Hyperpigmentation

Melasma consists of dark brown, roughly symmetric patches of hyperpigmentation with irregular borders on the face (usually on the forehead, temples, cheeks, cutaneous upper lip, or nose). It occurs primarily in pregnant women (melasma gravidarum, also called the mask of pregnancy) and in women taking oral contraceptives. Ten percent of cases occur in nonpregnant women and dark-skinned men. Melasma is more prevalent among and lasts longer in people with dark skin.

Melasma

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DR P. MARAZZI/SCIENCE PHOTO LIBRARY

Because melasma risk increases with increasing sun exposure, the mechanism probably involves overproduction of melanin by hyperfunctional melanocytes. Other than sun exposure, aggravating factors include

• Autoimmune thyroid disorders

• Photosensitizing drugs

In women, melasma fades slowly and incompletely after childbirth or cessation of hormone use. In men, melasma rarely fades.

Polypodium leucotomas can enhance protection (1, 2). Because of potential health and environmental toxicities, oxybenzone and benzophenone-3 are usually not preferred sunscreens (3).

Other treatment depends on whether the pigmentation is epidermal or dermal; epidermal pigmentation becomes accentuated with a Wood light (365 nm) or can be diagnosed with biopsy. Only epidermal pigmentation responds to treatment. Most topical melasma treatments are used in combination rather than individually.

Triple topical therapy is first-line treatment that is often effective and consists of a combination of

• A class V to VII topical corticosteroid ( see Table: Relative Potency of Selected Topical Corticosteroids)

4).

Lentigines (singular: lentigo) are flat, tan to brown, oval macules. They are commonly due to chronic sun exposure (solar lentigines; sometimes called liver spots but are not related to hepatic dysfunction) and occur most frequently on the face and back of the hands. They typically first appear during middle age and increase in number with age. Although progression from lentigines to melanoma has not been established, lentigines are an independent risk factor for melanoma.

Nonsolar lentigines are sometimes associated with systemic disorders, such as Peutz-Jeghers syndrome (in which profuse lentigines of the lips occur), multiple lentigines syndrome (or LEOPARD syndrome, which stands for multiple Lentigines, Electrocardiogram [ECG] conduction abnormalities, Ocular hypertelorism, Pulmonic stenosis, Abnormal genitals, Retardation of growth, and sensorineural Deafness), or xeroderma pigmentosum.

Lentigo Simplex

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© Springer Science+Business Media

Changes are usually diffuse but sometimes have drug-specific distribution patterns or hues ( see Table: Hyperpigmentation Effects of Some Drugs and Heavy Metals). Mechanisms include

• Increased melanin in the epidermis (tends to be more brown)

• Increased melanin in the epidermis and high dermis (mostly brown with hints of gray or blue)

• Increased melanin in the dermis (tends to be more grayish or blue)

• Dermal deposition of the drug, metabolite, or drug–melanin complexes (usually slate or bluish gray)

Drugs may cause secondary hyperpigmentation. For example, focal hyperpigmentation frequently occurs after drug-induced lichen planus (also known as lichenoid drug eruption).

Treatment of drug-induced hyperpigmentation involves stopping the causative drug; the hyperpigmentation fades very slowly in some if not all cases. Because many drugs that cause skin pigmentation also cause photosensitivity reactions, patients should avoid sun exposure.