Psoriasis in skin of colour

What is psoriasis? Psoriasis is an autoimmune skin condition in which skin cells build up and form scaly rashes on the skin.

Who gets psoriasis? The prevalence in different ethnic groups varies. White individuals have the highest prevalence (3.7%), 2% of those with black skin and 1.6% of those with Hispanic and other skin types. Higher rates of psoriasis are seen in those in eastern compared with western Sub-Saharan Africa. The reported rates of psoriasis in children with black skin appears lower than in those with white skin. In one study, Indian and Malay children were 3-4 times more likely to have psoriasis than Chinese children.

It can start at any age but peaks between 15-25 and 50-60 years of age. 30% will have a family member with psoriasis.

What causes it? Psoriasis is a combination of genetic factors, environmental triggers (infections, severe emotional stress, medications (beta-blockers, anti-malarial medication and rapid withdrawal of systemic corticosteroids and lithium), smoking and excessive alcohol) and production of inflammatory cytokines (proteins that act like messengers).

What does it look like? Psoriasis is classically described as thick, red, scaly spots of skin. But this is not the case for skin of colour. In those with darker skin types, the skin is often less red and is instead brown (pigmentation) or purple in colour. People with darker skin types have, in general, thicker spots, more scaling and greater body surface area than those with Caucasian skin.

Because ‘redness’ is not often seen in skin of colour, the severity of it is often under-estimated by dermatologists. Accurate assessment is especially important when patients are applying for biologic therapy (read below) and need to meet criterion which includes the severity of the psoriasis.

As the spots resolve, they can (especially in those with Indian skin, Chinese skin, Middle Eastern skin, Islander skin, African skin and Hispanic skin) leave areas of darker skin (called post-inflammatory hyperpigmentation) which can last many months to a year, depending on the severity of the original spots.

What other things are associated with psoriasis? Psoriasis c an affect the nails – small dints, thickening of the nail and yellow change (onycholysis) are some of the many signs of nail psoriasis

Psoriatic arthritis is another association causing joint swelling, pain and limited movement. It is less common in African Americans compared with Caucasians. In Singapore, Indian individuals have double the risk of psoriatic arthritis compared with Chinese individuals.

Psoriasis is also associated with cardiovascular problems including obesity, diabetes, high blood pressure, high cholesterol and heart disease.

Depression and lowered quality-of-life has been seen in some patients with psoriasis and those with with darker skin types may experience greater mood disturbance and even lower quality of life. This may be due to multiple factors including post-inflammatory hyperpigmentation, greater body surface area affected, barriers to accessing treatment and social and cultural stigmas associated with skin diseases and the value placed on ‘clear skin’ in some cultural groups.

How is it treated? The treatment of psoriasis has been revolutionised in the last 15 years with the advent of biologic therapies. If a person’s psoriasis is severe enough and other treatments like phototherapy and tablets have not adequately cleared the skin, Medicare may subsidise biologic treatment. There is strict criterion for obtaining these medications through the PBS so please see your dermatologist for more information on this.

It is important to note that most clinical trials have been done in white and Asian populations. Studies in black and Hispanic individuals are lacking.

Treatment generally includes:

1. Optimising lifestyle – exercise, healthy diet and avoiding triggers
2. Optimising skin care – soap free wash and moisturisers
3. Creams – corticosteroids, vitamin D analogues and less common, older generation medications like tar and dithranol
4. Light therapy – narrow band ultra-violet light
5. Oral medicines – methotrexate, cyclosporin, aceitretin
6. Biologic therapies – new, targeted treatments that clear psoriasis

The treatment of psoriasis can be complex. Psoriasis treatments will vary depending on the location, extent and type of psoriasis a person has. While our dermatologists have successfully treated thousands of patients with psoriasis over the years in Melbourne, it is not a condition that can be ‘cured.’ We have however, seen many lives being positively transformed with the newer treatments that are now available.

The information contained in this blog post is intended as a guide only and should not substitute seeking medical attention. Please see your healthcare provider for more information on suitability of products, treatments or procedures.