Psoriasis is an autoimmune disorder that affects the skin, causing scaly patches to appear typically on elbows, scalp and knees. It also can spread to include larger areas of the body, states Healthline. The direct cause of psoriasis is not entirely known, but some factors that may play a role in its development are genetics and certain types of infections.
Nearly 3 percent of the world population have psoriasis, states the International Federation of Psoriasis Associations. It is not a condition that can be spread by people. This skin condition can affect anyone at any age. In up to 15 percent of patients with psoriasis, the condition can appear before the age of 10, notes the National Psoriasis Foundations.
There are different types of psoriasis, including plaque, guttate, inverse and pustular psoriasis. Plaque psoriasis appears as red and raised patches of scaly skin, and pustular psoriasis causes the appearance of blisters that contain pus. The cause of guttate psoriasis, which appears as small skin sores, can be an infection. Inverse psoriasis may be due to a fungal infection and manifests as red and irritated patches in areas, such the groin or armpits
Although psoriasis tends to appear on the elbows and knees, it can also affect other areas of the body, including the face, skin folds, nails and genitals. Patients with psoriasis may have a mild, moderate or severe form of this skin condition. If a patient has psoriasis more than 10 percent of his body, this is considered a severe form, states the National Psoriasis Foundation.