Psoriasis is easily cured by changing your diet. It is caused by eating a low fat diet. Biologics etc are not required.
A high fat keto diet will get rid of it.
In brief; Stop eating cereals, legumes and other starchy foods. Eat fruits, herbs, spices and cooked free range animal foods. Fats are NZ butter, palm, soy bean, sunflower, sesame, perilla oils. These are to be eaten with the cooked animal foods. If you are used to eating dairy, add NZ Mainland Vintage cheddar or other fermented free range cheeses, otherwise avoid dairy (not butter). Drinks fruit juices, mineral water, teas, coffees, chocolate, coconut milk, nut milks etc. Eat one meal a day and 50-70g fat.
Local free range animal foods... village pork, village chickens & eggs, rice field ducks & eggs, wild fresh water fishes. DO NOT eat beef. Now is the time to eat Tilapia from your local lake/river as they are very fat in the rainy season.