2] and important in determining the tumour stage in lung cancer staging.


Normal visceral pleura of the lung. Miller stain. (WC)

The visceral pleura is the pleura that covers the lung; tumour invasion into it is known as visceral pleural invasion (abbreviated VPI). The parietal pleural covers the chest wall.

The visceral pleura has two elastic layers:[3]

  • External elastic layer.
    • Usually thick/prominent.
    • Important for staging.
  • Internal elastic layer.
    • Thin - may be difficult to see.
    • Irrelevant for staging.

Images - normal pleural

Modified Hammar classification

Pleural invasion can be subgrouped as follows:[1]

Category Description Tumour stage (TNM staging)
PL0 † tumour confined to lung, not through elastic layer T(any)
PL1 † tumour beyond (external) elastic layer of the visercal pleura, not at pleural surface at least T2 ‡
PL2 tumour at surface of pleura, not in parietal pleura at least T2
PL3 tumour within parietal pleura and visceral pleura at least T3


  • † The interface between PL0 and PL1 is the most challenging. Use of an elastic stain is recommend when there is uncertainty.[3]
  • ‡ The up-staging of small tumours is not completely without controversy; there is data for lung adenocarcinomas less than 2 cm that suggests VPI is not an outcome predictor.[4]


  • Tumour close to visceral pleura, e.g. <1 mm - high probability of VPI.
  • Puckering of the visceral pleura overlying the tumour - suspicious for VPI.


Features - for PL1:

  • Must be through the external elastic layer.[3]


  • Tumour trapped within the (external) elastic layer is still PL0.[3]



Visceral pleural invasion. Miller stain. (WC)


See also


  1. 1.0 1.1 Travis, WD.; Brambilla, E.; Rami-Porta, R.; Vallières, E.; Tsuboi, M.; Rusch, V.; Goldstraw, P. (Dec 2008). "Visceral pleural invasion: pathologic criteria and use of elastic stains: proposal for the 7th edition of the TNM classification for lung cancer.". J Thorac Oncol 3 (12): 1384-90. doi:10.1097/JTO.0b013e31818e0d9f. PMID 19057261.
  2. Shimizu, K.; Yoshida, J.; Nagai, K.; Nishimura, M.; Ishii, G.; Morishita, Y.; Nishiwaki, Y. (Jul 2005). "Visceral pleural invasion is an invasive and aggressive indicator of non-small cell lung cancer.". J Thorac Cardiovasc Surg 130 (1): 160-5. doi:10.1016/j.jtcvs.2004.11.021. PMID 15999057.
  3. 3.0 3.1 3.2 3.3 Dacic, S. (Oct 2012). "Dilemmas in lung cancer staging.". Arch Pathol Lab Med 136 (10): 1194-7. doi:10.5858/arpa.2012-0282-CC. PMID 23020722.
  4. Nitadori, J.; Colovos, C.; Kadota, K.; Sima, CS.; Sarkaria, IS.; Rizk, NP.; Rusch, VW.; Travis, WD. et al. (Nov 2013). "Visceral pleural invasion does not affect recurrence or overall survival among patients with lung adenocarcinoma ≤ 2 cm: a proposal to reclassify T1 lung adenocarcinoma.". Chest 144 (5): 1622-31. doi:10.1378/chest.13-0394. PMID 23807749.