The role of retinoids in the management of cutaneous conditions in blacks

Abstract

From the Department of Dermatology, Howard University College of Medicine. Reprint requests: Rebat M. Halder, MD, Department of Dermatology, Howard University Hospital, 2041 Georgia Ave., NW, Washington, DC 20060. (J Am Acad Dermatol 1998;39:S98-103.) Copyright © 1998 by the American Academy of Dermatology, Inc. 0190-9622/98/$5.00 + 0 16/0/91854 Black skin is inclusive of 2 large racial groups: natives of the African continent and AfricanAmericans who are a combination of 3 racial groups comprising individuals mainly from West Africa, Native Americans, and Caucasians. The term black skin will be used throughout this review, referring to skin of both Africans and African-Americans. There are known differences between black and white skin, both at the basic science level and at the clinical level.1 The stratum corneum in black skin is more compact. It contains more cell layers, but these are thinner in black skin. In addition, the lipid content of the stratum corneum is higher in black skin. Melanosomes are large and individually dispersed in black skin and numerous even in the stratum corneum. There are more apocrine and eccrine mixed glands in black skin.1 The hair follicle is curved, and the cross-sectional features of black hair are flat and elliptical, which gives a coiled clinical appearance. Black skin has many dilated superficial blood vessels. There also seem to be numerous glycosylated proteins in the matrix of black skin compared with white skin, and there are numerous macrophages in the papillary dermis. Macrophages are large in black skin.1 Black skin has more multinucleated cells compared with white skin. The fibroblasts in black skin are numerous and large, and many are binucleated or multinucleated, which may be responsible for the neat histologic appearance of black dermis in comparison to the chaotic elastosis of white sunexposed dermis.1 This may also be why black skin is firmer and smoother than white skin. The minimal erythema dose of black skin averages between 13 to 15 mJ/cm2 UVB. However, there is wide variation in the skin color in black individuals and in the minimal erythema dose. In terms of photodamage, black skin has marginal changes in the epidermis and dermis, but both black and white skin are susceptible to UV lightinduced immune system suppression. There is greater transepidermal water loss in black skin compared with white skin.1 Acne vulgaris is the most common dermatosis seen in black individuals, accounting for 27% of the dermatoses (Table I).2 This is not different from white individuals. However, pigmentary disThe role of retinoids in the management of cutaneous conditions in blacks