Basal Cell Carcinoma This is the most common type of malignancy and is easily treated when detected early. It appears as a hard nodule with a pearly appearance. If left untreated, it can ulcerate the skin and invade surrounding tissues. Squamous Cell Carcinoma While less common than basal cell carcinoma, this cancer can be very aggressive and spread quickly. It can appear as scaly red patches, open sores, elevated growths with a central depression, or warts that crust over and bleed. Melanoma Melanoma is the most dangerous form of skin cancer. It most often starts on the skin but can progress to other parts of the body including the eyes. It can be life-threatening if left untreated but with early detection and surgical intervention, there is an excellent survival rate.