All systems of the body are involved, but the more common are the oral cavity, skin, genitalia and eyes, and the central nervous system, blood vessels and gastrointestinal tract are heavily affected, and the incidence is higher in men. Japanese scholars reported that the incidence of damage to each organ system was 100% for oral ulcers, 90% for skin rashes, 97% for external genital ulcers, and 79% for eye damage. The incidence of eye damage was higher in males than females, with 90% and 40% respectively. Other systemic damage was 28% in the central nervous system, 20% in the digestive system, 15% in the cardiovascular system, and 15% in the joints. In a small number of patients, the onset of the disease is acute and can occur simultaneously in two or more sites within 5 days to 3 months, and the disease is severe and often accompanied by high fever. After a certain period of remission, the disease may recur chronically, with an average time between recurrences of 1 to 2 months. Most of them have chronic onset, with damage occurring in one site first, and then in other sites after different periods of recurrent attacks and remission. The latter is predominantly localized, with fewer systemic symptoms, but can worsen acutely during the course of the disease. The main systemic symptoms are high fever, headache, fatigue, loss of appetite, and joint pain or swelling, both in acute attacks and in acute exacerbations during the chronic course of the disease. The fever pattern is variable, and in a few cases, the fever may be persistent. Excessive fatigue, poor sleep, menstruation, and seasonal climate changes can aggravate the damage in different areas. Basic symptoms: These are the most common and often the earliest symptoms in the disease. They can appear one after another or simultaneously over a period of up to several years. Most have an insidious onset, while a few have an acute onset and are accompanied by systemic symptoms such as fever and malaise. 1, recurrent oral ulcers: at least 3 episodes per year, during which more than one painful red nodule appears on the buccal mucosa, lip edge, lips, soft palate, etc. followed by ulcer formation, the diameter of the ulcer is usually 2-3 mm. some start with a herpes, which will subside on its own after about 7-14 days without leaving a scar. There are also cases that do not heal for several weeks and end up with scarring. The ulcers are repeated. This symptom is seen in 98% of patients and is the first symptom of the disease. It is considered the most basic and necessary symptom for the diagnosis of the disease. 2. Recurrent vulvar ulcers: The symptoms are basically similar to those of oral ulcers, except that they occur less frequently and in smaller numbers. The common sites are the labia majora and minora in female patients, followed by the vagina; and the scrotum and penis in males. It can also appear around the perineum or anus. About 80% of patients have this symptom. A small number of patients have a family history and there are no cases of contact transmission. 3, skin lesions: skin mucosal damage is a major symptom of the disease, accounting for 95.7%. There are four kinds of skin damage as follows: ① erythema nodosum: It is the most common kind of skin damage, mainly in the lower extremities, especially the lower legs, and sometimes also in the upper extremities and trunk, with the extensor side being the most common. The subcutaneous nodules are generally bean to walnut in size, varying in depth, with pain and pressure, and the skin is light red, dark red or purple-red in color, with a hard texture. The nodules may fade on their own within a month or so, but are prone to recurrence. It may fade on one side and develop on the other side. Most of them are heavy in summer and rarely break down. Some of the nodules can be red in color beyond the nodule area, and the color becomes lighter as it goes outward, seemingly surrounded by a red halo. ②Thrombophlebitis: It occurs mainly in the lower extremities, sometimes also in the upper extremities, and is a hard subcutaneous cord with local pressure pain. If it occurs deep under the skin, only subcutaneous cords are felt on physical examination; if it occurs in superficial subcutaneous veins, there may be varying degrees of skin surface redness and elevated skin cords. Superficial thrombophlebitis can also occur secondary to intravenous drug injection. (iii) Folliculitis-like and boil-like lesions: More males than females have folliculitis-like lesions than boil-like lesions. These lesions can occur anywhere on the body surface, mostly on the head, face, chest and back, and pubic area. The lesions vary in number and can be recurrent, with summer being the most severe. These lesions have a more prominent basal infiltrate, fewer apical pustules, and a larger surrounding redness with varying degrees of sclerosis. Bacterial cultures are negative and antibiotic treatment is ineffective. The reddish papules with pustules in the center can be produced at the site after 24-48 h. This reaction is called needle reaction. In the active stage of the disease, it is mostly positive and has specific diagnostic significance. Sometimes the needle prick reaction is negative, when injected with saline, generally in 24h after the needle prick site can appear pustules. It must be emphasized that even if the needle prick reaction is negative, it cannot exclude leukoplakia. 4, eye damage: ocular symptoms as the main manifestation of leukoaraiosis, also known as ocular leukoaraiosis, which is mainly characterized by transient, regressive exudative inflammation. All tissues of the eye can be involved, the early manifestations are keratitis, conjunctivitis, scleritis and iridocyclitis with pus accumulation in the anterior chamber. After repeated attacks, the main manifestations are chorioretinitis, uveitis, retinitis, fundus hemorrhage and vitreous clouding, which can lead to blindness as the disease progresses. Ocular damage can be unilateral or bilateral. Conjunctivitis, keratitis, and sclerositis all result from a combination of inflammatory chemical irritation or other harmful factors leading to impaired blood circulation on top of vasculitis. Conjunctivitis also presents with regressive episodes, with each episode lasting 3 to 5 days. It may be accompanied by varying degrees of keratitis. Prolonged attacks often result in corneal ulceration and even corneal perforation. Sometimes secondary cataracts can develop on the basis of repeated episodes of conjunctivitis and keratitis. Typical iridocyclitis with anterior chamber pus accumulation is not uncommon. The anterior chamber pus accumulation is aseptic and has a neutrophilic cellular component with a small amount of fibrin. The leukocytes are mainly from the inflamed iris. Retinitis is characterized by acute regressive episodes that manifest as redness and clouding of the optic disc, retinal white spots, and hemorrhage. Vitreous turbidity is one of the main manifestations of ocular damage in this disease and can be exacerbated by each episode, with this change preceding anterior chamber clouding. Vitreous turbidity is caused by inflammatory exudation from the surrounding capillaries. Exudate from the radial capillaries surrounding the papillae connected to the vitreous lining can easily enter the vitreous, irritate the lining and form granuloma tissue. Similarly, granuloma tissue may form around the area connected to the choroid of the posterior ciliary ring. Granuloma formation at the vitreous and posterior ciliary ring choroid is the main factor causing vitreous clouding.