Non-small cell lung carcinoma

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Non-small cell lung carcinoma, abbreviated NSCLC, is a malignant epithelial neoplasm of the lung that is not small cell carcinoma of the lung.

It can be understood as a synonym for large cell carcinoma. It is umbrella term that includes squamous cell carcinoma of lung, adenocarcinoma of the lung and adenosquamous carcinoma of the lung.[1]

In the clinical context, it is usually referred to as non-small cell lung cancer; this ignores the fact that not all non-small cell lung cancer fits into the carcinoma category.

Poorly differentiated carcinoma of the lung and poorly differentiated lung carcinoma redirect to this article.

General

  • Non-small cell lung carcinoma can be considered a waffle diagnosis and as such its use should be limited.
    • It is preferable to be more specific if this is possible, i.e. call adenocarcinoma or squamous cell carcinoma.
  • Historically, it was sufficient to differentiate between small cell and non-small cell carcinomas, as the treatment for all non-small cell lung carcinomas was the same.
  • Small cell carcinoma is typically considered non-surgical disease; thus, non-small cell carcinoma or poorly differentiated carcinoma, as a diagnosis, is less likely to exclude surgery as an option.

Clinical:

  • Radiologic findings should not be suggestive of a metastasis.

Microscopic

Features:

  • Typically large cells with abundant cytoplasm.
  • +/-Nucleoli.
  • No stippled chromatin.

DDx:

IHC

Features:

Note:

  • Immunostains should not favour adenocarcinoma or squamous cell carcinoma - see Sloan-Kettering algorithm below.

Adenocarcinoma versus squamous carcinoma

Sloan-Kettering algorithm - Rekhtman et al.:[2]

TTF-1\p63 p63 -ve (0% of cells) p63 +ve <50% of cells p63 +ve >=50% of cells
TTF-1 +ve >=50% of cells Adenocarcinoma Adenocarcinoma Adenocarcinoma
TTF-1 +ve <50% of cells Adenocarcinoma Adenocarcinoma Squamous carcinoma
TTF-1 -ve (0% of cells) Adenocarcinoma CK5/6 to determine Squamous carcinoma

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Lung, Left Lower Lobe, Core Biopsy: 
- POORLY DIFFERENTIATED CARCINOMA, see comment. 

COMMENT: 
The tumour stains as follows: 
POSITIVE: EMA, AE1/AE3. 
NEGATIVE: TTF-1, chromogranin A, synaptophysin, CD56, CD45, CK5/6, p63.

The morphology would be compatible with small cell carcinoma or basaloid 
squamous cell carcinoma.  

The neuroendocrine markers (chromogranin A, synaptophysin, CD56) and the squamoid 
markers available (p63, CK5/6) are negative; thus, the tumour is not further classified. 

See also

References

  1. Song, Z.; Lin, B.; Shao, L.; Zhang, Y. (Sep 2013). "Therapeutic efficacy of gefitinib and erlotinib in patients with advanced lung adenosquamous carcinoma.". J Chin Med Assoc 76 (9): 481-5. doi:10.1016/j.jcma.2013.05.007. PMID 23769878.
  2. Rekhtman, N.; Ang, DC.; Sima, CS.; Travis, WD.; Moreira, AL. (Oct 2011). "Immunohistochemical algorithm for differentiation of lung adenocarcinoma and squamous cell carcinoma based on large series of whole-tissue sections with validation in small specimens.". Mod Pathol 24 (10): 1348-59. doi:10.1038/modpathol.2011.92. PMID 21623384.