American Board of Internal Medicine (ABIM) Certification Practice Exam

Anti-Scl-70 antibodies are primarily associated with which type of scleroderma?

1. Limited scleroderma

2. Crest syndrome

3. Diffuse scleroderma

4. Rheumatoid arthritis

The correct answer is: Diffuse scleroderma

Anti-Scl-70 antibodies, also known as anti-topoisomerase I antibodies, are primarily associated with diffuse scleroderma. This autoimmune condition is characterized by widespread skin involvement and a more aggressive course compared to limited scleroderma. In diffuse scleroderma, patients often experience rapid progression of skin thickening and are at a greater risk for internal organ involvement, particularly the lungs and kidneys. The presence of anti-Scl-70 antibodies is indicative of this broader systemic involvement, which is a hallmark of diffuse scleroderma. In contrast, limited scleroderma, including CREST syndrome, tends to have milder symptoms and a more indolent course, often associated with different autoantibodies, such as anticentromere antibodies. Understanding the specific association of anti-Scl-70 antibodies with diffuse scleroderma is key for diagnosing and managing this condition and highlights the importance of autoantibody testing in the evaluation of patients suspected of having scleroderma.