Hyperpigmentation

Hyperpigmentation is the darkening of an area of skin or nails caused by increased melanin production as a result of sun damage, inflammation or skin injuries. Hyperpigmentation is associated with a significant number of conditions and is more common in people with darker skin tones.

Hyperpigmentation can be caused by sun damage, inflammation, or other skin injuries, including those related to acne vulgaris. People with darker skin tones are more prone to hyperpigmentation, especially with excess sun exposure.

Many forms of hyperpigmentation are caused by an excess production of melanin. Hyperpigmentation can be diffuse or focal, affecting such areas as the face and the back of the hands. Melanin is produced by melanocytes at the lower layer of the epidermis. Melanin is a class of pigment responsible for producing color in the body in places such as the eyes, skin, and hair. The process of melanin synthesis (melanogenesis) starts with the oxidation of l-tyrosine to l-dopa by the enzyme tyrosine hydroxylase, then to l-dopaquinone and dopachrome, which forms melanin.

As the body ages, melanocyte distribution becomes less diffuse and its regulation less controlled by the body. UV light stimulates melanocyte activity, and where concentration of the cells is greater, hyperpigmentation occurs. Another form of hyperpigmentation is post-inflammatory hyperpigmentation. These are dark and discoloured spots that appear on the skin following acne that has healed.

Hyperpigmentation is associated with a number of diseases or conditions, including the following:

Hyperpigmentation can sometimes be induced by dermatological laser procedures.

There are a wide range of depigmenting treatments used for hyperpigmentation conditions, and responses to most are variable.

Most often treatment of hyperpigmentation caused by melanin overproduction (such as melasma, acne scarring, liver spots) includes the use of topical depigmenting agents, which vary in their efficacy and safety, as well as in prescription rules.