Age, sun or liver spots (Solar Lentigines) and freckles (Ephelides) are tan, brown, ashengrey (on people with darker skin tones) or black spots that generally appear on the backs of the hand, face and body. They are caused by prolonged or repeated sun
exposure or burns and often grow with time.

Brown or ashen patches of skin (chloasma or melasma) can also occur from birth control pills, anti-epilepsy drugs, pregnancy (linea nigra and pregnancy mask), or hormone replacement therapy (hormone masking). Other health-related problems can be possible causes. It is recommended that you should consult with your doctor should your skin undergo sudden or unexpected changes in colour.

Regardless of the cause, this hyperpigmentation on the skin is formed by areas of increased melanin production (responsible for skin pigment and tanning) and melanin
that has accumulated within the top layer of skin (epidermis). Melanin is created by melanin synthesis, a complex process partially controlled by an enzyme called tyrosinase.