In Henoch-Schönlein Purpura (IgA vasculitis), the distinguishing DIF finding from skin biopsy is:
- A IgA deposits in vessel walls of the upper dermis ✓
- B Linear IgG and C3 at the dermoepidermal junction
- C Granular IgM and C3 at dermal papillae
- D IgG and C3 in intercellular spaces of the epidermis
Correct answer: A. IgA deposits in vessel walls of the upper dermis
Explanation
Henoch-Schönlein Purpura (now termed IgA vasculitis) is a small-vessel vasculitis mediated by IgA1-dominant immune complex deposition. DIF of lesional skin characteristically shows IgA deposits in the walls of small dermal vessels (venules), differentiating it from other small-vessel vasculitides where IgG/IgM predominate. The systemic correlate is IgA nephropathy (mesangial IgA deposits in the kidney). This IgA vascular pattern is the sine qua non of the diagnosis when clinical features are ambiguous.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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