The prevalence of dermatomyositis is higher in people with dark skin. After analysing 100 cases published since 1951, Canadian authors note that for this population:
- the initial diagnosis is incorrect in 10% of cases, with myositis being confused with hypertrophic lichen planus, an allergic reaction, a skin infection, etc.
- dyschromia (hypo- or hyperpigmentation), associated in particular with Gottron’s papules and heliotrope eruptions, is more common than erythematous presentations of the disease,
- perionychial microvascular lesions may be underdetected due to the difficulty of visualising capillaries on darker skin.
