Elderly people sometimes develop what are known as liver spots, which are darker areas or blemishes on their skin. Why, and what causes them?
• Tissues such as hair and skin do not produce their own colour; they get that from neighbouring cells called melanocytes through a remarkable process that involves injection of the pigment raw material, melanin, into the cells of the growing tissue.
Fresh melanin is practically colourless, gaining its final colour as the new tissue matures. Even after that, sunlight may cause it to darken further, which is the temporary tanning effect we see in our skins after unaccustomed exposure to strong sunlight.
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People, particularly those with certain genetic make-up and who have exposed themselves to a lot of ultraviolet light as they aged, may find some of their melanocytes multiplying or darkening, or both, forming visible patches in the skin tissue. The resulting effect is known as freckles, , or depending on the details.
Unlike most similar-looking medically important growths, the typical liver spot is flat, harmless and requires no treatment unless for cosmetic purposes.
A medical checkup every year or two, in case a patch is hiding or developing into something more serious, is not a bad idea, but generally liver spots are of little medical interest except to dermatologists.
Jon Richfield, Somerset West, South Africa