The psoriasis is a disease of the skin type of inflammatory, naturally a turnover occurring. It is a chronic progressive condition, but its course could be unpredictable with acute phases and remissions. The causes of psoriasis are not fully known, but some evidence suggests that there is a component that is mediated by abnormal T lymphocytes. Even environmental factors play a role and it was determined that in some cases, factors such as emotional stress or infection may induce the expression of the first episode of psoriasis and may also cause relapses.
The psoriasis may be caused or aggravated by drugs like lithium, chloroquine, hydroxyl chloroquine, beta-blockers, ACE inhibitors and NSAIDs.
The most common form of psoriasis (80%) is the chronic plaque, characterized by well-demarcate plates, often distributed in a symmetrical, inspessite, and red chips. It presents a great variability in the size and number of plates, one or two chips to cover 100% of the body surface. The plaques may occur in any paragraph of the skin, but is typically found on the extensor surfaces of the knee and elbow and the scalp. It is estimated that 5-7% of people with psoriasis and 40% of those with extensive skin disease develop inflammation of the joints known as psoriatic arthritis.