1.What is psoriasis? Psoriasis, also known as psoriasis, is a chronic skin disease characterized by erythematous scales, which is confined to a certain part of the skin for a long time or spreads all over the body. 2, the types of psoriasis and clinical manifestations? ( 1 ) common psoriasis: the lesions are initially light red or red papules or rashes, showing multiple layers of milky white scales, scraping away the scales can reveal shiny film, scraping away the film is point-like bleeding. The initial damage is mostly in the form of droplet-like papules, the number of which is small but large, and it can spread all over the body in about one month, which is called punctate psoriasis. If the spots keep increasing or fusing with each other to reach coin-shaped or larger plaques, they are called coin-shaped or map-shaped according to their shape. The scalp damage is clearly defined and the hair is in bundles, but it does not fall off. The finger (toe) nail surface may be needle-like depressed or uneven, or it may become yellow and thickened. The nail plate is separated from the nail bed, and its free line is either broken or buckled. ( 2 ) Joint psoriasis: In addition to skin lesions, patients may also have joint lesions. Any joint can be involved, some patients only invade the distal finger (toe) joints, single or several joints are involved at the same time or successively, and there may be joint deformity. Most cases involve the distal finger (toe), wrist, ankle, knee, elbow and hip joints. There may be swollen or painful joints and restricted movement, which will return to normal or become deformed later, similar to rheumatoid arthritis. ( 3 ) Erythrodermic psoriasis: Mostly caused by the external use of strong irritating drugs in the progressive stage, or by the internal use of arsenic, hydroquinone, etc. to stimulate the rapid spread of skin, resulting in this type of lesions, some are due to the process of taking hormones. It can also develop from the progressive stage. The patient’s skin remains normal with clear borders like islands and hyperkeratosis of the palms and toes, often accompanied by fever and arthralgia. ( 4 ) Pustular psoriasis: lesions can be limited to the stimulation site, on the basis of psoriasis damage, the occurrence of clusters, rice grain large pustules, the base flushed, and some even generalized throughout the body, pustules superficial, yellow-white, pus is not much, sooner that dry crust, new pustules appear one after another around. 3, psoriasis is caused by what factors? ( 1 ) genetic factors: the form of heredity may be the recessive inheritance of both parents’ chromosomes. It may also be that Mendel’s simple chromosomes show the law of inheritance and have incomplete manifestations of heredity, such as one of the two parents suffering from psoriasis whose children have a higher incidence. ( 2 ) Triggering and aggravating factors: environmental and climatic factors, mental and emotional factors, trauma and infection factors, endocrine factors, drugs and vaccination are often triggering and aggravating factors of the disease, such as drug allergy.