How is Psoriasis Different in Those with Darker Skin

In recent years, psoriasis among those with darker skin has become a topic of interest, partly due to the large spectrum of skin tones that psoriasis affects. Psoriasis affects roughly 7.4 million Americans ranging from all ages and backgrounds.^[1] With the ever-growing diversity of ethnic groups, there is a greater need to understand the different nuances of psoriasis in those with darker skin.

Post-Inflammatory Hyperpigmentation and Hypopigmentation

Individuals with darker skin tones have a higher risk of developing changes in skin color as a result of skin inflammation.^[2]  As psoriasis lesions heal, the skin in the area can either become darker, known as post-inflammatory hyperpigmentation, or lighter, known as post-inflammatory hypopigmentation. The severity of skin color changes is also greater in darker skin tones.^[2] Multiple studies have shown that the change in skin color is the main reason darker toned individuals seek help from a dermatologist.^[2]

What about psoriasis causes this change in skin pigmentation? It turns out that the same inflammatory factors that drive psoriasis (TNF and IL-17) also affect the production of pigment in the skin.^[3] Both of these inflammatory factors alter skin pigment because they can induce the skin’s melanocytes (the skin’s pigment-producing cells) to produce melanin pigment. During inflammation, there are many signals that can trigger the melanocytes to produce pigment.^[2] This leads to hyperpigmentation, especially in those with darker skin. In some cases, the inflammation can keep the melanocytes from functioning properly and lead to areas of lighter pigmentation (hypopigmentation).

One of the biggest concerns with post-inflammatory hyperpigmentation is how long it takes to resolve. Post-inflammatory hyperpigmentation and hypopigmentation may persist for several months to several years, especially if the inflammation in the psoriasis lesion is not relieved quickly. These darkened skin areas can be just as distressing or even more distressing than the actively inflamed psoriasis lesions.  

Increased Area of Involvement

One study showed that African Americans reported having a larger area of their skin afflicted with psoriasis. They approximately have 3-10% of the body surface area involved compared to an average of 1-2% body surface area involvement in the Caucasian group.^[4]

Unique Features with Scalp Psoriasis

Hair texture, length, care, and styling are all factors that affect treatment modalities for those with darker skin. In the African American population, practices such as hair relaxers, braids, weaves, and locks may all affect treatment outcomes and create difficulties,^[4] mostly due to the fact that topical scalp treatments are not catered to these hair-care products and regimens. Even if the treatment is scientifically effective, its inability to compliment certain hair-care practices may be reason enough for a person to discontinue its use. 

Hair-washing frequency is another factor to note, especially when a topical treatment recommends a daily hair wash. Treatment practicality affects how well the regimen can be followed and is important for successful results. For a physician or care provider, it means looking for products that do not damage the hair, alter styling, and do not require every-day shampooing. For a patient, it’s important for them to tell their doctor about their hair care practices so that they can decide on treatment approaches that will work with their ongoing hair care practices.

Phototherapy Treatment

One of the most popular, successful, and safest treatment options for psoriasis is phototherapy. In darker skin tones, phototherapy can cause skin darkening if burns occur during the treatment.^[4] If the patient already has pre-existing scars or marks, it may darken them as well. Also, phototherapy can have an overall “tanning effect” on darker individuals, which along with post-inflammatory hyperpigmentation can be disfavored by some patients. For doctors, it is important that they know about these concerns. For patients, voicing these concerns can help their doctor better choose the right treatment for your psoriasis.

Social Factors

Quality of life is an important reason why patients with psoriasis seek out a dermatologist. Patients who suffer from psoriasis deal with a great load of stress due to the constant itching, a larger area of affected skin, and obvious skin presentation that can be embarrassing. Patients with darker skin also deal with the aftermath effects of post-inflammatory hyperpigmentation, hypopigmentation, scarring, and unappealing topical agents that may not suit their skin and hair practices.