Many patients and even doctors do not know what kind of disease dermatomyositis Gottron’s sign is. Some think it is dermatological, some say it is orthopedic, and some think it is neurological or infectious. In fact, dermatomyositis Gottron belongs to the category of autoimmune diseases, and is a rheumatological disease. The Gottron sign of dermatomyositis manifests as diffuse inflammation of skin and muscle, with erythema and edema of the skin and muscle weakness, pain and swelling, which may be accompanied by arthralgia and multiple organ damage such as lung and heart muscle; while polymyositis has no skin damage. The skin and muscle are the two main groups of symptoms, and the skin often precedes the muscle by weeks to years, or it can be preceded by myositis or the muscle and skin at the same time. Skin and muscle symptoms often do not parallel each other, and one can be very severe while the other is mild. In individual cases, the first organ to show symptoms may not be the skin or muscle, but the heart, lungs or pleura, manifesting as pericardial tamponade, pulmonary fibrosis or pleurisy. 1. Skin symptoms Typical lesions are edematous purplish spots on both upper eyelids, spreading to the periorbital area and gradually expanding to the face, neck and upper chest V-zone. The skin is typically a purplish papule with dilated capillaries, hypopigmentation, and fine scales on the elbows and knees of the extremities, especially between the metacarpophalangeal and phalangeal joints, called Gottron’s sign. The edematous purplish spots on the upper eyelids and Gottron’s sign are important in the diagnosis of dermatomyositis, especially the former, which appears earliest and is significant for early diagnosis. The rash is painless and pruritic in most patients. Other skin lesions of dermatomyositis are heterochromia, erythroderma, cutaneous vasculitis, urticaria, and calcium deposits. The possibility of skin heterochromia with malignancy increases; those with cutaneous vasculitis are prone to have systemic vasculitis at the same time, often with severe symptoms and poor prognosis when not treated properly; those with cutaneous calcium deposits often have mild damage to important organs and a better prognosis. 2, muscle symptoms Involvement of transverse muscle, but the involvement of skeletal muscle is much more common than the heart muscle; smooth muscle is rarely involved. The proximal muscles of the extremities are most vulnerable, such as the deltoid and quadriceps. The onset is mostly symmetrical. The lesioned muscles have symptoms such as weakness and pain, and show corresponding movement disorders, such as difficulty in raising the upper limbs, inability to lift the lower limbs and inability to rise after squatting; in more severe cases, difficulty in raising the head and inability to turn over, showing the involvement of the cervical and trunk muscles. The involvement of esophageal and pharyngeal muscles may cause difficulty in swallowing, coughing and choking after eating, and change in pronunciation. Shortness of breath and dyspnea may occur with respiratory muscle involvement. The eye muscles may be involved with diplopia. A small number of patients may not have myalgia and only show muscle weakness. 3, other system symptoms (1) digestive system: digestive tract symptoms are the most common among the system damage, manifested as abdominal distension, reduced appetite, digestion and malabsorption, constipation or diarrhea. Nearly 1/3 of patients have difficulty swallowing; abnormal liver function is more common when the disease is active. Individual patients may have gallbladder sclerosis and cholestatic hepatitis, when anti-mitochondrial antibodies can be detected. (2) Respiratory system: common pulmonary lesions are: interstitial pneumonia with an incidence of >40%; alveolitis (>30%) and ventilation disorders due to bronchopneumonia (about 20%). It mostly develops slowly, can have varying degrees of dyspnea, and is prone to secondary infections. Non-invasive early examination of lung lesions can be performed with high-resolution CT and pulmonary function tests. Pulmonary function tests are the most sensitive in terms of carbon monoxide diffusion function tests, which can detect early stage patients with still unchanged imaging, especially alveolitis. In a small number of patients, interstitial lung lesions appear in an acute form, manifesting as acute fever, dyspnea, cyanosis, and dry cough, while symptoms of muscle weakness may not be obvious, and respiratory failure may appear sooner, with a poor prognosis. Pleurisy can sometimes occur; pneumothorax, mediastinal pneumothorax and even extensive subcutaneous emphysema can also occur in some cases. (3) Heart: Cardiac lesions are more frequent, and about 50% of them are found to be abnormal, but most of them are mild, and only the electrocardiogram shows ST-T changes. Others include arrhythmias and different degrees of conduction block. Very few patients have heart failure and severe arrhythmias due to cardiomyopathy, and then the prognosis is poor. (4) Kidney: renal lesions are mild and rare, there may be a small amount of proteinuria, tubular urine and hematuria. (4) Malignant tumors 25% of patients are prone to develop tumors, which can occur before the appearance of myositis, at the same time, or after it. Common types of tumors include: lung cancer, stomach cancer, breast cancer, nasopharyngeal cancer and lymphoma.