Psoriasis is a common scaling skin disease which affects around 1 to 2 per cent of the population. Most psoriasis sufferers will develop psoriasis of the scalp at some time, and the condition is both distressing and cosmetically disfiguring. However, psoriasis does not generally cause permanent loss of hair. The precise cause of psoriasis is not known, but it is almost certainly the result of a disorder of the immune system.& nbsp; Confusion can occur with other conditions, and correct diagnosis prior to treatment is essential.