Which serological marker is most specific for diffuse cutaneous systemic sclerosis (dcSSc) with highest risk of renal crisis?

• A Anti-centromere antibody (ACA)
• B Anti-Scl-70 (anti-topoisomerase I) antibody
• C Anti-U1 RNP antibody
• D Anti-RNA polymerase III antibody ✓

Explanation

Anti-RNA polymerase III antibodies are highly associated with diffuse cutaneous SSc and specifically with scleroderma renal crisis (SRC), a severe acute-onset hypertension with microangiopathic haemolytic anaemia and renal failure. Anti-centromere antibodies are characteristic of limited cutaneous SSc and correlate with PAH risk, not renal crisis. Anti-Scl-70 is associated with dcSSc and ILD, not predominantly with renal crisis. Anti-U1 RNP is the hallmark of mixed connective tissue disease.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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