A 6-year-old boy develops palpable purpura over the buttocks and legs, colicky abdominal pain, and arthralgias two weeks after an upper respiratory infection. Urinalysis shows microscopic hematuria. Skin biopsy shows leukocytoclastic vasculitis. Which immunoglobulin is deposited in the vessel walls?
- A IgG
- B IgA ✓
- C IgM
- D IgE
Correct answer: B. IgA
Explanation
Henoch-Schonlein purpura (IgA vasculitis) is a small-vessel leukocytoclastic vasculitis of children that follows mucosal infections. Deposition of IgA-containing immune complexes in affected tissues is its defining feature and gives it the modern nomenclature IgA vasculitis. IgG-dominant deposits would suggest other immune complex small-vessel vasculitides such as cryoglobulinemic or lupus-associated vasculitis.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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