It is critical to identify rheumatoid arthritis early, as prompt intervention can delay disease progression, and reduce the substantial morbidity and mortality of rheumatoid arthritis.2 A diagnosis of rheumatoid arthritis requires 4 of the following: morning stiffness; arthritis in 3 or more joints; arthritis in the wrist, MCP joints, or PIP joints; symmetric arthritis; rheumatoid nodules; positive rheumatoid factor; radiographic changes.1 This patient has the morning stiffness, arthritis in more than 3 joints, symmetric arthritis, and rheumatoid nodules on her feet (Figure 3).
The most common noninflammatory arthritis is osteoarthritis, which affects 21 million Americans.2 The weight-bearing joints are usually affected, and damage may occur because of trauma or repetitive impact. When the hands are involved, the DIP and PIP joints are more likely to be involved than the MCP joints.
FIGURE 3
Rheumatoid nodules on feet
Diagnostic tests can differentiate between causes
Laboratory tests can help differentiate between conditions causing inflammatory arthritis. Rheumatoid factor is positive in 70% of patients with rheumatoid arthritis, and the antinuclear antibody is invariably positive for patients with SLE. Maturity-onset seronegative synovitis has negative rheumatoid factor and antinuclear antibody tests with marked elevation in erythrocyte sedimentation rate. Polyarticular gout may have increased serum uric acid, and is best diagnosed by demonstrating crystals in the joint fluid.
Laboratory tests are not helpful in diagnosing psoriatic arthritis, seronegative spondylo-arthropathies, and osteoarthritis with inflammation.1 Radiographic studies may show joint erosions in patients with active rheumatoid arthritis for more than a year, and typical osteophytes and joint-space narrowing in osteoarthritis.1
Radiographs are not necessary for the diagnosis of this patient but may help management, especially if hand surgery is going to be considered. In this case, the radiographs showed joint erosions and unequivocal juxta-auricular osteopenia.