Anti-topoisomerase I (anti-Scl-70) antibody in systemic sclerosis is specifically associated with which clinical subset and complication?
- A Limited cutaneous SSc (lcSSc) and CREST syndrome
- B Overlap syndrome with dermatomyositis
- C Diffuse cutaneous SSc (dcSSc) and pulmonary fibrosis (ILD) ✓
- D Limited cutaneous SSc and isolated pulmonary arterial hypertension
Explanation
Anti-Scl-70 (anti-topoisomerase I) antibodies are a marker for diffuse cutaneous systemic sclerosis (dcSSc) — characterised by rapid, widespread skin involvement beyond elbows/knees and early visceral involvement. The most important complication associated with anti-Scl-70 positivity is pulmonary fibrosis (interstitial lung disease), which is the leading cause of mortality in dcSSc. Anti-centromere antibodies (ACA) are associated with limited cutaneous SSc/CREST syndrome and are specifically linked to pulmonary arterial hypertension. Anti-RNA polymerase III is associated with renal crisis.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
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