Erosive arthritis (differential)

Erosive arthritis has a broad differential:

• erosive osteoarthritis

  • clinically an acute inflammatory attacks (swelling, erythema, pain) in postmenopausal women

  • 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 synovioentheseal 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

  • 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.

• 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 (e.g. tenosynovial giant cell tumors, synovial osteochondromatosis)

• articular defects simulating erosions in CPPD, osteonecrosis, osteochondritis dissecans, and osteochondral fractures

• septic arthritis: mono-articular

• neuropathic (Charcot) arthropathy