A Closer Look At Dermatologic Conditions In Skin Of Color
Given the changing population demographics in the United States, it is more important than ever to be able to recognize and treat dermatologic conditions that are more prevalent among patients with skin of color. Accordingly, this author discusses the diagnosis and treatment of skin conditions including vitiligo, melanonychia and keloids.
As a physician whose primary practice consists of patients with skin of color, I am particularly concerned with the diagnosis and management of skin conditions prevalent in this population. What does the term “skin of color” encompass? It is the accepted dermatologic term to describe our patients with all shades of pigmented skin: African-American, Hispanic, Asian (East, Southeast and South), and non-Caucasian ethnic groups such as First Nations/American Indian/Alaskan Native/Native Hawaiian.
The United States Census has projected that half of the population will be comprised of people with skin of color by 2050.1 In most cities in the United States, 2050 has already arrived. For example, I work in Philadelphia, where people with skin of color comprise over 57 percent of the population.1 Accordingly, as the demographics of the population change, it is important that the podiatric physician is familiar with the skin conditions that are of particular concern in this group.
First, it is important to recognize the structural and biological differences between African-American and Caucasian skin. Skin color is determined by the distribution of melanin and there is no difference in the number of melanocytes among groups. The melanocytes, which reside in the basal layer of the epidermis, contain melanosomes filled with tyrosinase that is involved in melanin synthesis. Interestingly, the amount of tyrosinase is generally equal in African-American and Caucasian skin.
However, the distribution of melanosomes within melanocytes and keratinocytes is different between skin pigments. Besides the distribution of melanosomes contributing to skin color, tyrosinase levels are 10 times higher in African-American skin and produce 10 times more melanin than melanocytes in Caucasian skin.2 Melanocytes in those with skin of color seem to respond to injury and inflammation, which helps to explain the pigmentation changes.3
There are other variations in the epidermis and dermis between African-American and Caucasian skin. Epidermal thickness is equivalent but there are more epidermal lipids in African-American skin.4 Transepidermal water loss is lower in African-American skin, showing statistical significance on the legs in a study by Warrier and colleagues.4 Regarding the dermis, fibroblasts are more numerous, larger and physiologically active in African-American skin, which could help to explain the prevalence of keloids and hypertrophic scars in this patient population.5
Whether one is examining a patient with skin of color for the first time or treating a new area of pigmentation following a podiatric surgical procedure, pigmentation disorders, inflammatory conditions and abnormal scar healing are the most common issues we see as podiatric practitioners.
When examining patients with skin of color, it is helpful to note that the angry red color in cellulitis or the erythema in psoriasis/inflammatory skin conditions may appear as a more subtle red or even have a purple hue to it. As with any patient, a thorough history and physical is warranted along with a comparison of the contralateral limb and skin on the rest of the extremity. Once a patient has recovered from an infection or an inflammatory condition, the practitioner has to be concerned with both hyper- and hypopigmentation of the affected area.