It is more frequent in Caucasians of Northern European origin



-Psoriasis is a common skin condition which affects about 2% of the population.
-It is more frequent in Caucasians of Northern European origin.

-Its classical (vulgaris) presentation consists of erythematous plaques located on the extensor areas such as the elbows, knees buttocks and the scalp.
-Old lesions can sometimes show lesions (Koebner phenomenon)
-The disease is classically non itchy however in up to a third of cases, scratching is a common complaint.
-It is sometimes associated with a change of the tongue: geographic tongue

-Scraping of the lesions produces pinpoint bleeding (Auspitz sign).
-Nail changes are usually also found (irregular nail pitting, onycholysis, “oil spot”, rough surface)

-Other forms are called inverse psoriasis, guttate psoriasis, pustular psoriasis and palmoplantar psoriasis

-Causes are partially known and genetic factors only explain part of the problem. Indeed in monozygotic twins, if one is affected, the other twin is only affected in 70% of the cases.
-Psoriasis is described as been associated with the metabolic syndrome which includes hypertension, obesity, diabetes and hyperlipidemia.
Treatment options include:
-topical steroids
-oral acitretin, methotrexate, ciclosporin, apremilast
-biologics (etanercept, adalimumab, infliximab, secukinumab…)