Moles can appear anywhere on the skin. They are usually brown in color but can be skin colored and various sizes and shapes. The brown color is caused by melanocytes, special cells that produce the pigment melanin.
Moles probably are determined before a person is born. Most appear during the first 20 years of life, although some may not appear until later. Sun exposure increases the number of moles, and they may darken. During the teen years and pregnancy, moles also get darker and larger and new ones may appear.
Each mole has its own growth pattern. The typical life cycle of the common mole takes about 50 years. At first, moles are flat and tan like a freckle, or they can be pink, brown, or black in color. Over time, they usually enlarge and develop hairs. As the years pass, moles can change slowly, becoming more raised and lighter in color. Some will not change at all. Some moles will slowly disappear, seeming to fade away. Others will become raised tar from the skin. They may develop a small “stalk” and eventually falloff or be rubbed off.