American Board of Internal Medicine (ABIM) Certification Practice Exam

Which condition's radiographic findings include marginal erosions?

1. Systemic sclerosis

2. Rheumatoid arthritis

3. Osteoarthritis

4. Psoriatic arthritis

The correct answer is: Rheumatoid arthritis

Marginal erosions are a key radiographic finding associated with rheumatoid arthritis. This condition is characterized by symmetrical polyarthritis that primarily affects the small joints of the hands and feet, leading to joint destruction and deformities over time. On X-ray, these erosions typically appear at the joint margins, reflecting the inflammatory process that targets both the synovial tissue and the adjacent bone. Rheumatoid arthritis is an autoimmune disorder, and the erosions represent the result of chronic inflammatory activity that causes damage to the bone around a joint. This is a distinguishing feature not typically found in osteoarthritis, which is more related to wear and tear without significant erosive change, or in systemic sclerosis and psoriatic arthritis, which have different patterns of involvement. In psoriatic arthritis, for instance, you might see a combination of erosive disease and unique features such as "pencil-in-cup" deformities. Understanding these distinctions helps in diagnosing and managing these conditions effectively, emphasizing the importance of recognizing marginal erosions as a hallmark of rheumatoid arthritis on radiographs.