Do you have dark spots on your skin that appeared after a flare-up of acne? If yes, you may have a skin condition called postinflammatory hyperpigmentation (PIH). PIH can be unsettling, especially when the face is affected. Understanding the underlying cause and possible treatments for PIH is the first step in alleviating anxiety and deciding the best therapy for you.

Your inherent, normal skin color is the result of a genetically determined mixture of pigments, including the dark-colored pigment called melanin. Skin color can be altered by either internal factors (i.e., disease states) or external factors (i.e., the sun or chemicals). Some patients, for example, may produce excessive amounts of melanin after their skin is inflamed with acne. The resulting postinflammatory hyperpigmentation is characterized by the appearance of dark spots on the skin. PIH is usually more prominent in people with inherently dark skin, although light-skinned people may experience similar changes in skin color. Understanding the extent of the pigmentary disturbances is the key to deciding the best course of treatment for skin spots.

In determining a course of treatment for localized skin color changes, a critical deciding factor is whether or not the spots of dark pigment only appear in the superficial layer of skin (the epidermis) or if they extend into the deeper layer of skin (the dermis). Your physician can detect the depth of color changes in your skin by using a special light called a Wood’s lamp. If the dark spots only appear in the epidermis, treatment is easier and the spots usually disappear in less than a year. If the dark pigment extends into the dermis, treatment is more complicated and spots may persist for months or even years. People with naturally dark skin are at higher risk for PIH affecting the dermis.

POSTINFLAMMATORY HYPERPIGMENTATION TREATMENT OPTIONS

Before starting treatment, patients should understand that there is no single “magic bullet” to remedy postinflammatory hyperpigmentation. Luckily, multiple agents are available for therapy which can be used either alone or in combination. During therapy, patients are advised to protect themselves from sunlight because exposure to ultraviolet radiation may exacerbate and prolong PIH.

A number of pigment-altering agents are currently available for postinflammatory hyperpigmentation therapy. They may be used alone or in combination to treat pigment disorders. One such medication is Hydroquinone (HQ). HQ blocks the activity of tyrosinase–the key melanin-producing enzyme. Low concentrations (up to 2%) of HQ are available over-the-counter and considered safe, but they are not very effective in treating PIH. Higher concentrations of HQ are available, though they may cause irritation, sensitization, and additional PIH in some people. However, positive results are possible following HQ treatment, especially when combined with other pigment-altering agents. However, several weeks or months may pass before change is evident.

Another medication used for treating postinflammatory hyperpigmentation is Azelaic Acid (AZA or Azelex). Like HQ, this agent also inhibits the activity of tyrosinase. When used alone (monotherapy), AZA is effective in treating pigmentary and acne disorders over a period of several months. Reported adverse events include burning, itching, flushing, and stinging. Efficacy of AZA in treating melasma (brown spots/patches that usually occur on the face) is similar to that of HQ 4%. When AZA is combined with retinoic acid (discussed below), a noticeable and more pronounced decrease in pigmentation occurs earlier as compared to that seen after AZA monotherapy. Unlike some other agents, AZA does not cause sensitivity to sunlight or residual increases or decreases in skin pigment. Also, the incidence of allergic sensitization is less than that experienced after treatment with other depigmentation medications. These factors make AZA a primary medication for treating acne patients with postinflammatory hyperpigmentation.

Topical vitamin A (tretinoin) is used to treat PIH. Although the exact mechanism of action is not understood, tretinoin appears to inhibit the production of melanin. Studies show that tretinoin is effective in the management of postinflammatory hyperpigmentation and melasma over a period of several months. Tretinoin also is effective in treating acne. Until ten years ago, the use of tretinoin alone for treating pigmentary disorders was limited because long-term application is necessary and adverse effects such as skin irritation and sensitivity to sunlight are possible. However, several products, such as Differin, Renova, Retin-A micro, and Avita, are currently on the market and have a lower incidence of irritancy than the original tretinoin formulations.

Corticosteroids also block activity of tyrosinase. Low potency corticosteroids are used for treating postinflammatory hyperpigmentation, although they rarely are used alone because of multiple adverse effects that include thinning of the skin, the appearance of streaks or decreased pigment spots on the skin, and dilation of superficial blood vessels. Corticosteroids usually are used in combination with other pigment-altering medications, especially HQ and tretinoin. Corticosteroids provide relief from the irritation caused by HQ and tretinoin, and the components of this combined therapy can be altered to accommodate varying skin types and the depth of pigment in the skin. Some dermatologists also add AZA to the corticosteroids, HQ, and tretinoin combined therapy, while others replace tretinoin with alpha hydroxy acid (discussed below) to reduce adverse effects.

Alpha hydroxy acid (AHA) is useful for superficial pigmentary changes, as well as certain forms of acne. Prolonged application is usually necessary to achieve an effect. The percentage of AHA can be adjusted, based on the level of skin irritation the patient experiences. To minimize irritation, AHA is often incorporated in emollient bases to minimize irritation. To augment postinflammatory hyperpigmentation treatment, AHA is often combined with AZA or HQ. Potential adverse effects of AHA are similar to those seen with AZA treatment (discussed above).

Trichloroacetic Acid (TCA) is effective in treating spotty postinflammatory hyperpigmentation. However, TCA is highly reactive and can cause damage to the epidermis, so dilute solutions are applied initially to test and determine the optimal treatment concentration for each patient. The concentration that produces a safe amount of skin peel is used, and through continuous treatment, the pigmented spot eventually disappears. Unfortunately, TCA not an effective treatment for dark-skinned patients with PIH because additional PIH and scarring may occur. In patients with light skin, TCA treatment can be good, but results are inconsistent.

Another treatment for postinflammatory hyperpigmentation is liquid nitrogen (LN). LN is used to gently freeze and reduce the color of superficial dark spots after repeated applications. Cells that produce melanin (melanocytes) are very susceptible to LN. Liquid nitrogen must be used with caution in patients with dark skin because they may develop permanent loss of pigment at the treatment site.

Lasers are used to effectively treat pigmented skin spots without causing scars or loss of normal skin color. Lasers target pigment-producing cells and their depth of skin penetration can be adjusted, depending on the type of laser used. There are different kinds of lasers, and each type of laser has its own risks and benefits; some are effective in treating superficial pigment spots, while others are better for treating deeper pigmentation.

If you choose to forgo the treatments discussed above, cosmetics always can be used to camouflage unsightly spots. An initial evaluation by a make-up therapist is recommended to help patients identify the underlying color of the spot, their skin tone and texture, and then successfully match a cover cream to their skin. Cover creams are usually waterproof, opaque, and available in a multitude of colors. Several acne medications also provide some measure of tinted cover-up, such as Liquimat, Loroxide, Resamid, and Sulfacet-R lotions.

Although there are no quick and easy treatments to resolve postinflammatory hyperpigmentation after acne, patients should be reassured that there is help for the condition. In most cases, the areas of PIH will eventually disappear–even when left untreated. Patients who have PIH with acne must initially be assessed for the depth of skin pigment change. In cases where dark spots extend into the dermis, treatment may be more difficult, but not impossible. Therapies using different combinations of the medications described above appear to be more effective and expeditious in treating postinflammatory hyperpigmentation than those using a single agent alone.

Finally, in conjunction with treatment, patients must remember to avoid excessive washing (more than twice a day) with soap because doing so may irritate or excessively dry the skin and exacerbate the acne and postinflammatory hyperpigmentation. Instead, Cetaphil cleanser or other pH-balanced liquid cleansers are recommended for washing. Finally, exposure to sunlight should be avoided. Because ultraviolet radiation will make most skin pigment disorders worse, the use of protective clothing and an oil-free moisturizer with SPF 15 or greater are important factors in treating postinflammatory hyperpigmentation.

Drs. Solomon, Falcon and Buscemi are clinical assistant professors of dermatology at the State University of New York Health Science Center, Brooklyn. Drs. Solomon and Falcon are members of the Island Skin Cancer Research Group in Long Beach, NY.