Which finding best supports the diagnosis of Henoch-Schonlein Purpura?

Which finding best supports the diagnosis of Henoch-Schonlein Purpura?

• A. Mesangial IgA deposits on kidney biopsy
• B. Low serum IgA levels
• C. Prolonged PT
• D. Thrombocytopenia

Answer: (A)

IgA immune complex deposition in the mesangium is the hallmark finding because Henoch-Schonlein purpura is an IgA-mediated small-vessel vasculitis. The disease often affects the kidneys through deposition of IgA-containing immune complexes in the glomerular mesangium, seen on biopsy as mesangial IgA deposits (often with complement). This directly reflects the underlying pathophysiology and best confirms the diagnosis. By contrast, low serum IgA levels would be inconsistent with IgA vasculitis, a prolonged PT indicates a coagulation issue, and thrombocytopenia would point to a platelet problem rather than vasculitis; in HSP platelets are typically normal.

IgA immune complex deposition in the mesangium is the hallmark finding because Henoch-Schonlein purpura is an IgA-mediated small-vessel vasculitis. The disease often affects the kidneys through deposition of IgA-containing immune complexes in the glomerular mesangium, seen on biopsy as mesangial IgA deposits (often with complement). This directly reflects the underlying pathophysiology and best confirms the diagnosis. By contrast, low serum IgA levels would be inconsistent with IgA vasculitis, a prolonged PT indicates a coagulation issue, and thrombocytopenia would point to a platelet problem rather than vasculitis; in HSP platelets are typically normal.