Psoriatic arthritis (PsA) is an inflammatory arthropathy associated with psoriasis, with a psoriatic rash that causes pain, swelling, tenderness, stiffness and movement disorders in the joints and surrounding soft tissues, and some patients may have sacroiliac arthritis and/or spondylitis, with a prolonged, easily recurring course and joint ankylosis in advanced stages, leading to disability. About 75% of patients with PsA have a rash that appears before arthritis, about 15% have it at the same time, and about 10% have it after arthritis. The disease can occur at any age, with a peak age of 30 to 50 years, with no gender differences, but spinal involvement is more common in men. In the United States, the prevalence of PsA is 0.1%, and arthritis occurs in about 5% to 7% of patients with psoriasis. The prevalence of PsA in China is about 1.23‰. Clinical manifestations] The disease starts insidiously, about 1/3 of them have acute attacks, and there is often no cause before the onset of the disease. 1, joint manifestations (1) a variety of joint symptoms In addition to peripheral joint lesions of the extremities, some may involve the spine. Pain, pressure, swelling, morning stiffness and dysfunction of the affected joints are divided into five types according to clinical characteristics, and 60% of the types can be transformed into each other and exist together. (2) Monoarthritis or oligoarthritis type (70%), mainly in the distal or proximal interphalangeal joints of the hand and foot, but also in the knee, ankle, hip and wrist joints, with asymmetric distribution. (3) Distal interphalangeal arthritis type (5%-10%), involving the distal interphalangeal joints, is typical of PsA and is usually associated with psoriatic nail lesions. (4) Disfiguring arthritis type (5%) is a serious type of PsA, with a predilection for age 20-30 years. The affected finger, metacarpal and metatarsal bones may have osteolysis, the knuckles may be telescopically overlapping, and the joints may be straight and deformed. It is often associated with fever and sacroiliac arthritis, and severe skin lesions. (5) Symmetrical polyarthritis (15%), the lesions are mainly in the proximal interphalangeal joints, but may involve the distal interphalangeal joints and large joints such as wrist, elbow, knee and ankle joints. (6) spondyloarthropathy type About 5%, male, older people are more common, mainly spine and sacroiliac joint lesions, often unilateral, lower back pain or chest wall pain and other symptoms can be absent or very light, spondylitis manifested as ligamentous redundancy formation, in serious cases can cause spinal fusion, sacroiliac joint blurring, joint space narrowing or even fusion, can affect the cervical spine leading to atlantoaxial and subaxial incomplete dislocation. 2, skin performance According to the clinical characteristics of psoriasis, it can be generally divided into four types: common, pustular, arthritic and erythrodermic. The skin psoriasis lesions are usually found on the scalp and the extremities, especially the elbows and knees, with scattered or generalized distribution, and special attention should be paid to the lesions in hidden areas such as hair, perineum, buttocks and umbilicus, etc.; the lesions appear as papules or plaques, garden-shaped or irregular-shaped, with abundant silvery-white scales on the surface, and shiny film after removing the scales, and dotted bleeding (Auspitz’s sign) is visible after removing the film, which has diagnostic significance for psoriasis. It has diagnostic significance. The presence of psoriasis is an important distinction from other inflammatory arthropathies, and there is no direct relationship between the severity of skin lesions and the degree of joint inflammation, and only 35% of the two are related. (1) Finger (toe) nail manifestations About 80% of patients with PsA have finger (toe) nail lesions, compared with 20% of patients with psoriasis without arthritis, so finger (toe) nail lesions are characteristic of PsA. The common manifestations are thimble-like depressions, multiple depressions in the nails of the distal interphalangeal joints of inflammation are characteristic changes of PsA. Other changes include thickening of the nail plate, cloudiness, darkening or white nails, uneven surface, transverse grooves and longitudinal ridges, often with keratinous hyperplasia under the nail, and in severe cases, nail peeling. Sometimes spatulate nail is formed. (2) Other manifestations ① systemic symptoms: a few have fever, weight loss and anemia, etc.; ② systemic damage: 7%-33% of patients have ocular lesions such as conjunctivitis, uveitis, iritis and dry keratitis, etc.; <4% of patients have aortic valve incompetence, which is common in the late stage of the disease, as well as cardiac hypertrophy and conduction block, etc.; upper lung fibrosis is seen in the lungs; inflammatory bowel disease may be present in the gastrointestinal tract, and amyloidosis is rare. (iii) Adhesion point inflammation: especially in the Achilles tendon and metatarsal tendon membrane attachment site. Heel pain is a manifestation of attachment point inflammation.