Psoriatic arthritis

Related Subjects: | Monoarticular arthritis | Polyarticular arthritis |Seronegative Spondyloarthropathies |Ankylosing spondylitis |Enteropathic Spondyloarthritis |Reactive Arthritis

Psoriatic arthritis is seen in those without HIV but a severe form of psoriatic arthritis is seen in HIV positive patients

About

• Seronegative Spondyloarthritis (Rheumatoid factor negative)
• Arthritis may precede the rash by many years
• The psoriatic rash may predate or follow the onset of the arthritis

Aetiology

• Psoriatic arthritis affects women and men equally
• Genetic predisposition plays a major role
• Immune-mediated mechanism
• Exogenous trigger factors can play a significant role

Pencil in cup deformity on 5th toe

Clinical

• Skin: look for the classical scaling erythematous silvery psoriasis rash may be seen.
  • Plaques on Scalp
  • Extensor Surfaces (elbows, knees)
  • Umbilicus, Natal Cleft
  • Palms and Soles
  • Lower Back
• Joint arthritis patterns
  • Asymmetrical small joints of the hands especially DIP joints
  • Symmetrical and mimic RA.
  • Destructive arthritis mutilans
  • Dactylitis: inflammation of the whole finger, red swollen tender "sausage digit"
  • Nail pitting and onycholysis (lifting of nail from the nail bed) and oil drop sign due to discolouration, pitting, onycholysis, yellowing and ridging
  • Enthesitis (inflammation where tendon/ligament insertion) - most commonly affects Achilles tendon.
  • Sacroiliitis: spinal stiffness and inflammatory back pain
• Lungs: Pulmonary fibrosis
• Cardiac: Aortic regurgitation
• Eyes: Conjunctivitis and Anterior uveitis often with spinal involvement

Typically five joint involvement patterns

• Distal interphalangeal form with nail changes
• Asymmetrical mono/oligo arthritis - like a spondyloarthropathy
• Symmetrical polyarticular arthritis - like rheumatoid
• Arthritis mutilans (rare) with large and small joint destruction
• Axial - sacroiliitis ( like ankylosing spondylitis)

CASPER Diagnostic Criteria

• Inflammatory joint and/or back pain
• Minimum score 3 points from criteria below:
  • Skin psoriasis that is
    • Present + 2 points
    • Previously present +1 point
    • No rash but family history of psoriasis + 1 point
  • Nail lesions (onycholysis, pitting) + 1 point
  • Dactylitis (present or past, documented by a rheumatologist) + 1 point
  • Negative rheumatoid factor (RF) + 1 point
  • Juxta-articular bone formation on radiographs (distinct from osteophytes) + 1 point

Investigations

• FBC:anaemia. ESR/CRP: Normal or Elevated
• Seronegative: RF and anti-CCP negative, ANA negative
• Radiographs of the hands and wrists (AP view), feet (AP and lateral views) and all symptomatic sites (including axial sites) may aid diagnosis. Identify joint erosion, joint space narrowing, bony proliferation including periarticular and shaft periostitis, osteolysis including "pencil in cup" deformity and acro-osteolysis, ankylosis, spur formation and spondylitis.

Management

• Patient education, Stopping smoking, Analgesia with NSAIDs, Physiotherapy
• Sulfasalazine, Methotrexate, Biological Anti-TNF alpha agents
• Splinting, Joint surgery and replacement

References

• Psoriatic arthritis: a review