Types of Lung Cancer

The small cell refers to the size of the cells making up the lung cancer when looked at under the microscope. The reason for distinguishing between the two is that treatment is different. Small cell lung cancer is sensitive to chemo radiation, where as the Non small cell cancers are treated with surgery if possible, and with chemotherapy and  radiation.

The World Health Organization ( http://www.who.int ) has recently had a panel of pathologists meet to upgrade the classification of Lung Malignancies. The commonest types of non small cell lung cancer in a group of 200 patients being operated on are;

To distinguish these types one from another requires a vast amount of experience in Pathology and now Histochemical analysis aids in the diagnosis. These techniques use special staining for chemicals in the cancers and can differentiate primary lung cancers from ones that have spread to the lungs such as malignant melanoma, prostate cancer, bowel cancer, breast cancer, etc... Electron microscopy is not done routinely on these cancers but in some institutions is used regularly.

Large Cell Undifferentiated Carcinoma	Small Cell Carcinoma
Squamous Cell Carcinoma	Typical Carcinoid tumour of the lung

Stains used for helping to differentiate one tumour from another:

1. High and low molecular weight keratin - squamous cell carcinoma
2. PAS-Diastase for mucin - adenocarcinoma
   
3. Chromogranin/synaptophysin, low molecular weight keratin - carcinoid, atypical carcinoid, neuroendocrine and small cell carcinoma
   
4. Keratins, S100, HMB45 - metastatic melonoma, PSA for metastatic prostate, etc...