Skin - abnormally dark or light. Skin that has turned darker or lighter than normal is usually not a sign of a serious medical condition. Normal skin contains cells called melanocytes. These cells produce melanin, the substance that gives skin its color. Skin with too much melanin is called hyperpigmented skin. Skin with too little melanin is called hypopigmented skin. Pale skin areas are due to too little melanin or underactive melanocytes.