Moles are pigmented nodules found on the skin of almost all humans. Made up of groups of
melanocytes (epidermal cells), or
nevus cells, they vary greatly in size and shape and range from flat to raised and smooth to hairy. Moles are flesh-colored, brownish yellow, or black. They appear in childhood, and at adolescence or during pregnancy they may
enlarge and darken. They often disappear as people get older.
Moles are generally benign. Rarely, they become involved with the skin cancers called malignant melanomas. Only 20 to 30 percent of all such tumors result from
melanocytes in moles, so mole removal purely for preventative reasons is not recommended. Moles that enlarge suddenly, change color, bleed, become painful, or are subject to infection and irritation, however, may safely be removed. They should then be analyzed in a laboratory to see if they are cancerous.