Skin pigmentation is most common in women, with about 10% of cases reported in men. It affects people of any race but is more prominent among Asians and Latinos, those living in areas of high UV light exposure.

Clinically speaking, pigmentation can be divided into three patterns. In centrofacial pattern, the pigmentation occurs on the cheeks, forehead, upper lip, nose and chin. In malar pattern the patches appear on the cheeks and nose, while in mandibular pattern they show on the side of the cheeks and jaw line.

Types of pigmentation include epidermal pigmentation where the pigmentation resides in the epidermis layer of the skin, dermal pigmentation where the pigmentation is located in the dermis layer, and mixed pigmentation, a mixture of epidermal and dermal types. Epidermal pigmentation is the most common type and relatively more responsive to treatments.

Causes of Pigmentation

There are a number of factors that contribute to the development of pigmentation, with sun exposure being the major one. Other factors include hormonal changes such as during pregnancy and the use of oral contraceptives, as well as endocrine disorders such as thyroid or ovarian dysfunction, which are further aggravated by sun exposure.

The use of phototoxic cosmetics containing mercury and salicylic acids may increase the skin's sensitivity to sunlight, leading to the development of pigmentation. Long term use of phototoxic medication including antibiotics, anti-epilepsy drugs, and nonsteroidal anti-inflammatory drugs may also contribute to the appearance of pigmentation.

Melasma vs Freckles

There are some differences between melasma and freckles. Melasma is acquired, which means that it is gotten due to environmental factors, while freckles are hereditary. Melasma is more common in people with brownish skin tones, such as Asians and Latinos. Freckles are more common in fair skinned people such as Europeans. Melasma develops in adulthood, whereas freckles in childhood through adulthood.

Melasma appears as brown or grey-brown patches, while freckles are in the form of spots that can be red, yellow, tan or brown. There are centrofacial, malar and mandibular patterns of melasma, whereas freckles typically appear on the cheeks around the eyes and across the bridge of the nose.

Freckles
Melasma

Although they are basically different, melasma and freckles share one thing in common: they are worsened by sun exposure.

Sun exposure

Animation shows the effects of UV rays from the sun affecting the skin

Exposure to the sun is the main factor contributing to the development of pigmentation. As the most outer organ of our body, our skin is frequently and directly exposed to the sun's UV radiation that generates harmful free radicals and triggers inflammation, increasing the number of melanocytes (melanin-producing cells) and stimulating their activity in producing melanin. This eventually leads to an excessive production of melanin, resulting in the appearance of unsightly dark spots and brown patches.

The production of melanin is a complex oxidation process involving the enzyme tyrosinase that converts the amino acid tyrosine into melanin.