Skin of colour characteristically reacts to common dermatoses in different ways to lighter skin tones. An appreciation of these subtle, yet crucial, differences is essential for clinicians to make the correct diagnosis.

In Western Europe, dermatology evolved as a distinctive medical specialty from the late 18th Century onwards. The overwhelmingly predominant skin colours at the time – and until well into the 20th Century – were lightly-pigmented European tones. For this reason, textbooks classifying skin disease described common skin conditions in terms of how they present in white skin, with little or no reference to presentation in skin of colour.

Population demographics have changed significantly since then – with an influx of people with more pigmented skin arriving in the UK after World War II – but medical textbooks, undergraduate and postgraduate medical education and online resources have largely not deviated from white skin being the reference skin tone.

This makes it difficult for clinicians to competently and confidently diagnose common skin conditions in people of colour.

Erythema

In white skin, the hallmark of inflammatory skin disease is erythema, which presents as shades of pink and red of varying intensity. However, erythema is often imperceptible in skin of colour because the widespread dispersion of melanin throughout the stratum corneum masks the redness of inflammation. Instead, inflammation may present as shades of violet and purple, or as an increase in pigmentation leading to a darkening of the skin.

Erythema (as a result of toxic epidermal
necrolysis) in white skin and skin of colour

^{(Image credit: DR M.A. Ansary/Science Photo Library)}

Eczema

Eczema occurs in all ethnic groups, but higher incidences have been reported in black and Asian populations, in comparison with their white counterparts. Additionally, children of African heritage are twice as likely to experience severe disease than children of European heritage.

Eczema presents as itchy areas of skin, which can form papules and blisters in the acute phase and scaling and lichenification in the chronic phase (see image). Dry skin, fissures, and staphylococcal and herpetic infection are common in eczematous skin. In skin of colour, hyperpigmentation is present in the acute and chronic phases. Once the inflammation has resolved, post-inflammatory hyper- and hypopigmentation may persist for several months.

Eczema can distribute on the skin in different patterns. Classically, the flexural presentation is most often described. However, in skin of colour, extensor, follicular and discoid presentations are common. These distribution patterns are extremely rare in children of European heritage. Lichenification is also more common in skin of colour than it is in white skin.

Eczema on the foot: lichenification is
common in skin of colour

^{(Image credit: Science Photo Library)}

Acne

Acne is prevalent in all skin types and is most commonly seen in teenagers and pre-menopausal women. The hallmark of acne is the comedone, which evolves into papules and then pustules and cysts. Seborrhoea is a common feature.

People of colour present with hyperpigmentation of papules and pustules (see image). Cystic acne is less common in skin of colour than in white skin.

Pomade acne – presenting as widespread comedones, particularly on the forehead – is common in those with afro-textured hair, where hair products that can trigger acne are used to style or treat the hair. Advice on avoiding these, and any occlusive skin care products, is necessary.

Post-inflammatory hyperpigmentation and keloid scarring are long-term complications that are more likely to occur in skin of colour and can be associated with severe morbidity.

Acne treatment is the same for all skin types. However, in skin of colour, the management of peri- and post-inflammatory hyperpigmentation should be part of standard acne treatment. This should involve the use of broad-spectrum sunscreens, antioxidants with dark mark lightening qualities such as azelaic acid 20%, and advice against using any treatments that may traumatise skin and potentially lead to exacerbation of the pigmentation.

Acne: management of hyperpigmentation
is important in skin of colour

^{(Image credit: Dr Sharon Belmo)}

Psoriasis

Prevalence rates of psoriasis vary in different ethnic groups. The highest rates are found in Scandinavia and the lowest rates are among indigenous people of the Americas.

Textbooks usually describe psoriatic plaques as being salmon pink with an overlying silver scale. In skin of colour, erythema is very difficult to discern and, instead, psoriasis may present as violaceous, hypochromic, or darker-than-usual skin colour plaques with a grey overlying scale.

In skin of colour, as in lighter skin, the plaques are sharply demarcated and have a predilection for extensor surfaces, the umbilicus, the hairline and intertriginous areas. Nails and joints can also be affected.

Post-inflammatory hypo- and hyperpigmentation are prevalent and bothersome in skin of colour, but treatment of psoriasis is the same regardless of skin tone and follows a stepwise approach.

Psoriasis on the lower back: erythema is
difficult to discern in skin of colour

^{(Image credit: Science Photo Library)}

Lichen planus

Lichen planus is an autoimmune condition where auto-reactive T-cells attack the basal keratinocytes. The cause is often idiopathic but it may be associated with hepatitis C and certain medications, including antihypertensive drugs, antimalarials and NSAIDs.

Lichen planus is typically described as the 6Ps: pruritic, polygonal, planar, purple papules and plaques, found particularly on the flexor surfaces of the wrists, the dorsal surfaces of the hands and the anterior surface of the lower legs. In skin of colour, the ‘purple’ in this list is often substituted for an increased pigment (darker-than-usual skin colour), a violaceous colour (see image) or hypopigmentation.

Post-inflammatory hyperpigmentation is common and often more troublesome in darker skin types. Oral involvement is common and its appearance is the same in all skin types – white Wickham’s striae visible on the buccal mucosa.

Lichen planus: hyperpigmented lesions
on the lower leg

^{(Image credit: Dr Nigel Stollery)}