Psoriatic arthritis is a chronic inflammatory joint disease associated with psoriasis.

It is a seronegative inflammatory arthritis differentiated from rheumatoid arthritis (RA) by several clinical features. These include:

• a frequent oligoarticular or monoarticular initial pattern of joint involvement, as well as distal interphalangeal joint (DIP) involvement.
• Asymmetrical presentation
• Dactylitis, a fusiform swelling of an entire digit, and sacroiliitis are manifestations not observed in RA.
• Over time, many patients will progress to a polyarticular pattern of joint involvement with erosive arthritis.

Risk factors:

• Psoriasis - Occurs in 10-20% of patients with psorasis
• Family hx of psoriasis or psoriatic arthritis

PC

*Presence of risk factors

• Joint pain or stiffness - prolonged morning stiffness >30 mins
• Peripheral arthritis, 5 main patterns of joint involvement:
  • distal arthritis
  • assymetric oligoarthritis (60%)
  • symmetric polyarthritis
  • spondyloarthirits
  • arthritis mutilans
• dactylitis - uniform swelling of an entire digit
  • Other cause of dactylitis - reactive arthritis
• Hx of scalp or nail problems

Examination:

• late sign - Spinal stiffness (modified Schober test)