Special Considerations in Skin of Color

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What is “skin of color”?

There are many ways to subcategorize humans. Widely recognized racial groups include Africans, African-Americans, Asians, Middle Easterners, Northern Europeans, Native Americans, Pacific Islanders, and Hispanics, to name a few. Even within a racial group, gradations exist with regard to skin pigmentation. Simply put, people with “skin of color” have darker skin tones than those of typical white skin. The term may be used also to reference other shared cutaneous characteristics, such as hair color or quality, or a common reaction pattern to skin insults, all of which may be clinically relevant. By 2044, more than 50% of the U.S. population will be composed of people with skin of color. Accordingly, a solid understanding of the myriad differences in diagnosing and treating persons with skin of color is essential to the competent practice of dermatology.

Taylor SC, Cook-Bolden F. Defining skin of color. Cutis. 2002;69:435–437.

U.S. Census Bureau. 2008 National Population Projections: Tables and Charts . https://www.census.gov/data/tables/2008/demo/popproj/2008-summary-tables.html . Accessed September 7, 2020.

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How might these ethnic differences impact upon the practice of dermatology?

While diversity in the population is increasing, there is concern that the ethnic composition of dermatologists, who spend 12 years in higher education and 20–40 years in clinical practice, may not diversify at the same rate. For example, a 2017 survey found the current ethnic make-up of dermatologists to be 68% white, 15% Asian, 6% black, and 3% Latino; this does not correspond to the ethnic make-up of the general population. Therefore, it is important that practicing dermatologists undergo appropriate education on the skin care practices and concerns of persons with skin of color. In fact, a recent study found that for black patients, even when there was no racial concordance between the dermatologist and the patient, there was increased patient satisfaction when the dermatologist had familiarity with and specialized knowledge of the care of black skin and hair.

Gorbatenko-Roth K, Prose N, Kundu RV, et al. Assessment of black patients’ perception of their dermatology care. JAMA Dermatol . 2019;155:1129–1134.

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What accounts for differences in color between ethnic and racial groups?

Although the number of melanocytes varies within anatomic regions of the body, interestingly, among different races and ethnicities, the actual number of melanocytes in the skin does not vary with skin color. Instead, among variations, it is the amount and distribution of melanin produced that changes. In mammals, two types of melanin are produced by melanocytes, eumelanin and pheomelanin. Eumelanin is a tyrosine-derived dark brown or black pigment. Pheomelanin, derived from a biochemical shunt in the normal melanin production pathway, has a yellow to red-brown hue. Pheomelanin is the predominant pigment produced by those with freckles and red hair. It is also increased in Asian skin, and in women when compared to men. Melanin is packaged in melanosomes, which are membrane-bound vesicles containing a unique scaffolding of matrix proteins. Melanosomes within keratinocytes of white skin are distributed as membrane-bound clusters. In black skin, melanosomes tend to be larger and more diffusely located in the cell. Therefore, the quantity and composition of melanin, as well as melanosome size and distribution, vary considerably within the epidermis, both with ethnicity and with chronic sun exposure, yielding various degrees and hues of pigmentation.

Thong HY, Jee SH, Sun CC, et al. The patterns of melanosome distribution in keratinocytes of human skin as one determining factor of skin colour. Br J Dermatol. 2003;149:498–505.

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Do any physiologic differences exist between black skin and that of other racial/ethnic groups?

Yes. In truth, the color of “black” skin ranges from light brown to very dark brown/black, and it is difficult to generalize given this tremendous variability. Nevertheless, studies have demonstrated that the stratum corneum of most black skin maintains more layers and is more compact and cohesive than white skin. This finding may explain why black skin tends to manifest a decreased susceptibility to cutaneous irritants. One study demonstrated that black skin had a spontaneous desquamation rate 2.5 times that of white skin, and this may explain why some blacks experience a particular type of xerosis commonly referred to as ashy skin . Ashy skin consists of fine white flakes yielding a dry appearance. Other differences in black skin include an increased transepidermal water loss, lower pH, and larger mast cell granules when compared with white skin. Black skin also produces less vitamin D ₃ in response to equivalent sunlight, and this has been postulated to possibly represent the driving evolutionary force in development of paler skin as early humans migrated away from the equator. Conflicting data exist regarding differences in resistance, capacitance, conductance, impedance, and skin microflora.

Jablonski NG, Chaplin G. The evolution of human skin coloration. J Hum Evol. 2000;39:57–106.

Wesley NO, Maibach HI. Racial (ethnic) differences in skin properties: the objective data. Am J Clin Dermatol. 2003;4:843–860.

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What are the “ashy dermatoses”?

In addition to the term “ashy,” used to refer to a characteristic type of xerosis among blacks, there are also “ashy dermatoses,” a term that refers most often to a family of conditions observed in Latinos. Other terms, such as “erythema dyschromicum perstans,” “lichen planus pigmentosus,” and “idiopathic eruptive macular pigmentation,” may refer to these same conditions, which maintain overlapping clinical features. Some dermatologists consider these “ashy dermatoses” to be variants of lichen planus (see Chapter 12 ). Clinically, these ashy dermatoses present as macules or even large patches, with brown to grayish hues of pigmentation with scant erythema. Under a microscope, there is often a subtle lichenoid interface reaction, with underlying pigmentary incontinence in the shallow dermis. While there is not full consensus among dermatologists, it may be the degree of inflammation and the extent of involvement that distinguishes “ashy dermatoses” from frank lichen planus. Unless one practices in Latin America, or among a largely Latino community, it is probably adequate simply to be aware of the disparate viewpoints.

Zaynoun S, Rubeiz N, Kibbi AG. Ashy dermatoses—a critical review of the literature and a proposed simplified clinical classification. Int J Dermatol. 2008;47:542–544.

Vega-Memije ME, Domínguez-Soto L. Ashy dermatosis. Int J Dermatol. 2010;49:228–229.

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Are the brown streaks on the nails of people with skin of color always a cause for concern?

No. Pigmented streaks of the nail may be a normal variant in people with skin of color. The condition is called melanonychia striata , and it is characterized by longitudinal bands of pigmentation that may vary from light brown to dark black. Multiple bands may be seen within the same nail or, alternatively, several nails may be involved. The cause is unknown, but the rarity of bands in children may indicate that they are a sequela of accumulated trauma. Some studies have revealed that such bands are present in 75% of blacks older than 20 years. Another recent study found that simple racial variation was the most common cause of nail pigmentation in Hispanics as well, although malignancy was a cause in about 6% of cases. In general, solitary bands are of greater concern than are multiple lesions. Close examination of the nail fold may be helpful, assessing for diffusion of pigment into the surrounding skin; however, the absence of this sign does not rule out a more serious condition, such as nail unit melanoma. Other causes of nail pigmentation include drugs such as actinomycin, antimalarials, bleomycin, cyclophosphamide, doxorubicin, 5-fluorouracil, melphalan, methotrexate, minocycline, nitrogen mustard, and zidovudine, to name a few. Laugier-Hunziker syndrome, Addison's disease, hemochromatosis, Peutz-Jeghers syndrome, and vitamin B ₁₂ deficiency may also cause nail pigmentation.

Dominguez-Cherit J, Roldan-Marin R, Pichardo-Velazquez P, et al. Melanonychia, melanocytic hyperplasia, and nail melanoma in a Hispanic population. J Am Acad Dermatol. 2008;59:785–791.

Pappert AS, Scher RK, Cohen JL. Longitudinal pigmented nail bands. Dermatol Clin. 1991;9:703–716.

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Is pigmentation of the oral mucosa in people with skin of color invariably concerning?

No. Pigmentation of the oral mucosa is often subdivided into conditions related to melanin (including racial differences in pigmentation) and non–melanin-associated conditions, such as metabolic conditions or pigmentation related to drugs. Therefore, oral pigmentation in people with skin of color is neither uncommon nor necessarily indicative of a serious condition. Idiopathic, racially related pigmentation of the oral mucosa often involves the gingiva, palate, buccal mucosa, or tongue ( Fig. 63.1 ). The color may vary, but it often has a blue or gray appearance. Symmetry is frequently observed. As always, obtaining an appropriate medical history is important, particularly with respect to the length of time present and any associated symptoms.

Meleti M, Vescovi P, Mooi WJ, et al. Pigmented lesions of the oral mucosa and perioral tissues: a flow-chart for the diagnosis and some recommendations for the management. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;105:606–616.

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Are there other areas of the body where hyperpigmentation represents a normal racial variant?

Hyperpigmented macules of the palms and soles occur in people with skin of color, particularly in those with darker skin types. Such lesions may vary in color from light tan to dark brown. The number of lesions may range from one or two lesions to dozens or more. This potential for natural racial variation must be kept in mind, particularly when one considers other diseases associated with palmoplantar lesions, such as erythema multiforme and secondary syphilis. As acral lentiginous melanoma is the most common form of melanoma occurring in blacks, Asians, and Hispanics, this potentially life-threatening diagnosis must always be considered, and excluded by biopsy where indicated. Other areas with possible increased pigmentation among persons with skin of color include the sclera, the labia and vaginal mucosa, and the glans penis.

Coleman WP III, Gately LE III, Krementz AB, et al. Nevi, lentigines, and melanomas in blacks. Arch Dermatol. 1980;116:548–555.

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