When it comes to systemic lupus erythematosus (SLE), many people may think of it as a skin disease, however, in fact, it is an autoimmune disease and is a common disease in rheumatology. ”Systemic” because this disease can involve almost all organ tissues in the body, including hair, skin, blood system, kidney, lung, heart, liver, gastrointestinal tract, nervous system, etc., causing multi-system damage. Erythema”, however, is only an external skin damage of the disease, mainly manifested as discoid erythema and butterfly erythema on the face. Both systemic and erythema are well understood, but why the term “lupus”? The word “lupus” comes from Latin and has two meanings: the first meaning is that the disease causes skin damage on the cheeks or other areas of the skin, which is stubborn and difficult to treat, and the skin is constantly destroyed and even disfigured in advanced stages, thus making the patient’s face look deformed, like a cunning wolf. The second meaning is that this disease is very dangerous, like a fierce wolf, and it is very easy to recur, persistent, unpredictable, and cunning like a wolf. These symptoms should alert you to the possibility of SLE. SLE is an extremely complex disease that can involve multiple organs and systems and tissues, and the onset of the disease is also variable and can start with a certain symptom. Alopecia: SLE patients can show symptoms of alopecia, which can be of various types, such as lupus hair, non-scarring patchy alopecia, diffuse resting alopecia, discoid lupus erythematosus type alopecia, etc. There are often short, broken hair on the forehead, called lupus hair. There is a link between hair loss and disease activity The condition, if active, can result in massive hair loss, leading to thinning hair. Possible causes include autoimmune inflammation, vasculitis, hair dystrophy and dysfunctional hair follicle cycle. 2, skin damage: some research surveys show that about 80% of patients will have skin mucosal damage during the course of the disease, about 40% of patients with skin mucosal damage as the first symptoms of SLE. The main sites of skin damage are the face (59.8%) and the fingers (toes) (32.8%). The facial lesions mainly include butterfly erythema and discoid erythema, which may be the size of a green bean at first, mostly found unintentionally, and may be light red, bright red or dark red in color. Disciform erythema can also appear on the face, mostly round, round-like or irregular, with a size of a few millimeters, or even more than 10 millimeters, with clear borders. The surface of the rash is covered with dilated capillaries and gray-brown adhesive scales, and there are keratinous protrusions on the bottom of the scales, and the dilated hair follicle opening is visible when the scales are removed. Discoid erythema may also appear on the neck, ears, arms and anterior chest. The facial erythema can last for hours, days or weeks and is usually recurrent. The rash usually fades completely without leaving a trace, but may also show hyperpigmentation or varying degrees of capillary dilatation at the site of the rash and, less frequently, atrophy. In addition, red macules, papules, and capillary dilation may occur, either alone or in combination or sequentially, and all parts of the body may be affected. Some patients may be allergic to light and develop a rash after sun exposure. Erythema of the skin around the ends of the fingers and finger (toe) nails occurs in about 20% of patients and is due to vasculitis, which manifests as small infarcts at the tips of the fingers (toes) and can cause ulcers or even gangrene. The aforementioned hair loss also belongs to skin damage. 3, muscle and joint symptoms: joint pain is a common symptom of SLE, which can be accompanied by morning stiffness. For example, finger joints, knee joints, wrist joints, but most of them are not accompanied by redness and swelling. Some patients also have muscle pain and muscle weakness. 1/5 patients have Raynaud’s phenomenon, which appears as the skin becomes pale after the hands are cold, followed by bruising and then flushing. 4, oral ulcers: SLE patients can appear oral ulcers, mostly in the active period, can be single or multiple, generally painless, but some patients will feel painful. The ulcers can occur in the oral mucosa, teeth, hard palate, soft palate, and nasopharynx. It is mainly vasculitis caused by SLE, which causes mucosal damage. 5. Plasmacytitis: It includes pleurisy or pericarditis, which can be clarified by chest X-ray, chest CT or cardiac ultrasound. it occurs in more than 50% of patients, mostly during acute attacks. Patients will feel chest tightness, shortness of breath, chest pain, palpitations, etc. 6. Neurological symptoms: CNS manifestations are complex and varied, including epilepsy, headache, cognitive impairment, mood disorders or psychosis, such as schizophrenia. 7. Problems with routine blood tests: SLE can affect the hematopoietic system. Routine blood tests reveal low hemoglobin (anemia), leukopenia, and low platelets. Patients may experience dizziness, palpitations, bleeding symptoms, and may become susceptible to colds. 8. Problems with routine urine examination: SLE can involve the kidneys and develop lupus nephritis. When urinating, it is found that the urine will be bubbly and foamy, and the routine urine test will find positive urine protein, or find red blood cell tubular, hemoglobin tubular, granular or mixed tubular. When any of the above symptoms appear, you should be alert to the possibility of SLE, and “the wolf may be guessing to approach you”. However, the diagnosis of SLE requires a combination of clinical and examination, and only one symptom is not necessarily SLE, and the above symptoms should also exclude other diseases caused by it. Therefore, it is recommended to seek specialist advice from the rheumatology department whenever possible.