Cancer is tissue which grows at an uncontrollable and unpredictable rate. In the skin, there are three main forms:
The names refer to the cell types in the top layer of the skin (the epidermis) from which these cancers are derived.
The most common types of skin cancers are basal cell carcinoma and squamous cell carcinoma. If not removed completely, basal cell carcinoma and squamous cell carcinoma can enlarge from the point where they first occur and can invade and destroy structures in their path. Basal cell carcinoma is unlikely to spread to distant parts of the body (metastasize). However, some squamous cell carcinomas can metastasize. These types of skin cancers are generally recognized in their early stages and are therefore easily cured.
Malignant melanoma, on the other hand, may be life threatening if not treated early. It usually appears as a brownish-black spot or bump on the skin which enlarges and sometimes bleeds. Sometimes melanomas arise in moles which have been present for many years.