In medicine (dermatology), there are several different types of cancer referred to under the general label of skin cancer. The most common types are squamous cell carcinoma and basal cell carcinoma, while the most dangerous is malignant melanoma.
Skin cancer is an increasingly common condition, in part attributed to increased exposure to ultraviolet radiation, against which no level of sun screens offer any decisive protection. The increased exposure is mainly due to the recent popularity of sun tanning (sun bathing), but in part also due to ozone depletion and the consequently increased levels of ultraviolet radiation.
Pathology
Squamous cell carcinoma is a malignant epithelial tumor which originates in epidermis, squamous mucosa or areas of squamous metaplasia.
Macroscopically, the tumor is often elevated, fungating, or may be ulcerated with irreguliar borders. MIcroscopically, tumor cells destroy the basement membrane and form sheets or compact masses which invade the subjacent connective tissue (dermis). In well differentiated carcinomas, tumor cells are pleomorphic/atypical, but resembling normal keratinocytes from prickle layer (large, polygonal, with abundant eosinophilic (pink) cytoplasm and central nucleus). Their disposal tends to be similar to that of normal epidermis: immature/basal cells at the periphery, becoming more mature to the centre of the tumor masses. Tumor cells transform into keratinized squames and form round nodules with concentric, laminated layers, called "cell nests" or "epithelial/keratinous pearls". The surrounding stroma is reduced and contains inflammatory infiltrate (lymphocytes). Poorly differentiated squamous carcinomas contain more pleomorphic cells and no keratinization. 1
Minor surface skin cancers are readily treatable by simple surgery, but if the cancer is allowed to grow then it will penetrate through the layers of skin and affect the lymphatic system. It may also metastasize and spread to other parts of the body.
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