Erosive arthritis (differential)

Erosive arthritis has a broad differential:

• erosive osteoarthritis
  • clinically an acute inflammatory attacks (swelling, erythema, pain) in postmenopausal woman
  • typically the interphalangeal joints, 1^st carpometacarpal joint ⁶, but not the metacarpophalangeal (MCP) joints and large joints
  • classic central erosions (gull-wing appearance); possible ankylosis
• rheumatoid arthritis
  • sometimes rheumatoid factor (RF) positive
  • usually proximal, bilateral and symmetric involvement: metacarpophalangeal joints, proximal interphalangeal joints, and carpal bones; involves the hands before the feet
  • erosions in "bare area", frequently in metacarpophalangeal joints ²
  • periarticular osteopenia and later osteoporosis (both unlike psoriatic arthritis), uniform joint space narrowing, subchondral cyst formation, and subluxations; no new bone formation unlike psoriatic arthritis and reactive arthritis
• psoriatic arthritis
  • commonly involves the hands and there is an interphalangeal predominant distribution in psoriatic arthritis vs. metacarpophalangeal joint predominance in rheumatoid arthritis
  • new bone formation key, not a feature of rheumatoid arthritis ²
  • affects the synovio-entheseal complex, explaining enthesitis, adjacent joint capsule synovitis, and periarticular inflammation ²
  • erosions; classic: "pencil in cup"; osteoporosis is not a feature in psoriatic arthritis
• reactive arthritis (Reiter syndrome)
  • predilection for the lower limb
  • symmetrical involvement of the proximal interphalangeal joints, metacarpophalangeal joints, and carpal bones.
  • osteopenia and then osteoporosis, uniform joint space loss, subchondral cyst formation, subluxations, marginal erosions but no bone formation
• ankylosing spondylitis
• gout
  • erosions with overhanging edges (rat bite erosions)
  • tophi, most commonly involving the 1^st metatarsophalangeal joint, known as podagra
• hydroxyapatite crystal deposition disease (HADD)
  • Milwaukee shoulder
• amyloidosis
• multicentric reticulohistiocytosis
• infectious arthritis
• scleroderma
• pressure erosion (PVNS and synovial osteochondromatosis)
• articular defects simulating erosions in CPPD, osteonecrosis, osteochondritis dissecans, and osteochondral fractures
• septic arthritis
  • single joint
• neuropathic (Charcot) arthropathy