Hyperpigmentation and Skin of Color
By: Jennifer Linder, MD
Posted: August 23, 2010, from the September 2010 issue of Skin Inc. Magazine.
Much of the world’s population is considered Fitzpatrick type IV–VI. (See Fitzpatrick Scale.) By 2050, according to the U.S. Census Bureau in 2000, 50% of Americans will be of darker-skinned racial backgrounds. One of the most common skin conditions in higher Fitzpatrick clients is hyperpigmentation. Although many of the popular treatments performed on a regular basis on Caucasians may be well-tolerated by clients with darker skin, special considerations need to be taken to ensure positive treatment outcomes for such clients. A deeper understanding of the causes of hyperpigmentation, and of the myriad of ingredients available for its treatment, will help spa professionals develop highly effective therapies for all of their clients, regardless of ethnicity.
Beyond black and white
Within any ethnic background, a variety of Fitzpatrick skin types can be identified. Darker skin can commonly be seen in Hispanics, Latinos, Africans, African-Americans, Caribbeans, Native Americans, Pacific Islanders, East Indians, Pakistanis, Eskimos, Koreans, Chinese, Vietnamese, Filipinos, Japanese, Thai, Cambodians, Malaysians, Indonesians and Aleuts, according to dermatologist Pearl Grimes, MD.1 With this broad global representation in mind, spa professionals should expect to see an increase in clients of one or mixed racial backgrounds with darker skin.
The most apparent difference in the skin of those from different ethnicities is, of course, the color, although there are also differences in skin thickness, vascularity, and predispositions to certain skin conditions and diseases. Hyperpigmentation can occur due to UV exposure, cutaneous trauma or hormonal fluctuations. Studies by dermatologist Susan Taylor in 2005 demonstrate that up to 86% of women of Latino, Asian and African descent are concerned about skin discolorations.2
Melanogenesis and skin color
Melanin is the complex molecule that is responsible for the pigment in the body; specifically eyes, hair and skin. Melanin works to protect by reducing the penetration of UV rays into the skin and, even more importantly, into the nuclei of cells where DNA resides. Those with both dark and light skin have the same number of melanocytes—the cells responsible for melanogenesis or melanin production—although their level of responsiveness differs. Clients whose genetic heredity is that of global regions with extreme UV exposure have melanocytes that will, out of protective necessity, instigate the process of melanin deposition much more quickly than someone with lighter skin. Some clients with mixed genetic heritage may have lighter skin, but still have a greater predisposition for hyperpigmentation than a typical Fitzpatrick skin type I or II.
As a result of inflammation or hormonal fluctuations, the following process is stimulated.
Melanocyte stimulating hormone (MSH) is triggered and released. Within the melanocyte, a chain of events is activated that begins with the enzyme tyrosinase being released from the rough endoplasmic reticulum (RER) and acting on the amino acid tyrosine to convert it to L-DOPA.
Then, tyrosinase binds with copper and acts on L-DOPA, converting it into melanosomes. These melanosomes are packets of pigment that can either be eumelanin (brown/black pigment) or pheomelanin (orange/red pigment). Dark skin tends to have more eumelanin. This more vigorous type of melanin contributes to the increased occurrence of hyperpigmentation in darker skin.
Those with fairer skin, and especially red hair, will predominantly have pheomelanin. The final color of a person’s skin will be slightly different based on the ratio of eumelanin to pheomelanin, as well as the quantity of sustained UV exposure to which their skin is subjected.
The melanosomes produced are then transported along the dendrites, or arms, of the melanocyte and transferred into the keratinocyte. They then congregate in an umbrellalike pattern over the nucleus to protect the DNA within the cell, resulting in visible hyperpigmentation. Protease-activated receptor-2 (PAR-2) is the receptor located in the keratinocytes that regulates whether or not the melanosomes that arrive at the keratinocyte are phagocytized—consumed or taken in. The keratinocytes in skin of color contain more of these PAR-2 receptors, increasing the amount of phagocytized melanosomes by keratinocytes.
Additionally, PAR-2 receptors are increased in number by UV exposure, which may explain the predisposition of darker skin to be more responsive to melanogenesis. All types of hyperpigmentation can affect any person, regardless of race, although this PAR-2 expression and upregulation makes it more prevalent in clients with darker skin.
Gentle treatment optionsMany of the ingredients that are used to treat hyperpigmentation can be topically irritating. Therapeutic ingredients must be selected with care when treating clients with darker skin to avoid causing undue irritation that will worsen the condition rather than improve it.
To avoid stimulating pigment deposition, it is wise to use lower percentages of ingredients in blends to prevent melanogenesis, rather than one ingredient at a high percentage that could potentially be surface-stimulating. Hydroquinone is very effective at the low over-the-counter (OTC) percentage of 2%, especially when used in concert with other effective ingredients, such as lactic, kojic, ascorbic and azelaic acids, just to name a few. Care must be taken when using hydroquinone at 4% or higher on darker skin, as these are more irritating and can trigger post-inflammatory hyperpigmentation.
One of the most important steps in any daily care regimen or professional treatment is that of sun protection. A broad-spectrum moisturizer with an SPF of 30 or greater should be applied to all exposed areas every day and after any professional treatment. Although darker skin has more natural protection against UV exposure, this critical step cannot be omitted. With an understanding of the more reactive state of the melanocytes in clients with darker skin, along with blends of gentle, beneficial melanogenesis-inhibiting ingredients, great success can be achieved in treating Fitzpatrick type IV–VI clients.
REFERENCES1. PE Grimes, Aesthetics and Cosmetic Surgery for Darker Skin Types, Lippincott Williams & Wilkins, Philadelphia, 2008 (pp 15–26)
2. 3. S Badreshia-Bansal and ZD Draelos, Insight into Skin Lightening Cosmeceuticals for Women of Color, J of Drugs in Dermatology 6 1 32–39 (2007)