Melasma is an alteration of the skin characterized by chronic acquired hypermelanosis and the term comes from the Greek word "melas", which means black. In fact, this condition is manifested by the presence of dark pigmented skin spots. They are spread over areas of the body exposed to the ultraviolet rays of the sun, since this is a photosensitive type of hyperpigmentation. Therefore, the most affected areas are the face, neck and arms.
Since they spread symmetrically, these spots are characterized by irregular edges and a color that varies from brown to grey. On the skin, this discoloration has a considerable psychological impact on the quality of life of the people affected. The dark spots on the face can affect the forehead, cheeks, temples and upper lip.
This condition affects millions of people around the world, although melasma predominantly affects women of reproductive age. This aesthetic problem affects all racial groups, although it is more common in more pigmented phenotypes (Fitzpatrick III-V).
Many recent studies have shown that melasma is strongly influenced by estrogen secretion. However, there are still many doubts about its pathogenesis and etiology. In any case, this hypermelanosis is obviously triggered and worsened by the following:
- exposure to intense sun
- sex hormones
- hormone therapy, particularly with oral contraceptives
- inflammation of the skin
- use of cosmetics, steroids and photosensitizing drugs
Among the etiological factors there is also a clear connection with genetic predisposition.
The influence of UV rays is evident during the summer months because the spots tend to become more pronounced, unlike what happens in the winter months.
One hypothesis suggests that the spots originate due to the presence of melanocytes more biologically active in areas with melasma compared to areas without spots. Following UV exposure, melanocytes produce more melanin than the uninvolved skin. Recent studies suggest that there is an interaction between cutaneous vascularization and melanocytes in the development of this hyperpigmentation.