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Difficulty: MediumRheumatology and Immunology

Match each clinical presentation to the highly specific autoantibody most closely associated with the underlying diagnosis.

  • A patient with new-onset skin thickening proximal to the elbows, accompanied by bibasilar pulmonary crackles.Anti-topoisomerase I (anti-Scl-70) antibodies
  • A patient presenting with puffy hands, severe Raynaud phenomenon, and clinical features overlapping lupus and myositis.Anti-U1 ribonucleoprotein (RNP) antibodies
  • A patient treated for a cardiac arrhythmia who develops polyarthritis and pleuritis, without evident renal or neurologic disease.Anti-histone antibodies
  • A patient with chronic otitis media, recurrent epistaxis, nasal septal perforation, and active glomerulonephritis.Anti-proteinase 3 (c-ANCA) antibodies

Answer

Diffuse systemic sclerosis pairs with anti-topoisomerase I; mixed connective tissue disease pairs with anti-U1 RNP; drug-induced lupus pairs with anti-histone; and granulomatosis with polyangiitis pairs with anti-proteinase 3.
Each clinical scenario contains pathognomonic features that point to a distinct rheumatologic or vasculitic diagnosis. Matching them correctly requires knowing the specific autoantibody profile that confirms each disease.

Step-by-Step Solution

1
Analyze the first clinical presentation regarding proximal skin thickening and lung crackles.
Identified as diffuse systemic sclerosis.
This establishes the need to pair it with anti-topoisomerase I (anti-Scl-70), its specific serologic marker.
2
Evaluate the second presentation involving puffy hands and overlapping connective tissue features.
Recognized as mixed connective tissue disease (MCTD).
MCTD is defined serologically by the presence of anti-U1 RNP antibodies.
3
Assess the third patient taking an anti-arrhythmic medication who developed mild lupus-like symptoms.
Diagnosed as drug-induced lupus.
Drug-induced lupus is classically associated with anti-histone antibodies, unlike systemic lupus erythematosus which features anti-dsDNA.
4
Review the final vignette detailing upper airway destruction and renal disease.
Identified as granulomatosis with polyangiitis (GPA).
GPA is a small-vessel vasculitis strongly linked to c-ANCA (anti-proteinase 3) antibodies.

Key Concept

Serologic Autoantibodies in Rheumatologic Diseases
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Topics

Rheumatology and Immunology

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