Melanocytes are in the epidermis. They contain malanin, the pigment of the skin. Benign tumors are not cancerous. In the skin, examples of benign tumors are moles and non-cancerous warts. Most people have between 10 to 40 moles.
Malignant tumors are cancerous.
Cancer cells can spread to nearby healthy cells and destroy them. The cancerous cells can also invade other parts of the body. This usually occurs on areas of your skin that have been exposed to the sun. It appears as a small raised bump that has a smooth, pearly appearance or a persistent red scaly patch. Basal cell cancers may spread to surrounding tissue, but usually do not spread to other parts of the body.