Chapter 14: Skin of Color

INTRODUCTION

Skin of color describes individuals with increased epidermal pigment and darker skin. This subset of patients has unique cosmetic concerns and often requires special consideration for cosmetic procedures. Skin of color is typically seen in those of African, Hispanic, Asian, and Southeast Asian descent.

BIOLOGY OF SKIN COLOR

There is little variation in the number of epidermal melanocytes between light- and dark-skinned individuals. There are approximately 2000 epidermal melanocytes/mm² on the head and forearm and 1000 epidermal melanocytes/mm² on the rest of the body. These differences are present at birth.¹ Thus, all persons have the same total number of melanocytes.

Although increased epidermal pigmentation results in a darker skin phenotype, there are actually more distinct ultrastructural characteristics that correlate with skin color. Specifically, the distribution of melanosomes in the keratinocytes correlates with skin color. In white skin, melanosomes are small and aggregated in complexes. In black skin, there are larger melanosomes, which are singly distributed within keratinocytes.²

Interestingly, the distribution of melanosomes in darker skin varies with the location on the body. In lighter skin, keratinocytes of both the thigh and volar skin exhibit complexed melanosomes. However, keratinocytes from the thighs of dark-skinned patients display singly dispersed melanosomes, while keratinocytes from the lighter volar skin of these patients have complexed melanosomes.³ Thus, the melanosomes in the minimally pigmented volar skin of dark-skinned individuals closely resemble the melanosomes of lighter-skinned individuals. This finding further supports the theory that skin color correlates with the distribution of melanosomes. From such studies, one can conclude that melanosome distribution correlates with the color of skin; however, skin color is also determined by other factors.

One study examined the contribution of melanin, oxyhemoglobin, and deoxyhemoglobin on pigmentation observed clinically after ultraviolet B (UVB) exposure. The investigators found that the clinical evaluation of skin complexion was affected both by epidermal melanin concentration and deoxyhemoglobin residing in the superficial venous plexus. Additionally, altering the concentration of deoxyhemoglobin in the skin with pressure or with topical therapies also significantly altered what is visually perceived as skin pigmentation.^4,5

CATEGORIZING SKIN OF COLOR

Fitzpatrick Skin Typing System

Skin of color is most frequently defined as Fitzpatrick skin phototypes (SPT) IV through VI. These skin types, by definition, tan easily or profusely and burn minimally, rarely, or never. The Fitzpatrick SPT system was originally developed to assess a patient’s response to UV exposure for the purpose of treating skin conditions with light.⁶ Using this system, patients are assigned a skin type based on the reported ability to tan or burn. The SPT defines a minimum erythema dose (MED) for each skin type, which is then used to guide dosing of UV therapy for various skin diseases. This skin typing system has since evolved into a way ...