psoriatic arthritis

1. true psoriatic arthritis (1/3)
2. resembling rheumatoid arthritis (1/3)
3. combination of psoriatic and RA (1/3)

findings:

• no juxta-articular osteoporosis (unlike RA)
• periosteal reaction frequent
• assymetrical destruction of DIP with ankylosis
• resorption of terminal tufts with "pencil in cup" deformity
• ivory phalanx
• destruction of 1st toe IP joint with periosteal reaction and bony proliferation at distal phalangeal base (PATHOGNOMONIC)
• assymetrical syndesmophytes (lower C- to upper L-spine)
• squaring of vertebrae in L-spine
• paravertebral soft tissue calcifications
• bilateral assymetrical sacroiliitis

a/w HLA B-27 antigen, negative rheumatoid factor

© 2002, C.E. Kahn, Jr.
2002-04-18