Psoriasis is a common, immune-mediated disease which causes inflammation in the body. It presents as red, scaly, plaques on the skin and can also cause pain and swelling in the joints (known as psoriatic arthritis). The most common sites of skin involvement include the scalp, elbows, and knees. Other frequently involved areas include the hands, feet, trunk (including the folds of the skin), and nails. Though there is no cure, numerous treatment options are available including topical medications, phototherapy, and systemic treatments (oral pills and injectable medications called biologics).