Melasma and Solar Lentigines: How to Differentiate?

Also known as "chloasma", the melasma is due to hormonal fluctuations. Women with darker skin types and/or who are pregnant are more likely to develop melasma. The increase in oestrogen levels, particularly during pregnancy or with the use of certain medications (e.g.: contraceptive pill), can lead to brown spots. These are exacerbated by exposure to the sun's UV rays. This hyperpigmentation phenomenon is also known as the "mask of pregnancy". It often disappears spontaneously after childbirth. However, it's important to note that melasma does not only affect women. According to the American Academy of Dermatology, only 10% of melasma cases affect men.

Lentigo, for its part, affects both men and women. It is also referred to as solar spots or age spots. These brown spots are due to prolonged and repeated exposure to the sun's UV rays. As a reminder, the production of melanin by melanocytes increases under the action of UV rays and pigment abnormalities can occur. They mainly appear on the most frequently exposed parts of the body. Be aware, the use of certain photosensitising medications can promote lentigos. Moreover, lentigo is also due to skin ageing. With age, the skin is unable to fully protect itself from external aggressions and deteriorates. A dysfunction of the melanocytes is observed, associated with the exhaustion of their pigment potential at the level of the 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 type before sun exposure.

The appearance of these brown spots is different.

• The melasma takes the form of extended spots, which form a kind of mask on the surface of the epidermis, usually symmetrical between the two sides of the face. Depending on the location of the brown spots, there are in fact three types of melasma: the centrofacial melasma (spots grouped in the T-zone, upper lip and chin), the malar melasma (spots only on the nose and cheeks), the mandibular melasma (spots on the lower jaw). Melasma only appears on the face.

• Sun spots typically have well-defined edges, as well as a rounded and flat shape. Unlike melasma spots, they do not only appear on the face but are also present in numbers on the backs of the hands, the décolletage, the shoulders and the back, which are the areas frequently exposed to the sun's UV rays.