What Causes Age Spots All Over the Legs & Arms?

Age spots occur when melanin, the substance that gives your skin its color, is produced in excess in a specific area of the skin. This causes melanin to clump together, giving the appearance of a brown spot. Age spots are more common after the age of 40, but can develop at any time. Age spots, also called sun spots and liver spots, typically form on areas of the skin not regularly covered by clothing, especially the arms, hands and legs.

Sun Exposure

Sun is one possible key component in age spot formation. According to the Mayo Clinic, exposure to the sun's ultraviolet radiation increases the production of melanin in the skin, which can contribute to the formation of sun spots. Because the arms and legs are often uncovered during the summer due to the heat, they are more prone to age spot formation.

Tanning Bed

Like spending time in the sun, spending time in tanning beds or booths can also contribute to age spot formation. Although tanning beds produce less harmful ultraviolet radiation than the sun, they still provide enough to increase the production of melanin in the skin, according to the Health Physics Society. This can lead to spots of irregular melanin production, creating one or more sun spots on exposed skin tissue.

Skin Tone

The color of your skin can also contribute to age spot formation. Those with darker skin naturally have more melanin in the skin tissue, reducing the risks for spot formation. However, the Mayo Clinic suggests that having light or fair skin puts you at a higher risk for developing age spots, which are also more noticeable on fair skin than on those with a darker skin complexion.

Cancer Risks

According to the American Academy of Dermatology, some spots on the skin may look like age spots, but they are actually actinic keratosis. Some cases of actinic keratosis, if left untreated, can progress into skin cancer.

As with any unusual spot or mole on the skin, you should have your doctor or dermatologist check the area to insure that it is not cancerous or pre-cancerous. Only a trained eye can make the final decision on whether the mark is truly an age spot or a potential health danger.