Dermatomyositis is associated with several pathognomonic rashes. Gottrons papules are pink, popular lesions found in a characteristic distributionthe extensor surfaces of the hands (which can be accentuated over the joints) and other areas, such as the elbows and knees. The heliotrope rash of dermatomyositis is also pathognomonic and is a bluish rash most commonly found over the eyelids. Also commonly found in dermatomyositis, although not pathognomonic, are periungual erythema, characterized by capillary loop dilation and fallout on capillary microscopy, and a dramatic rash in sun-exposed areas (called the shawl sign with neck and anterior chest involvement, resembling severe sunburn). A diffuse sandpaper-like rash is seen in scarlet fever. Urticarial lesions are seen in infection (eg, acute hepatitis B), in an allergic response, and in connective tissue disease/vasculitis. Hyperpigmented, hyperkeratotic lesions are seen in discoid and systemic lupus erythematosus. Petechial rashes can be seen in small vessel vasculitis and in a number of infections. Distribution of the rash is helpful but not entirely diagnostic. In small vessel vasculitis, such as Henoch-Schšnlein purpura, lesions tend to occur in a gravity-dependent fashion.
- Pink, popular lesions found on the extensor surfaces.
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Seminars in Medical Practice
Hospital Physician Board Review Manuals
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