Psoriasis, commonly known as “psoriasis”, is a recurrent, chronic skin disease with characteristic scaly red patches. It is relatively common, with an incidence of 0.1%-3% in the natural population. Its etiology and pathogenesis are still incompletely understood. There are four clinical types of psoriasis: the common type, the pustular type, the arthritic type and the erythrodermic type. 1. Psoriasis vulgaris: It is the most common type of psoriasis in clinical practice. The rash starts as red papules of corn to green bean size, and later expands and fuses, generally occurring on the scalp, trunk, and extremities, and appearing as red papules on the skin, gradually expanding and fusing into patches or plaques with thick silvery-white scales on the surface, irregular in shape, some with a map or island-like appearance some lesions are smaller, more often called full of stars. Appearance of the surface has a thick layer of silvery white scales, scrape off the scales, visible light red shiny film, called film phenomenon. Then scrape the film, the appearance of dewdrop-sized bleeding spots, are the characteristics of the disease, with diagnostic value. 2, pustular psoriasis: divided into generalized and limited. The pustular psoriasis is mostly of acute onset, and can be pustular within a few days to a few weeks to spread throughout the body, first with dense pinpoint-sized potential small pustules, soon fused into a pus lake, often accompanied by high fever, joint swelling and pain and general discomfort, blood tests can see an increase in white blood cells, pustules dry up, followed by desquamation, after the desquamation, there are new pustules appear. The pustular psoriasis is usually confined to the palms and toes, with symmetrical erythema on the palms of both hands and toes, and pinhead-sized to chestnut-sized to small pustules on the erythema: it dries up on its own after about 1-2 weeks, and new pustules appear after desquamation, repeatedly extending, with a stubborn course. 3, erythrodermic psoriasis: a more serious and rare type, this type refers to more than 70% of the body skin is diffuse red, dark red infiltrative lesions, the surface has a lot of furfur-like flakes, sometimes in the armpits, thighs and umbilicus due to swelling and epidermal peeling and exudation, oropharynx, nose and conjunctiva can be congested and red, patients often have fever and chills, headache and general discomfort and other symptoms. 4, arthritic psoriasis: rare, can occur at any age, can occur in large and small joints at the same time, but commonly in the wrist, fingers and toes small joints, spinal joints can also occur. The diseased joints have redness, swelling, pain, severe joint cavities with fluid, swollen skin near the joints with restricted activity, and joint stiffness over time, and in severe cases the joints are seen to be destroyed on X-ray, with fast blood sedimentation, often with fever and other systemic symptoms, but the rheumatoid agglutination factor is negative, arthritic psoriasis, skin damage is mostly accompanied by thick oyster shell-like lesions, or there may be only the erythematous and silvery skin of common psoriasis Damage.