Find possible causes of numbness or tingling in hands based on specific factors. Check one or more factors on this page that apply to your symptom. Numbness or tingling. 1  Affects both hands. 2  Affects one hand.  Is intermittent.
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. Darker areas of skin (or an area that tans more easily) occurs when you have more melanin or overactive melanocytes. Bronzing of the skin may sometimes be mistaken for a suntan.
Melanoma occurs when something goes awry in the melanin-producing cells (melanocytes) that give color to your skin. Normally, skin cells develop in a controlled and orderly way â healthy new cells push older cells toward your skin's surface, where they die and eventually fall off. But when some cells develop DNA damage, new cells may begin to grow out of control and can eventually form a mass of cancerous cells. Just what damages DNA in skin cells and how this leads to melanoma isn't clear. It's likely that a combination of factors, including environmental and genetic factors, causes melanoma. Still, doctors believe exposure to ultraviolet (UV) radiation from the sun and from tanning lamps and beds is the leading cause of melanoma. UV light doesn't cause all melanomas, especially those that occur in places on your body that don't receive exposure to sunlight.