Both internal factors (genetics, hormones, etc.) and external factors (sun radiation, tattoos, diet, medicinal products, etc.) have an influence on the hyperpigmentation of the skin. In the epidermis, more specifically in the basal layer, there are star-shaped cells (melanocytes) producing a pigment called melanin. It is mainly this melanin that "colours" the skin and hair. The differences in terms of quantity and location of melanin in the various epidermal layers explain the different skin phototypes.
Dark patches on the skin
The appearance of patches on the skin is related to the production of melanin.
This melanin production is often not homogeneous and is distributed or synthesised abnormally. This disorder can lead to pigment accumulation in some areas, known as dark spots. For instance, sun exposure stimulates the appearance of sun lentigines and freckles or ephelides, and a hormonal imbalance, such as what occurs during pregnancy or with the use of anovulants, can enhance the appearance of melasma or chloasma. Melasma (or chloasma, the mask of pregnancy) is a brown coloured pigmentation located on the face (forehead, lips, cheeks) with ill-defined edges, much more common in women, which sometimes appear unrelated to pregnancy or contraceptive treatments.
How do the patches occur?
The skin patches occur as a consequence of an abnormal synthesis of melanin.
Melanin is a set of pigments produced in the melanocytes, which are cells located in the basal layer of the epidermis.
There are two types of melanin: eumelanin (dark colour, black) and pheomelanin (reddish brown colour, blond). Mixtures of the two determine the skin and hair colour. In addition to defining the skin colour, melanin protects us against sun radiation through its filtering action.
When melanin is produced progressively and evenly, it is called tanning, but when it is distributed or synthesised abnormally, patches appear on the skin, such as lentigines or melasma.
Treating skin blemishes
The treatment of skin blemishes should be approached from a multifactorial perspective.
The best recommendation to prevent the appearance of skin blemishes is to avoid sun exposure as much as possible, as sunlight causes them to become even darker.
In cases where blemishes have already appeared, it is necessary to establish how to try to remove them.
The application of depigmenting action products (with active ingredients that act on the synthesis of melanin, such as kojic acid, arbutin or curcumin), together with sunscreen, form the basis of the treatment to eliminate or reduce existing blemishes.
Exfoliating products are also useful, which exert a corrective action, since they speed up the renewal of the skin and, therefore, favour the elimination of accumulated pigment.
The depigmenting treatment requires a lot of perseverance and patience, since its effects are not immediate. It is normally necessary to apply the products for a minimum of 3 months in order to obtain results.
In the case of melasma or post-inflammatory hyperpigmentation, it may be necessary to resort to medications with a depigmenting effect, such as hydroquinone, which must be prescribed by the dermatologist.