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Pittsburgh - Proper patient evaluation, controlling a patient's melanocytes before employing in-office procedures and creating a combination skincare regimen are all primary keys to success in treating patients with hyperpigmentation, according to Suzan Obagi, M.D., assistant professor of dermatology and director of the Cosmetic Surgery and Skin Health Center, University of Pittsburgh School of Medicine, Pittsburgh.
"Patients who come to our center frustrated with previous treatments tend to have been treated with only one modality," Dr. Obagi says. "A patient may have been told, for example, to go through a series of chemical peels or microdermabrasion (treatments) for hyperpigmentation. This is a big mistake." When these procedures are used as monotherapy, Dr. Obagi explains, the patient at best sees an immediate improvement that only lasts the length of time it takes for pigmentation to return. Worse, hyperpigmentation can actually be aggravated with some forms of aggressive treatment.
Factors affect therapeutic approach The therapeutic approach to hyperpigmentation is complicated by a number of factors. Hyperpigmentation disorders include a multitude of forms, which are intimately related to the ethnic background of the patient. The most common are lentigines (a solar-induced condition more commonly occurring in fair-skinned individuals), melasma (a hormonally driven condition prevalent in medium to darker complexions) and post-inflammatory hyperpigmentation (associated with acne or areas of trauma in medium to darker complexions). Furthermore, the underlying mechanism causing the increased melanin is variable, as is the location in which it occurs (dermis, epidermis, or both).
Skin lightening agents In the skin, melanocytes continuously produce melanosomes, which are distributed to the adjacent keratinocytes. Melanocyte pigment production relies on the conversion of tyrosine to melanin via the enzyme tyrosinase. Tyrosinase inhibitors, which prevent the formation of melanin, are commonly employed as depigmenting agents. Among these, hydroquinone is considered the gold standard for skin lightening, but has been banned in some countries out of concern for toxicity or possible carcinogenesis when used at high concentrations. This has led to a search for and discovery of other depigmenting agents with milder action, including licorice extract, kojic acid and azelaic acid. Dr. Obagi stresses that when used correctly, under physician supervision, hydroquinone continues to be safe and far superior to other lightening agents available. Kojic acid has a slightly increased chance of causing contact dermatitis, while azelaic acid is only a weak lightening agent at best.
Adding keratolytic agent As melanocytes transfer from the melanosomes to the keratinocytes, the areas of hyperpigmentation become clinically apparent. Therefore, adding a keratolytic agent to the skincare regimen can help accelerate the shedding of the pigment containing keratinocytes. This exfoliation process can be expedited by using alpha hydroxy acids such as lactic acid or glycolic acid. A combination treatment employing both tyrosinase inhibitors and exfoliating agents produces a more dramatic improvement than either agent used alone. The alpha hydroxy acids break up keratinocyte adhesions, thus allowing all other topically applied agents to penetrate deeper.
Tretinoin, sunscreen, laser tx Dr. Obagi believes that clinicians tend to underestimate a third type of topical agent, the vitamin A derivatives (i.e., tretinoin). Tretinoin not only increases the turnover of cells, but also has been shown to alter the distribution and activity of melanocytes after long-term use. Furthermore, it effectively reduces and reverses sun damage.
Because ultraviolet radiation is an extremely influential environmental trigger of hyperpigmentation, regular use of sunscreens that offer broad-spectrum protection is perhaps the most important intervention for any patient. Without including sun protection in the topical regimen, repigmentation of treated areas is guaranteed to occur.
For patients seeking more aggressive treatment, Dr. Obagi advises that among adjuvant therapies, lasers provide a much larger safety margin than light-based technologies. Q-switched lasers, originally used in tattoo removal, are now gaining ground in hyperpigmentation treatment and are available in wavelengths that can treat the epidermis (532 nm), the dermis (1064 nm) or both (755 nm).