The origin of pigmented spots.

Pigment spots are caused by a disruption in the pigmentation process (melanogenesis). The melanin, pigment responsible for the natural colouration of the skin, is overproduced in certain areas, leading to the appearance of brown, red or pink spots. These spots most often appear on the face. However, they can manifest anywhere on the body, particularly on the forearms, décolletage, upper back, backs of the hands, and shoulders. They can affect all skin tones and types. Nevertheless, they appear more frequently in individuals over the age of 40 and in those with darker phototypes (IV to VI).

Brown spots are generally harmless, but for safety, it is important to monitor them. Indeed, if they change in shape, colour, size or if they start to itch or bleed, it is essential to consult a dermatologist.

Depending on their origins, pigmented spots are classified into several categories:

• Sun spots (lentigo or age spots), caused by prolonged and repeated exposure to the sun's UV rays.

  As a reminder, the production of melanin by melanocytes increases under the influence of UV rays and pigmentary anomalies can occur. They primarily appear on the most frequently exposed parts of the body. Be aware, the intake of certain photosensitising medications can promote lentigines. Furthermore, lentigo can also be caused by the skin ageing. With age, the skin fails to fully protect itself from external aggressions and deteriorates. A dysfunction of melanocytes is observed, associated with the exhaustion of their pigmentary potential at the level of hair follicles. This phenomenon is attributed to the consequences of repeated attacks of reactive oxygen species (or free radicals) on the nuclei of melanocytes and mitochondria. When this happens, the skin becomes vulnerable to UV rays, responsible for pigment spots then called "age spots". To prevent this, at any age, it is therefore essential to apply a sun protection suitable for your skin tone before sun exposure.

• Melasma, pigmentation spots caused by hormonal fluctuations.

  Also referred to as chloasma or melasma, these hyperpigmentation marks are caused by hormonal changes. They occur during pregnancy but also following the use of contraceptive pills or hormone replacement therapy. Indeed, hormones stimulate melanocytes, thus causing an overproduction of melanin. It should be noted, the pregnancy mask generally disappears after childbirth, although this may take some time.

• Thepost-inflammatory hyperpigmentation.

  These pigmented spots are the result of increased activity of melanocytes, stimulated by pro-inflammatory cytokines following inflammation (injuries, burns, blemishes, acne flare-ups). This type of marking is more common in individuals with medium to dark skin phototypes.

Note : Pigment spots can also be ofgenetic origin like freckles, which appear at the time of birth. This phenomenon, usually associated with fair skin, poses no danger to the body.

• DE LA FUENTE J. Cosmetic Management of Skin Hyperpigmentation (2017).

• SFD Laser Group. Pigmented Spots (2017).