Psoriasis is a common, chronic, autoimmune disease that causes dry, red, scaly patches and flakes to appear on the skin. The rash often goes away for a while, but then it flares up again, often as a result of a trigger, such as stress.
It is thought to happen when the immune system mistakenly starts producing skin cells too quickly.
Psoriasis is a skin disorder that reasons skin cells to multiply up to 10 times faster than usual. This makes the skin build up into bumpy red patches covered with white scales. They can grow anywhere, but most appear on the scalp, elbows, knees, and lower back. Psoriasis can’t be passed from person to person. It does sometimes happen in members of the same family.
Symptoms
Skins cells shed all the time, but in psoriasis, both dead and live cells collect on the skin’s surface, because the replacement process is so fast.
The main symptoms of psoriasis are:
According to the National Psoriasis Foundation:
Types
There are several forms of psoriasis.
Plaque psoriasis
About 80 to 90 percent of people with psoriasis have plaque psoriasis. It appears as raised, inflamed, red lesions, covered by silvery, white scales, generally on the elbows, knees, scalp, and lower back.
Inverse psoriasis
Inverse psoriasis appears in the armpits, the groin, under the breasts, and in other skin folds such as around the genitals, and the buttocks. It first appears as red lesions, generally without the scale associated with plaque psoriasis. It may appear smooth and shiny.
Irritation from rubbing and sweating can make it worse, because of its location in skin folds and tender areas. It is more common in people who are overweight and in those with deep skin folds. It can affect the genital area.
Erythrodermic psoriasis
Erythrodermic psoriasis is a particularly inflammatory form that can affect large parts of the body surface with a fiery redness. Erythema means reddening.
It usually appears on people with unstable plaque psoriasis, where lesions are not clearly defined. There may also be exfoliation, or shedding of the skin, severe itching, and pain.