CONTENTS:

5.5 Squamous Cell Lung Carcinoma
5.6 Large Cell Carcinoma
5.7 Sarcomatoid Carcinoma

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It’s not how you look, it’s how you feel in the dark that counts!

5.5  Squamous Cell Lung Carcinoma

 
Squamous cell lung carcinoma represents between 20 % and 30 % of all lung cancers in the U.S.  Before the early to mid-1980s, squamous cell carcinoma of the lung was the most common histological type.  Adenocarcinoma of the lung is more the most common histological type, particularly in women.

The morphological features of squamous carcinoma cells which are diagnostic histologically, include:

• keratin production by the tumor cells,
• intercellular desmosomes or ‘intercellular ‘bridges,’
• absence of mucin production.

Unlike adenocarcinomas that tend to be peripherally located in the lung, squamous carcinomas are more centrally located, with 60 to 80 % arising in the proximal portions of the tracheobronchial tree.  A minority of cases occur peripherally and may be associated with bronchiectasis cavities or scars.

There is believed to be a progression from squamous metaplasia to dysplasia, to carcinoma in-situ to invasive squamous carcinoma.

Figure 5.4  Diagram of the Origin of Squamous Cell Carcinoma

Gosh, that looks like a big purple jelly fish.

Hector, if you were stung by a jelly fish, I’d be the first to pee on you.

Errr thanks Moose…I think.

Figure 5.5  Squamous Cell Carcinoma of the Lung.

A. Macroscopic appearance of a central (bronchial) lung tumor.
B. Diagnostic bronchial brushings cytology shows large cells with
prominent nucleoli. (PAP x 63). C. Photomicrograph of the
histology shows groups of infiltrating cancer cells associated
with keratin formation. (H&E x40).

Subsets of Squamous Cell Lung Carcinoma

 
A small subset of central, well-differentiated squamous cell lung carcinoma occur as exophytic, endobronchial, papillary lesions.  Most patients with exophytic endobronchial squamous cell carcinoma have a low-grade, early-stage tumor at diagnosis that has a good prognosis. Five-year survival rates are greater than 60 %.

The 2004 World Health Organization (WHO) classification system includes several variants of squamous lung carcinoma:

Papillary squamous cell carcinoma: characterized by exophytic and endobronchial growth patterns and proximal tumors.

Small cell, squamous cell carcinoma: composed of small basaloid cells resembling classic small cell carcinoma, but with large nuclei and prominent nucleoli.

Clear cell squamous carcinoma: with clear cell features and the clear cell areas involving between 10 to 20 % of the tumor.  Clear cell change is relatively common in both squamous cell carcinoma and adenocarcinoma.

Basaloid squamous cell carcinoma: characterized histologically by prominent peripheral palisading of cell nuclei (rather like the basal epithelial layer of the bronchi).

Dyslexic man walks into a bra.

5.6 Large Cell Carcinoma

 
Large cell carcinoma of the lung has histology that lacks glandular or squamous differentiation by light microscopy and has no cytological features of small cell carcinoma. Large cell carcinoma is a diagnosis of exclusion and includes all poorly differentiated Non-Small Cell Carcinomas (NSLC) that cannot be classified further by routine light microscopy.

However, using a combination of immunohistochemistry (IHC) and electron microscopy evidence of squamous, glandular, or neuroendocrine differentiation have been demonstrated in 90 % of cases.

Because large cell carcinoma of the lung represents a diagnosis of exclusion, it is inappropriate to apply the term to small endoscopic biopsies or cytology specimens. The term NSCLC would be more appropriate.

The behavior of large cell carcinoma is that of a poorly differentiated cancer. These tumors usually present as a large peripheral mass with prominent necrosis.

Speaking of large Doc, a woman walks into a pharmacy and asks if they sell extra large condoms…

Where’s this going Moose?

The pharmacist asks, ‘do you want to buy some’ and the woman says ‘no, but do you mind if I stand here and wait to see who does’?

5.7 Sarcomatoid Carcinoma

 
Sarcomatoid carcinoma is a collective term for a heterogeneous group of NSCLCs that contain components of sarcoma or sarcoma-like cells.  These are rare primary lung tumors that make up 1 % of all lung cancers. Sarcomatoid carcinomas have a poor prognosis and include the following main variants:

Spindle cell carcinoma:

the histology shows spindle-shaped malignant cells without morphological differentiation.  Immunohistochemistry shows positive staining for keratin markers.

Pleomorphic carcinoma:

this is the term used for a non-small carcinoma, (adenocarcinoma or squamous carcinoma) combined with greater than 10 % of a second component of either giant cells or spindle cells.

Giant cell carcinoma:

the histology shows large ‘giant‘ tumor cells (> 40 microns in diameter and multinucleated) and can be seen in otherwise typical squamous cell carcinoma or adenocarcinoma of the lung.  The giant cells comprise at least 10 % of the tumor.

Carcinosarcoma:

the histology shows a typical carcinoma (squamous or adenocarcinoma) combined with sarcomatous elements (cartilage, bone, or skeletal muscle) that include rhabdomyosarcoma, osteosarcoma, and chondrosarcoma.

Pulmonary blastoma:

these are biphasic malignancies that have an adenocarcinoma component that has the appearance of fetal adenocarcinoma and a stroma that resembles that seen in Wilms tumor.  They are usually very large at the time of presentation and are very aggressive.

Do you know, if there was an award for laziness I’d probably have somebody pick it up for me.

REFERENCES:

Pao W, Girard N. (2011). New driver mutations in non-small-cell lung cancer. Lancet Oncol 12 (2): 175-80, 2011. (Retrieved Feb 12^th 2015): http://www.ncbi.nlm.nih.gov/pubmed/21277552?dopt=Abstract

Travis, WD, Brambilla, E, Muller-Hermlink, HK, Harris, CC (eds). World Health Organization classification of tumours. Pathology and genetics of tumours of the lung, pleura, thymus and heart. IARC Press. Lyon 2004.

More references for this section are on this page .

PATIENT INFORMATION:

LUNGevity Foundation Squamous Cell Lung Cancer (Retrieved 22/07/2018) https://lungevity.org/for-patients-caregivers/lung-cancer-101/types-of-lung-cancer/squamous-cell-lung-cancer

National Cancer Institute  Non-Small Cell Lung Cancer Treatment: General Information About Non-Small Cell Lung Cancer (Retrieved 20^th April 2015): http://www.cancer.gov/cancertopics/pdq/treatment/non-small-cell-lung/Patient/page1

More patient information for this section is on this page .

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