In addition to muscle involvement, dermatomyositis (DM) also has characteristic skin involvement. The common skin lesions of DM include: 1. periorbital rash: This is a characteristic skin lesion of DM, with an incidence of about 60%-80%. It manifests as an edematous purplish rash on the upper eyelid or periorbital area, either unilaterally or bilaterally, and is aggravated by light exposure. This rash can also appear on both cheeks, the bridge of the nose, the neck, the V-shaped area of the forehead and the back of the shoulders (called the shawl sign). 2.Gottron rash: red or purplish papules on the extensor surfaces of joints, especially the metacarpophalangeal joints, interphalangeal joints or elbow joints, with irregular margins or fused into patches, often accompanied by skin atrophy, capillary dilation and hyperpigmentation or hypopigmentation, and occasionally skin breakdown, with an incidence of about 80%. These lesions can also appear in the knee joint extension and inner ankle, etc., the surface is often covered with scales or local edema. This is another characteristic skin damage of DM. 3, perineural lesions: nail root folds can be seen at the capillary dilated erythema or petechiae, nail folds and nail bed with irregular thickening, local hyperpigmentation or pigmentation loss. 4, “mechanic’s hand”: in the palm and side of the finger skin hyperkeratosis, cracks and roughness, similar to the hands of skilled workers engaged in long-term manual operation, so the name “mechanic’s hand”. The thickening, roughness and hyperkeratosis of the skin of the heel may also occur, and such patients are often positive for anti-Mi-2 antibodies. 5, other skin mucosal changes: skin vasculitis and lipofuscinosis are also more common skin damage in DM; in addition, there can be Raynaud’s phenomenon of the fingers, finger ulcers and oral mucosal erythema. Some patients may also have muscle sclerosis, subcutaneous nodules or subcutaneous calcification and other changes.