What is Melasma?

Melasma (also known as chloasma) is a skin condition in which brown patches occur primarily on the cheekbones, forehead and upper lip. It also may develop on the nose chin, lower cheeks and sides of the neck. The dark patches usually have distinct edges. Melasma is seen most frequently in young women taking birth control pills and also occurs commonly during pregnancy. It may develop in association with menopause, hormonal imbalance and ovarian disorders. Melasma may also be triggered by a medication called Dilantin (phenytoin). In many cases, it occurs without any of these predisposing factors and is occasionally seen in men. The keys to melasma prevention and treatment are sun avoidance/protection and skin lightening products. The tendency to develop melasma is genetically predetermined. Most of the genetic factors that contribute to this tendency are not yet understood, but it is clear that persons who have inherited baseline skin color in the very light olive to very dark olive range are particularly susceptible.

Melasma has been referred to as the mask of pregnancy because it often develops during pregnancy. Because of melasma's relation to pregnancy and oral contraceptives, it is thought that estrogen contributes to its development in predisposed persons. Estrogen is not essential to the development of melasma, however, as men may also be affected. A factor that does seem to be essential to the development of melasma is sunlight. Both ultraviolet A (UVA) and ultraviolet B (UVB) are believed to contribute to the formation of melasma in predisposed persons. The pigmentation of melasma may be deposited in one or more layers of the skin. The pigment may be confined to the surface layer of skin, the epidermis. Alternatively, it may be present solely in the inner layer of skin, the dermis.

Generally, however, it is present to a greater or lesser degree in both outer layers of skin. The presence of pigmentation both within the skin's surface layer as well as deeper within the skin has important implications for melasma treatment. Melasma develops due to a combination of genetic, hormonal and sun related factors. In order to prevent melasma, this combination has to be altered. It is impossible to change the genetic tendency towards melasma and often not practical to alter hormonal influences.

Thus the mainstay of melasma prevention is complete sun protection including regular use of broad-spectrum sunscreens and sun protective hats and clothing as well as avoidance of sun within practical limits. The treatment of existing melasma is based upon this idea of total sun protection as well as the use of products designed to decrease pigmentation within the surface skin layer. Dermatologists typically recommend sunscreen every morning, hydroquinone containing skin bleaches at bedtime or twice daily and vitamin A derivatives nightly as tolerated for persons with melasma. This regimen generally provides visible results within a couple months and optimal results within six months. All sunscreens are over the counter and milder skin bleaches and vitamin A products are also available over the counter. More potent and potentially irritating bleaches and vitamin A derivatives are available by prescription. Dermatologists also may recommend on a case by case basis chemical peeling with either glycolic or tri-chloro-acetic (TCA) acid to speed improvement of melasma. Microdermabrasion has also been found to be helpful in the treatment of melasma especially when used in concert with topical products.

Regardless of the methods used to treat melasma, results vary greatly. Much of this variation is because of differences in where the melasma related pigmentation is located within the skin in different people. Surface pigmentation is relatively easily removed by standard treatments but deeper pigmentation does not respond to surface treatment. Deeper pigmentation does, however, tend to slowly fade away over months to years if there is complete and consistent sun protection. People with primarily surface pigmentation can expect to see more rapid and dramatic results from treatment than those with primarily deeper pigmentation. One day of unprotected sun exposure in a person prone to melasma can undo months of treatment, especially in those with a tendency towards deeper pigmentation.

Melasma is a challenge to successfully treat and requires great discipline with regards to continuous sun protection. Fortunately, most people can obtain satisfying results with a combination of sunscreen/avoidance and appropriate topical treatments. Background: Melasma is an acquired hypermelanosis of sun-exposed areas. It presents as symmetrical hyperpigmented macules, which can be confluent or punctate. The cheeks, upper lip, chin, and forehead are the most common locations, but it can occasionally occur in other sun-exposed locations. Chloasma is a synonymous term sometimes used to describe the occurrence of melasma during pregnancy. Chloasma is derived from the Greek word chloazein, meaning "to be green." Melas, also Greek, means "black." Since the pigmentation is never green in appearance, melasma is the preferred term. It is much more common in women than in men, and in constitutionally darker skin types than in lighter skin types. In some cases there appears to be a direct relationship with female hormonal activity, since it occurs with pregnancy and with the use of oral contraceptive pills.

Other factors implicated in the etiopathogenesis of melasma are photosensitizing medications, mild ovarian or thyroid dysfunction, and certain cosmetics. The most important factor in the development of melasma is exposure to sunlight. Without the strict avoidance of sunlight, potentially successful treatments for melasma are doomed to failure. All races are affected, but it may be more common in light brown skin types, especially Hispanics and Asians, from areas of the world with intense sun exposure. Women are affected in 90% of cases. When men are affected, the clinical and histologic picture is identical. Melasma is rare before puberty and occurs most commonly in women during their reproductive years.

Patients may inquire about progressive hyperpigmentation of the face, which may be temporally related to pregnancy or to the use of oral contraceptive pills. Intense or chronic exposure to sunlight will worsen the condition and may precipitate melasma, but because the development of pigmentation is often insidious, patients may not recognize the association. The macular hyperpigmentation of melasma is tan-brown in color and occurs in 1 of 3 patterns: centrofacial, malar and mandibular. In addition, the excess melanin can be visually localized to the epidermis or dermis by use of a Wood lamp (wavelength 340-400 nm). Epidermal pigmentation is enhanced during examination with Wood's light, whereas, dermal pigment is not. Clinically, a large amount of dermal melanin will be suspected if the hyperpigmentation is bluish-black in appearance. In individuals with dark brown skin, examination with Wood's light will be unable to localize pigment and these patients are thus classified as indeterminate. Dermal pigmentation may take longer to resolve than epidermal pigmentation since there is no effective therapy capable of removing dermal pigmentation.

However, treatment should not be withheld simply because of a preponderance of dermal pigmentation. The source of the dermal pigmentation is the epidermis, and if epidermal melanogenesis can be inhibited for long enough periods of time, the dermal pigmentation will not replenish and will slowly resolve. A genetic predisposition is a major factor in the development of melasma. It is found much more commonly in women than in men. Light brown skin types from regions of the world with intense sun exposure are much more prone to the development of melasma. More than 30% of patients will have a family history of melasma. Identical twins have been reported to develop melasma, while other siblings under similar conditions did not. Another major factor is exposure to sunlight. Ultraviolet radiation can cause peroxidation of lipids in cellular membranes, leading to generation of free radicals, which could stimulate melanocytes to produce excess melanin. Sunscreens that block primarily ultraviolet-B radiation (290-320 nm) are unsatisfactory because longer wavelengths (ultraviolet-A and visible radiation, 320-700 nm) will also stimulate melanocytes to produce melanin.

Hormonal influences play a role in some individuals. The mask of pregnancy is well known to obstetrical patients. The exact mechanism by which pregnancy affects melasma is unknown. Estrogen, progesterone, and melanocyte-stimulating hormone (MSH) are normally increased during the third trimester of pregnancy. However, nulliparous patients with melasma have no increased levels of estrogen or MSH. In addition, the occurrence of melasma with estrogen- and progesterone-containing oral contraceptive pills and diethylstilbestrol treatment for prostate cancer has been reported. One study found a 4-fold increase in thyroid disease in patients with melasma when compared to matched controls. A case report of two women who developed melasma after sudden and profound emotional stress implicated the release of MSH by the hypothalamus as a cause. Exactly which hormones and what mechanisms are involved in the development of melasma are yet to be determined. Genetic and hormonal influences in combination with ultraviolet radiation are the two most important causes of melasma, yet phototoxic and photoallergic medications and certain cosmetics have been reported to cause melasma in rare instances.
(information resources include....www.reddingdermatology.com and www.emedicine.com)