han the usual number of moles and continue to develop new moles as they get older. Dysplastic nevi usually run in families.
             Basal-cell cancers are the most common skin cancers, accounting for about 70 percent of total cases (Lamberg 65). They are the most easily treated. Basal-cell cancer affects the skin's fifth layer of skin, the basal layer. Basal-cell cancers occur mostly where the sun strikes the hardest. They start as a small bump and later may grow wider and more elevated, often with a depression in the middle. Their surface is shiny and pearly with tiny blood vessels. They seldom spread or grow, and they may develop into a crust or sore that does not heal.
             Malignant melanomas are the most dangerous skin cancers. They start in the skin's pigment, making melanocytes. They start as small growths similar to moles, and may turn red, white, or blue, or even lose their color as they enlarge. The people that are most susceptible to this often have 100 or more moles by the time they reach adulthood.
             A rare type of skin cancer, called Karposi's sarcoma, is one of the primary indications of AIDS (acquired immune deficiency syndrome). If one develops Karposi's sarcoma, he or she may develop bluish red or brown swollen areas that resemble bruises or moles. These growths often continue to develop into thickened bumps and even large tumors. Karposi's sarcoma is only rarely the cause of death in AIDS patients; usually they succumb to other infections.
             Some lesions of the skin are "precancerous", meaning that they have the potential to become cancerous. One of these types is the actinic keratosis, which is a scaly, reddened area that is sometimes thickened. Actinic keratoses may develop into squamous-cell cancers. Thirty percent of the cancers a dermatologist treats are squamous-cell cancers (Lamberg 65). If left untreated, they can spread through the body very quickly. They are ...