Pigmentary disorders are a group of conditions which affect the colour of the skin. Skin cells which produce pigment, or melanin, are called melanocytes. Increased activity or number of melanocytes results in darkening, or hyperpigmentation of the skin. Some common examples of disorders causing hyperpigmentation include freckles, solar lentigines, melasma and Hori’s naevus. Skin pigmentation disorders usually affect only a part of the skin. However, in certain conditions, they can involve the whole skin. As these disorders affect a person’s appearance, they frequently cause considerable distress and anxiety.
The five common pigmentary disorders affecting women are:
Melasma is a very common hyperpigmentary disorder that mainly occurs in women, although it can affect men in 10% of cases. This condition is characterized by the appearance of grey-brown patches on sun-exposed areas such as the cheeks,nose bridge, forehead and chin. It can also appear on other parts of the body such as the forearms and neck. Melasma is usually related to a state of hormone excess, such as in pregnancy and with use of birth control pills. In fact, it is so common in pregnancy that it has been dubbed the ‘mask of pregnancy’.
Sun exposure and tanning will make the condition worse. As such, sun protection is crucial in the treatment of melasma. This means using a broad-spectrum sunscreen every day and reapplying it frequently throughout the day. However, sun protection alone is not enough. Patients need to be seen by a dermatologist to assess how deeply the melasma has penetrated the skin. This is done using a special device called a Wood’s lamp. In some cases, a skin biopsy may be required to rule out other similar looking conditions, so that the diagnosis can be confirmed, and appropriate treatment instituted. A skin biopsy is a minor procedure involving removal of a small sample of skin which is then analysed under the microscope.
Melasma is challenging to treat as recurrence after initial successful treatment is high. It is best controlled with regular use of broad spectrum suncreens, sun protection and topical creams containing hydroquinone, azelaic acid or kojic acid, which work by lightening the skin. The dermatologist may even prescribe a combination cream containing hydroquinone, retinoid and a steroid in one. In more recalcitrant cases that do not respond to topical treatment, procedures such as intense pulse light (IPL), laser treatment, chemical peels, microdermabrasion and dermabrasion may be offered.
Melasma may fade on its own in some cases e.g. when the trigger is due to conditions such as pregnancy or taking birth control pills. Most cases of melasma can be stubborn. It may take months of treatment to see improvement. However, under the care of a dermatologist, many patients with melasma have good outcomes. It is important to follow the dermatologist’s advice closely to get the best benefit from treatment.
2) Hori’s Naevus
Hori’s nevus is a hyperpigmentary disorder more commonly seen in middle-aged Asian women. This condition consists of bluish-gray patches on the face, typically over both cheeks. The skin over the temples, eyelids, forehead and nose may also be affected. These pigmented patches usually appear in the fourth or fifth decades of life in women. Genetic and hormonal factors are likely to play a role. Melasma and Hori’s naevus can present concurrently.
As the pigmentation in Hori’s naevus penetrates very deeply into the skin, treatment is challenging. Topical creams are usually not effective. The mainstay of treatment is the use of pigment lasers to break down the melanin in the affected part of the skin. The dermatologist will decide on the most suitable modality of laser treatment, based on assessment of the patient’s skin type.
3) Solar lentigines
Solar lentiginosis is a very common hyperpigmentary disorder that affects mainly fair-skinned people over the age of 40. Commonly known as age spots or liver spots, it involves the appearance of brown, black or grey spots on sun-exposed areas of the skin. Such areas include the face, hands, arms, shoulders and upper back. The main cause of solar lentigines is sun exposure. UV rays from the sun speed up the production of melanin pigment in the skin. After years of exposure, melanin becomes concentrated in certain spots, resulting in solar lentigines. Solar lentigines are harmless and do not turn cancerous.
Although solar lentigines are harmless, other more serious skin conditions that look similar must be excluded e.g. cancerous growths. It is important to see a dermatologist, especially if the following characteristics are noted:
- very dark pigmentation or a combination of different colours
- increase in size over a short period of time
- irregular borders
- bleeding or redness
Dermatologists can diagnose solar lentigines simply by doing a thorough examination. If there are any concerns that the pigmented lesion may be something else, the dermatologist may order a skin biopsy.
Solar lentigines can be left alone as they are harmless. Some people choose to treat solar lentigines for cosmetic reasons. Treatment options include topical creams which have skin lightening properties. These medications take time to work. Procedures such as intense pulse light (IPL), pigment laser treatments, chemical peels and light cryotherapy may also be offered. Cryotherapy works by using liquid nitrogen to freeze the skin and thus destroy the melanin that is producing the pigmentation. Using pigment laser on solar lentigines can also destroy the cells producing melanin.
Freckles, known medically as Ephilides, are small flat brown marks occurring on sun-exposed areas of the skin. They can occur in both children and adults. Although they are most often seen in fair-skinned people, freckles may be inherited in some cases and can affect darker skin types. When exposed to the sun, pigment-producing cells make more melanin, which then accumulate in the surrounding skin cells. Freckles may fade as old skin cells are replaced by new ones. However, they will reappear when skin is exposed to the sun. As a person ages, freckles generally become less noticeable.
Freckles can be reduced and lightened by avoiding sun exposure and with regular use of sunscreens and skin lightening creams. Freckles can be treated with intense pulsed light (IPL) therapy or pigment laser treatment if creams and sun avoidance still do not give satisfactory results. Most patients will require about four to six treatment sessions to obtain optimal result.
5) Post-inflammatory hyperpigmentation
Post-inflammatory hyperpigmentation, or PIH for short, is a general term for excess pigment formation in the skin after an underlying skin condition has healed. Dark patches appear at the sites of the original skin lesions. This discolouration is usually temporary. However, they may become darker when exposed to sunlight. PIH can affect anyone, but is more common in darker-skinned people. In these individuals, the pigmentation tends to be more intense and persists for a longer period.
Numerous conditions can lead to PIH. Among them are:
- Skin infections
- Skin inflammation e.g. acne, psoriasis, eczema
- Skin reactions to medications
- Injury to the skin e.g. burns, abrasions
When skin is traumatized by the above conditions, an immune response occurs. This alters the activity of the pigment-producing cells, causing them to produce more melanin. As a result, there is darkening of the surrounding skin cells. Dermatologists diagnose PIH by doing a careful history and examination. In certain cases, a skin biopsy may be warranted.
Generally, PIH will gradually improve over time and normal skin colour will return. However, this is a long process that may take up to 12 months or longer. In certain cases, the dermatologist may recommend topical treatments such as hydroquinone and retinoids to lighten PIH. Procedures such as chemical peels, laser treatments and intense pulsed light may be helpful, but may also aggravate pigmentation. To reduce further darkening, patients should use sunblock or sunscreen every day and reapply frequently when outdoors.