Psoriasis is mainly divided into four types a. Common psoriasis 1. More than 99% are common psoriasis, and wax droplet phenomenon, film phenomenon and punctate bleeding can be seen. 2.Psoriasis vulgaris is divided into three stages according to the development of the disease. a.Progressive stage: old skin lesions do not fade, new skin lesions appear constantly, infiltrative inflammation of skin lesions is obvious, there can be a red halo around, thicker scales, there can be homomorphic reaction (Kobner phenomenon); b.Static stage: stable skin lesions, no new skin lesions appear, inflammation is light; c.Regressive stage: skin lesions shrink or flatten, inflammation basically subsided, leaving hypopigmentation or pigmentation c. Degenerative stage: lesions shrink or flatten, inflammation basically subsides, leaving hypopigmentation or pigmentation spots. In addition to skin lesions, joint lesions may appear, usually with skin lesions first, followed by joint symptoms. Erythrodermic psoriasis is characterized by diffuse flushing, infiltration and swelling of the skin with a large number of branched scales, during which there may be patches of normal skin (skin islands), accompanied by systemic symptoms such as fever and enlarged superficial lymph nodes. The course of the disease is long, and after receding, common psoriasis lesions may appear, which are easy to recur. Pustular psoriasis: There are two types: generalized and limited.