A 25-year-old Hispanic woman presents to the dermatology clinic in the spring with a symmetrical brown hypermelanosis on the cheeks, forehead, nose and chin. The macular lesions have serrated, irregular and geographic borders.
History reveals no other symptoms, but the patient reports spending time outside gardening. What’s your diagnosis?
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Melasma is an acquired hypermelanosis that occurs in sun-exposed areas and is most common among women of childbearing age. The disorder occurs in all races, but is particularly prominent among Hispanics and Asians.
Melasma is typically exacerbated by sun exposure, pregnancy, oral contraceptive use and certain anti-epilepsy drugs, but can also arise from other factors, including endocrine dysfunction, genetic factors, nutritional deficiency and hepatic dysfunction. About a third of cases are idiopathic.
Patients with melasma present with symmetrical hyperpigmented macules, most often in three distinct facial patterns: centrofacial, involving the cheeks, upper lip, nose and chin; malar pattern, involving the cheeks and nose; and the mandibular patter, involving the ramus of the mandible. Although the skin condition is most common on the face, it can occur, albeit rarely, in other sun-exposed areas such as the forearms.
A patient’s clinical features alone usually establish diagnosis, but clinicians can use a Wood’s lamp to distinguish between epidermal and dermal hyperpigmentation. The color of the hyperpigmentation can also help clinicians determine which form of hypermelanosis a patient has, with brown indicating epidermal forms, blue-gray indicating dermal forms, and brown-gray indicating a mixed form of the condition.
Clinical course and prognosis
Melasma is a chronic disorder exacerbated by sunlight, as well as artificial UVA and UVB. Women may experience varied degrees of melasma during the course of several pregnancies, but the disorder may slowly resolve after childbirth or after oral contraceptives are discontinued.
Aside from skin discoloration, melasma does not cause any other symptoms, so treatment is primarily cosmetic in nature.
Epidermal melasma can be treated with a combination of sunscreen and bleach. Sun avoidance or use of a broad-spectrum opaque sunscreen that has an SPF >30, even when indoors, are necessary for successful treatment.
Skin bleaching creams and gels should contain 2% to 4% hydroquinone solution. Clinicians should be aware that higher concentrations carry an increased risk of contact irritation. Topical tretinoin gel may also be used simultaneously. The only topical cream currently FDA-approved for melasma is Triple Combination Cream, a composite of hydroquinone (4%), tretinoin (0.05%) and fluocinolone acetonide (0.01%). Adverse events are usually mild, involving skin irritation, particularly when higher concentrations are used.
Alternatives include azelaic acid in a 20% cream-based formulation or exfoliating superficial chemical peels. Other treatment options, including cryotherapy, medium-depth chemical peels and laser therapy yield unpredictable results and can result in a range of adverse events including epidermal necrosis, post inflammatory hyperpigmentation and hypertrophic scars.
Symptom resolution is gradual and may take as many as six months to complete the process. Resistant or recurrent melasma is common if patients do not adhere strictly to sun avoidance.
Patients taking oral contraceptives may not respond to treatment unless they discontinue birth control, and patients who are pregnant or breastfeeding should not be treated. Cases of exogenous ochronosis have been reported after prolonged treatment with higher concentrations of hydroquinone.
1. Freedberg IM, Isin AZ, Wolff K, et al. Fitzpatrick’s Dermatology in General Medicine (5th ed.). 1999. New York: McGraw-Hill.
2. Sood A, Tomecki KJ. Pigmentary disorders. In: Carey WD, ed. Cleveland Clinic: Current Clinical Medicine 2010. 2nd ed. 2010: Philadelphia, Pa: Saunders Elsevier.