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Diffuse cutaneous systemic sclerosis — SCE Rheumatology MCQ

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EasyConnective tissue diseasesDiffuse cutaneous systemic sclerosisSCE Rheumatology

A 42-year-old man develops rapidly progressive symmetrical skin thickening extending over the upper arms and trunk. He has new hypertension and an acute rise in serum creatinine. Anti-RNA polymerase III antibodies are positive. What is the most likely underlying diagnosis?

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Correct answer: C — Diffuse cutaneous systemic sclerosis

The diagnosis is diffuse cutaneous systemic sclerosis. Skin thickening extending proximal to the elbows and involving the trunk defines the diffuse cutaneous subset. Anti-RNA polymerase III antibodies are strongly associated with rapidly progressive diffuse skin disease and scleroderma renal crisis. The combination of new hypertension and acute kidney injury indicates probable renal crisis rather than merely an increased future risk. Limited cutaneous systemic sclerosis usually spares the trunk and remains distal to the elbows and knees. Nephrogenic systemic fibrosis is associated with advanced renal failure and gadolinium exposure, not systemic-sclerosis-specific antibodies. Morphea causes localised skin sclerosis without renal crisis, while dermatomyositis is characterised principally by inflammatory myopathy and typical cutaneous eruptions.

Reference: Anti-RNA polymerase III antibodies in systemic sclerosis: prevalence and clinical associations from a systematic review and meta-analysis, 2025. https://pubmed.ncbi.nlm.nih.gov/40676730/