Atopic dermatitis (AD) affects 15% to 20% of children and 1% to 3% of adults worldwide.1 It is a condition that every dermatologist is familiar with treating. Currently, most treatments focus more on the medical management behind AD; this is why moisturizers, topical steroids, topical calcineurin inhibitors, dupliumab (Dupixent), phototherapy, and other treatments work. All of these are great and needed treatments by most patients with AD, as they can help relieve the itch, get rid of the rash, and prevent future AD flare-ups.
Most patients are very thankful for these treatments, but many also want “quick fixes” and a relief from “the way their eczema looks.” Further, undertreatment can lead to feelings of depression and suicide.2 These cosmetic concerns can be taken several different ways:
- Patient may be concerned by how rash from eczema (the inflammation) looks;
- Patient is concerned about the postinflammatory hyper- or hypopigmentation remaining from the AD; or
- Patient may have areas of thickened skin from scratching.
Physicians are often good at medically treating the condition, but what can we do to help our patients more instantly and for the long-term from a cosmetic perspective?
The Focus of Cosmetic Treatment
The most important treatment for all cosmetic concerns for AD is prevention. The basis of treatment of every eczema patient should revolve around gentle skin care. This includes taking short (<5 minutes), lukewarm showers, using a gentle unscented soap, and moisturizing.
When a patient has a flare-up of eczema affecting greater than 5% to 10% total body surface area, controlling it with topical steroids can be difficult. Treating AD early with oral prednisone helps relieve the flare-up much quicker. It has been shown that using oral prednisone helps decrease the eosinophil and basophil response in an inflammatory condition.3 By stopping the inflammation early and aggressively, there is less chance of postinflammatory pigmentation changes because the rash resolves sooner.
Alterations in skin pigmentation can be a source of significant emotional distress in individuals, especially those with dark skin complexion in which alterations typically present more dramatically.4 Postinflammatory hyperpigmentation (PIH) is caused by excess melanin deposition following an inflammatory skin disorder, such as AD. Treatment of PIH can be more difficult than treating the preceding condition. Notably, though, the most important aspect of the treatment of pigmentation alterations is time. It can take several months to years for the pigmentation to return to a more normal state, during which the patient can still experience psychosocial complications from the cosmetic appearance.5
Further treatment of pigmentation alterations can be challenging and should focus on decreasing inflammation, exfoliation to encourage cell turnover, and, in the case of PIH, stopping and preventing melanocytic hyperactivity as well as breaking down deposited pigment for removal or release.6
Treatment Options for PIH
Photoprotection. First and foremost, sun protection is critical for any improvement to occur with PIH. Without proper photoprotection, PIH can be exacerbated, adding more distress and psychosocial problems for the patient. Dermatologists should educate their patients on sun safety, including:
- Using a broad-spectrum sunscreen with a minimum sun protection factor of 30 daily;
- Covering up skin when outdoors, especially the PIH-affected areas; and
- Seek shade when outdoors, particularly when the UV radiation levels are high.
Chemical intervention. Along with sun protection measures, topical lightening therapy can be effective for improvement in the appearance of PIH.6 Chemical-based products, such as tretinoin, hydroquinone, azelaic acid, kojic acid, or glycolic acid, have all been used with varying success.4 These different ingredients are often used in combination together and have different strengths. The one big problem surrounding these ingredients is that most cause some form of irritation that is usually compounded in patients with AD. Peels should only be used when an active flare-up has been resolved and when the patient is moisturizing to prevent additional irritation.
Retinoids, such as topical tretinoin, are derived from vitamin A and can be effective either alone or in combination with other agents for the treatment of PIH. These chemical compounds exert several biological effects on PIH, including modulating cell proliferation, differentiation, and cohesiveness; inducting apoptosis; and expressing anti-inflammatory properties.7
Hydroquinone, a phenolic compound, can be an effective tool in treating PIH. This compound prevents dihydroxyphenylalanine from converting to melanin by inhibiting tyrosinase, the rate-limiting enzyme for melanin production. In addition, hydroquinone may inhibit the synthesis of DNA and RNA have selective cytotoxicity toward melanocytes, and enhance melanosome degradation.8
Azelaic acid is a dicarboxylic acid isolate derived from the fungi that causes tinea versicolor. This chemical has two main mechanisms that cause depigmentation: tyrosinase inhibition and inhibition of DNA synthesis and mitochondrial enzymes, creating selective cytotoxic and antiproliferative effects toward abnormal melanocytes. Melanin synthesis is affected by tyrosinase, so inhibiting this enzyme is important in decreasing pigmentation.9,10
Kojic acid is a fungal metabolite of species of Acetobacter, Aspergillus, and Penicillium that inhibits tyrosinase by chelating copper at the enzyme’s active site. This action, again, inhibits the rate-limiting enzyme in melanin synthesis, causing depigmentation. It should be noted that kojic acid is often used in combination with other ingredients as more clinical studies are needed to ascertain its effectiveness.9