DISCUSSION
Melasma, also known as chloasma and dubbed the “mask of pregnancy,” is an extremely common problem that results from a combination of naturally dark skin, lots of sun exposure, and increased levels of estrogenic hormones. The latter can result from pregnancy or from oral contraceptive or estrogen replacement therapy use. Another precipitating factor is thyroid disease, certain types of which lead to an increase in melanocytic stimulating hormone.
Melasma, as one might expect, is seen almost exclusively in women, though a rare male is affected. It is especially common among Latina, Native American, and African-American women, whose melanocytes are especially able to produce pigment.
There are several treatments for melasma, none of them perfect, including tretinoin, azelaic acid, chemical peels, dermabrasion, and lasers. The most common treatment is hydroquinone cream, available in the US in both OTC (2%) and prescription (4%) strengths. However, hydroquinone is available OTC in stronger formulations (15% to 20%) in many Central and South American countries; unfortunately, many women who obtain and use these products experience exogenous ochronosis—a worsening or even precipitation of melasma, resulting from excessive production of tyrosinase.
Any treatment must be used in conjunction with rigorous sunscreen application. A full-spectrum product, with titanium dioxide and zinc oxide as the only active ingredients, must be used, because chemical-laden sunscreens don’t do as good a job covering UVA, UVB, and visible light. Convincing women who are unaccustomed to needing sunscreen to use it religiously is part of what makes treating melasma difficult.
The differential for melasma includes postinflammatory hyperpigmentation (eg, following an episode of contact dermatitis) and simple solar lentigines.
This patient was treated with hydroquinone 4% cream bid, plus sunscreen. She was also given information about other treatment options, such as laser and dermabrasion.
TAKE-HOME LEARNING POINTS
- Melasma, also known at chloasma, is quite common, especially among women with darker skin who live in sunny parts of the world.
- It results from a combination of dark skin, an increased level of estrogenic hormones (eg, with pregnancy, birth control pills, or estrogen replacement therapy), and excessive exposure to UV light.
- While hydroquinone cream can be an effective treatment, the maximum strength should be 4%; overuse of stronger concentrations (available in other countries, such as Mexico), can actually cause melasma to worsen.