Anteroposterior radiograph of the hands shows subchondral erosions of the fourth left distal interphalangeal joint and right third and fourth proximal interphalangeal joints with periosteal reaction. Courtesy of Bruce M. Rothschild, MD

Anteroposterior radiograph of the feet shows arthritis mutilans. Courtesy of Bruce M. Rothschild, MD.

Anteroposterior radiograph of the thumb shows arthritis mutilans. Courtesy of Bruce M. Rothschild, MD.

Anteroposterior radiograph of the pelvis in a male patient shows sacroiliitis in association with psoriasis. Courtesy of Ali Nawaz Khan, MBBS.

Left, lateral radiograph of the dorsal spine of a 38-year-old man shows spondylitis in association with psoriasis. Note the squaring of the anterior vertebral bodies. Right, radiograph of the pelvis in the same patient shows sacroiliitis and erosive changes around both hip joints. Courtesy of Ali Nawaz Khan, MBBS.