An 8-year-old boy develops palpable purpura over the buttocks and legs, colicky abdominal pain, arthritis of the knees, and microscopic hematuria with proteinuria. Renal biopsy shows mesangial proliferation, and immunofluorescence reveals IgA deposition in the mesangium. What is the most likely diagnosis?

• A Post-streptococcal glomerulonephritis
• B IgA vasculitis (Henoch-Schonlein purpura) nephritis ✓
• C Wegener granulomatosis (granulomatosis with polyangiitis)
• D Minimal change disease

Explanation

The tetrad of palpable purpura, arthralgia, abdominal pain, and renal involvement in a child with mesangial IgA deposits defines IgA vasculitis. It shares the IgA-dominant deposits of IgA nephropathy but is distinguished by systemic small vessel involvement and its occurrence in children. Post-streptococcal GN follows infection with low C3 and subepithelial humps, while ANCA vasculitis is pauci-immune with no IgA deposits.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.