Non-small cell lung carcinoma

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.

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:

• Squamous cell carcinoma of the lung.
• Adenocarcinoma of the lung.
• Small cell carcinoma of the lung.
• Large cell variant of small cell carcinoma of the lung.
• Lung metastasis - imaging suggestive of a metastasis or a history of malignancy.

IHC

Features:

• Lack of staining with neuroendocrine markers (chromogranin A -ve, synaptophysin -ve, CD56 -ve).
• Keratins +ve.

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.:

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

• Lung tumours.
• SUV.