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Melasma (also known as Chloasma faciei,:854 or the mask of pregnancy when present in pregnant women) is a tan or dark skin discoloration. Although it can affect anyone, melasma is particularly common in women, especially pregnant women and those who are taking oral or patch contraceptives or hormone replacement therapy (HRT) medications. It is also prevalent in men and women of Native American descent (on the forearms) and in men and women of German, Russian, and Jewish descent (on the face).
The symptoms of melasma are dark, irregular well demarcated hyperpigmented macules to patches commonly found on the upper cheek, nose, lips, upper lip, and forehead. These patches often develop gradually over time. Melasma does not cause any other symptoms beyond the cosmetic discoloration. Melasma is also common in pre-menopausal women. It is thought to be enhanced by surges in certain hormones
Melasma is thought to be the stimulation of melanocytes or pigment-producing cells by the female sex hormones estrogen and progesterone to produce more melanin pigments when the skin is exposed to sun. Women with a light brown skin type who are living in regions with intense sun exposure are particularly susceptible to developing this condition.
Genetic predisposition is also a major factor in determining whether someone will develop melasma.
The incidence of melasma also increases in patients with thyroid disease. It is thought that the overproduction of melanocyte-stimulating hormone (MSH) brought on by stress can cause outbreaks of this condition. Other rare causes of melasma include allergic reaction to medications and cosmetics.
Melasma Suprarenale (Latin - above the kidneys) is a symptom of Addison's disease, particularly when caused by pressure or minor injury to the skin, as discovered by Dr. FJJ Schmidt of Rotterdam in 1859.
Differential diagnosis 
- Post inflammatory hyperpigmentation
- Actinic lichen planus
The discoloration usually disappears spontaneously over a period of several months after giving birth or stopping the oral contraceptives or hormone replacement therapy.
Treatments are often ineffective as it comes back with continued exposure to the sun. Treatments to hasten the fading of the discolored patches include:
- Topical depigmenting agents, such as hydroquinone (HQ) either in over-the-counter (2%) or prescription (4%) strength. HQ is a chemical that inhibits tyrosinase, an enzyme involved in the production of melanin.
- Tretinoin, an acid that increases skin cell (keratinocyte) turnover. This treatment cannot be used during pregnancy.
- Azelaic acid (20%), thought to decrease the activity of melanocytes.
- Chemical peels.
- Microdermabrasion to dermabrasion (light to deep).
- Galvanic or ultrasound facials with a combination of a topical crème/gel. Either in an æsthetician's office or as a home massager unit.
- Laser treatment. A Wood's lamp test should be used to determine whether the melasma is epidermal or dermal. Dermal melasma often proves difficult to treat, and has only been found to lighten with products containing mandelic acid (such as Triluma cream) Profractional (Sciton) or Fraxel laser or laser phototherapy (Intense pulsed light ).
In all of these treatments the effects are gradual and a strict avoidance of sunlight is required. The use of broad-spectrum sunscreens with physical blockers, such as titanium dioxide and zinc dioxide is preferred over that with only chemical blockers. This is because UV-A, UV-B and visible lights are all capable of stimulating pigment production.
Cosmetic camouflage can also be used to hide melasma.
See also 
- Gineblog - El cloasma o melasma. In Spanish.
- James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0-7216-2921-0.
- Tunzi M, Gray GR (January 2007). "Common skin conditions during pregnancy". Am Fam Physician 75 (2): 211–8. PMID 17263216.
- G Zoccali, D Piccolo, P Allegra, M Giuliani (March 2010). "Melasma Treated with Intense Pulsed Light". Aesthetic Plastic Surgery 34 (4): 486–93. doi:10.1007/s00266-010-9485-y. PMID 20225000.
- Melasma Treatment Options - Melasma Treatment
- DermNet colour/melasma
- Health In Plain English - Melasma or Chloasma
- MSM for Melasma - Megadoses of sulphur helps some sufferers