*Revised with permission from: R Pugashetti and H Maibach, Pigmentation in Ethnic Groups, ch 52 in Aging Skin, MA Farage, KW Miller and HI Maibach, eds, New York: Springer (2010) pp 503–508.
The US Census Bureau estimates that by 2050, approximately half of the US resident population will be individuals of color. While human skin color is a trait that distinguishes people of different races, it remains unclear how variations in human skin pigmentation may contribute to differences in skin structure, function and pathophysiology. As formulators create products for varying ethnic backgrounds and with diverse skin types, an understanding of differences in pigmentation and skin structure and function becomes more important. This column reviews recent studies on the structural, genetic and ultraviolet (UV)-responsive differences in skin pigmentation to allow the formulator to create successful products for varying ethnicities and to accurately measure pigmentation.
Structural Differences in Pigmentation
Montagna and Carlisle examined the morphology of black and white facial skin among adult women ages 22–50, including factors such as atrophic spots, elastosis, fiber fragments, sweat glands and the condition of the stratum lucidum. Their observations were as follows:
Atrophic spots: Atrophic spots, or areas of the skin that appear thinner, were demonstrated frequently in white skin, while only 1 in 19 black women in the study demonstrated atrophic spots in the epidermis.
Elastosis: One of the key indices of dermal photodamage is the presence of elastotic material. Elastosis can be measured by looking at skin biopsy samples to identify the amount of elastotic fibers present. Black skin demonstrated minimal elastosis while white skin showed variable amounts of moderate to extensive elastosis. The authors speculated that greater numbers of melanosomes and distribution in black skin perhaps protect the epidermis from photodamage.
Fiber fragments: The dermis of black skin demonstrated more fiber fragments made of collagen fibrils and glycoproteins than white skin, as well as numerous and larger fibroblasts.
Sweat glands: Black skin showed more mixed apocrine-eccrine sweat glands and more blood and lymphatic vessels than white skin.