Many people experience rashes in their daily lives. In the general perception, rashes are lesions of the skin, and therefore, rash attacks fail to attract widespread attention. In fact, some rashes are caused by systemic diseases, and changes in the skin are only an external manifestation. It is clear that acute infectious diseases, tumors, and rheumatic-immune diseases can cause rashes and have a variety of manifestations. Rheumatic immune diseases are diseases that tend to involve multiple systems, and many rheumatic diseases have skin damage, sometimes skin damage is even the first symptom of the disease, and sometimes skin damage is a sign of disease activity. For example, patients with SLE may develop discoid erythema, often on the face, which appears as a well-defined purplish-red infiltrate, and may have hyperpigmentation or hypopigmentation after the lesions fade. SLE may also present with erythema nodosum, which presents as a painful red rash with subcutaneous nodules, or various forms of skin damage such as erythema multiforme and reticulocutaneous cyanosis. Dermatomyositis is an inflammation of the skin, skeletal muscles and small blood vessels, mainly manifested by characteristic skin lesions and proximal muscle weakness of the extremities. The characteristic rash of dermatomyositis is a purplish-red patch around the orbit, purplish-red patch on the face, forehead and anterior V-row area of the neck, which may be accompanied by itching sensation. Patients with malignancy are prone to dermatomyositis, and these patients may have bright flame-like erythema on the face and neck. Scleroderma is a common clinical autoimmune disease characterized by fibrosis and sclerosis of the skin and internal organs. The prominent features of the lesions are hardening of the skin on the hands, forearms, face and trunk, and coexistence of hyperpigmentation and hypopigmentation. Most of the patients have Raynaud’s phenomenon, i.e. the skin of fingers turns white when cold, purple when warm, and then red. The main clinical manifestations of dry syndrome are dry mouth, dry eyes, dry skin, and in severe cases, damage to the lungs and kidneys. Some patients may develop purpura-like lesions, petechiae, petechiae and palpable purpura, which are sometimes misdiagnosed as allergic purpura. The rash manifestation of rheumatic diseases is complex, while some malignant tumors may also present with rashes similar to erythema nodosum and purpura-like rashes. Therefore, clinical concomitant symptoms are important for disease diagnosis, but since the same rash can appear in multiple diseases, laboratory tests should not be neglected even more. For some patients with normal autoimmune index, further skin biopsy is needed to determine the nature of lesions and exclude Malignant tumors. The treatment and prognosis of different causes of rash are completely different, for example, if it is only a simple skin lesion, only local medication is needed, and in severe cases, internal medication can be used in conjunction with it, but the overall prognosis is good. If the rash is caused by a rheumatic immune disease, it should be treated with glucocorticoids and immunosuppressants, and at the same time, the rash and the disease should be controlled with Chinese medicine. or so. Therefore, the appearance of clinical rash deserves the attention of both patients and doctors. Of course most rashes are only predominantly simple skin lesions, but some patients will develop other autoimmune disease manifestations over several years, eventually confirming the diagnosis of a particular systemic disease. Whether simple or concomitant with other diseases, the appearance of skin lesions should be promptly diagnosed and treated to exclude rheumatic and malignant diseases, which has positive implications for improving the quality of life of patients.