In scleroderma, which antibody is associated with the diffuse form and worse prognosis?

• A. ANA
• B. Anticentromere Ab
• C. Anti-SCL-70 Ab
• D. RF

Answer: (C)

Anti-Scl-70 antibodies (anti-topoisomerase I) are linked to the diffuse form of systemic sclerosis and to more severe disease with higher risk of organ fibrosis, especially interstitial lung disease, which explains the worse prognosis. In contrast, anticentromere antibodies are more commonly seen with the limited cutaneous form (CREST) and tend to have a better overall prognosis. ANA is a general, non-specific marker that can be positive in many autoimmune conditions, not tied to the specific disease form or prognosis. RF is typically associated with rheumatoid arthritis and is not a defining marker for systemic sclerosis.