Psoriasis, also known as “psoriasis”, is a common and recurring chronic inflammatory skin disease. The cause of psoriasis is not completely clear and there are many theories, mainly genetic, immune dysfunction, infection, and metabolic disorders. In addition, mental trauma, trauma, surgery, menstruation, pregnancy and food can be triggering factors or aggravate the lesions. Chinese medicine is called “Bai Xuan”, “Xuan Feng”, etc. 1. Clinical manifestations 1. The initial inflammatory flat papules are pinhead to lentil in size, gradually increasing to coins or larger light red infiltrated spots with clear boundaries, covered with multiple layers of silvery white scales. Gently scrape away the surface scales, then a layer of light red shiny translucent film, called film phenomenon. Scrape the film again, there will be small bleeding spots, called dotted bleeding phenomenon. 2.During the development process, the lesion form can be manifested in various forms. In the acute stage, the lesions are mostly dotted, bright red and itchy. The resting lesions are often plaque-like or map-like. The fading lesions are often annular or semi-annular in shape. The scales on a few rashes are thicker and sometimes pile up like shell oyster. 3. The lesions can occur symmetrically in any part of the body. It is more likely to occur on the elbow, knee joint extension and head. Finger (toe) nails and mucous membranes can also be invaded in a few patients. 4.Patients with psoriasis secondary to erythroderma are called erythrodermic psoriasis; the rash with a small amount of exudate, with wet scales, or initially small pustules, accompanied by fever and other symptoms are called pustular psoriasis; combined with joint lesions are called arthritic psoriasis. 5.The disease has an acute attack and a chronic course with a tendency to recur. The onset of the disease is often related to the season, there are those who increase in summer and heal themselves in autumn and winter; there are also those who relapse in winter and spring and reduce in summer. Diagnosis 1. The diagnosis can be made based on the clinical features of the disease. 2, need to distinguish with seborrheic dermatitis, pityriasis rosea. The seborrheic dermatitis damage is more yellow-red follicular papule with indistinct boundary, covered with greasy bran-like scales. Rose pityriasis typical lesions for oval yellow-red macules, surrounded by rose-colored dyke-like elevation, macules on the attached gray-white ring bran-like scales, most often on the trunk and the proximal extremities, can be self-healing.