Melasma is a common pigmentary disorder that affects women more than men. It is also known as chloasma or the mask of pregnancy. Women of Hispanic and Asian origin get this disorder commonly starting at puberty or later. Darkly pigmented races from India, Pakistan, and the Middle East can develop this disorder during the first decade of life.
Melasma CauseThe exact cause of melasma is unknown, but several factors that contribute to the development of the rash.
- Genetic predisposition
- UV light exposure
- Oral contraceptive use
- Hormonal changes in pregnancy
- Drugs that sensitize the skin to UV radiation
Melasma Clinical PatternsThere are three types of melasma, based on the distribution of the rash on the face. These patterns do not predict response to medications, but they do predict how the rash may spread. The three types are:
- Centrofacial -- Occurs in two-thirds of melasma patients on the forehead, nose, chin, and central cheeks.
- Malar -- Occurs in about twenty percent of cases on the cheeks and nose.
- Mandibular -- Occurs in about fifteen percent of cases on the jawline.
Melasma Cellular PatternsThere are four types of melasma based on Wood's (ultraviolet) light examination which shows the depth of the pigmentation. These cellular patterns help determine whether the rash will respond better to medications or laser. The four cellular types are:
- Epidermal -- The most common type shows enhancement of the color contrast between normal and affected skin.
- Dermal -- Does not show enhancement of the color contrast between normal and affected skin.
- Mixed Epidermal and Dermal -- Shows enhancement of the color contrast between some of the affected skin but not others.
- Inapparent -- Seen in very dark-skinned people, affected lesions are not seen under Wood's light.
Melasma TreatmentMelasma is difficult to treat, but a significant factor in treatment is limiting exposure to UV radiation. The use of a broad spectrum sunscreen that blocks UVA and UVB is essential. The epidermal type responds to depigmenting agents but the dermal type does not. The most common depigmenting agent is hydroquinone which can be found over the counter in 2-percent strength and by prescription in 4-percent strength. Hydroquinone works by turning off the cells that make melanin. Retin-A and azelaic acid may be used alone or in combination with hydroquinone to reduce epidermal pigment, but they should not be used in pregnancy. Chemical peels may be considered in lighter-complexioned patients only because the peel can cause a reactive hyperpigmentation in darker-complexioned patients. Combination laser treatments have been reported to be effective for the dermal type of melasma.
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Gupta, Aditya, et al. "The treatment of melasma: A review of clinical trials." Journal of the American Academy of Dermatology. 55 (2006): 1048-1065.
Habif, Thomas. "Melasma." Clinical Dermatology, 4th Edition. Ed. Thomas Habif, MD. New York: Mosby, 2004. 692-3.