Psoriasis is a chronic disease that causes skin cells to be replaced rapidly. This causes red, itchy, and flaky patches to appear on the skin. It often affects the torso, elbows, and knees, but can happen anywhere. There is no cure for the condition and the condition often happens in cycles. This means it may flare up then subside for a few weeks. The cause is not clear but the immune system is suspected to play a role. The causes of psoriasis are discussed here.
Immune system malfunction
Disruption in how the immune system works may cause diseases like psoriasis. What causes this malfunction is unclear, but genetics and environmental factors are suspected to play a role. The immune system is the body’s defense against infections. The immune system contains a type of cell known as the T-cell. This cell helps in the detection and destruction of harmful germs. In people with psoriasis, these cells target and attack healthy skin cells by accident, causing the skin to produce more skin cells  than normal.