Joint pain, stiffness and swelling are the main symptoms of psoriatic arthritis. They can affect any part of your body, including your fingertips and spine, and can range from relatively mild to severe. In both psoriasis and psoriatic arthritis, disease flares may alternate with periods of remission.soriatic arthritis is a form of arthritis that affects some people who have psoriasis — a condition that features red patches of skin topped with silvery scales.