Radiography shows a combination of erosion (unlike in ankylosing spondylosis) and bone growth (unlike in rheumatoid arthritis) in affected joints. The following radiographic abnormalities are suggestive of psoriatic arthritis:
Arthritis mutilans (ie, "pencil-in-cup" deformities)
Joint-space narrowing in the interphalangeal joints, possibly with ankylosis
Increased joint space in the interphalangeal joints as a result of destruction
Bilateral, asymmetrical, fusiform soft-tissue swelling
Unilateral or symmetrical sacroiliitis
Large, nonmarginal, unilateral, asymmetrical syndesmophytes (intervertebral bony bridges, seen in the image below) in the cervical, thoracic, and lumbar spine, often sparing some of the segments
For more on the workup of psoriatic arthritis, read here.
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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this: Herbert S. Diamond. Fast Five Quiz: How Much Do You Know About Psoriatic Arthritis? - Medscape - Jun 13, 2016.