Psoriatic arthritis.

Although there is still some controversy about the existence of psoriatic arthritis (PsA) as a specific form of inflammatory arthritis associated with psoriasis, epidemiological and clinical studies support the unique features of PsA. Because of lack of diagnostic or classification criteria, the disease has been thought of as uncommon. New classification criteria should facilitate case definition of PsA. Over the past several decades, it has become clear that the disease leads to serious disability and even increased mortality. Traditional medications have not been effective in preventing the progression of joint damage. New medications, including biologics, have emerged with potential to controlling the inflammation and arresting the progression of joint damage.