What radiographic features help to differentiate Psoriatic arthritis from other inflammatory diseases?
Historically, 45% to 50% of patients will develop erosions within the first 2 years of their disease, and 67% will eventually develop radiographic changes. Some relatively unique findings in PsA include:
- • Asymmetric distribution; involvement of DIP joints
- • Eccentric erosions, periostitis, and bony ankylosis
- • Relative absence of periarticular osteopenia
- • Whittling of the phalanges, pencil-in-cup deformity, osteolysis of bones (arthritis mutilans), and erosion of the terminal tufts (acroosteolysis)
- • Polyarticular unidigit—metacarpophalangeal, proximal interphalangeal (PIP), and DIP of same finger involved
- • Erosions at entheseal sites
- • Musculoskeletal ultrasound and/or magnetic resonance imaging showing signs of enthesitis and dactylitis
- • Sacroiliac and spondylitic changes (usually asymmetric).
