Psoriatic arthritis is a chronic disease of the joints. It most often occurs with the skin disease, psoriasis. About 30 percent of people with psoriasis also experience psoriatic arthritis. The symptoms of psoriatic arthritis include joint swelling, stiffness (common in the morning), burning and pain. Nail pitting can also be associated with psoriatic arthritis. Fingers, toes, and the spine are common areas affected the disease. Symptoms can be mild or severe and can vary by week, month or year.