Additional Study Information: We are looking for patients who have been diagnosed with Psoriatic Arthritis (PsA) to help us better understand the involvement of inflammation on the body. With a combination of bloodwork, a bone density scan, questionnaires, and a one-time soft tissue biopsy (from an area around the belly button), we hope to see how PsA interacts with these multiple areas of physiology. A second visit four months later will be the same as the first visit (except for the tissue biopsy).