A patient with limited cutaneous systemic sclerosis (lcSSc) develops digital ulcers and pitting scars on fingertips. The autoantibody most specifically associated with lcSSc (CREST syndrome) and its clinical significance are:

• A Anti-topoisomerase I (Scl-70); associated with diffuse cutaneous SSc and pulmonary fibrosis
• B Anti-RNA polymerase III; associated with lcSSc and scleroderma renal crisis
• C Anti-centromere antibody (ACA); associated with lcSSc, CREST, and lower risk of pulmonary fibrosis but higher risk of isolated pulmonary arterial hypertension ✓
• D Anti-U3-RNP (anti-fibrillarin); associated with CREST and severe myopathy

Explanation

Anti-centromere antibody (ACA) targeting CENP-B protein is the characteristic autoantibody of limited cutaneous SSc (lcSSc) / CREST syndrome (Calcinosis, Raynaud's, Esophageal dysmotility, Sclerodactyly, Telangiectasia). ACA-positive patients have a lower risk of pulmonary fibrosis compared to diffuse SSc, but carry a specific risk of isolated pulmonary arterial hypertension (PAH) as a late complication. Anti-topoisomerase I (Scl-70) is strongly associated with diffuse cutaneous SSc (dcSSc) with extensive pulmonary fibrosis. Anti-RNA polymerase III (RNA Pol III) is associated with dcSSc and scleroderma renal crisis (hypertensive emergency). Anti-U3-RNP is associated with diffuse SSc particularly in African Americans.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

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