IgA glomerulonephritis associated with microscopic polyangiitis or Churg-Strauss syndrome.

When renal insufficiency occurs in classical antineutrophil cytoplasm antibody- (ANCA) associated vasculitides, histological examination usually finds pauci-immune focal segmental glomerulonephritis. We report on 2 cases of histologically proven necrotizing vasculitis associated with IgA nephropathy. Concomitant vasculitis and IgA nephropathy has only rarely been reported but this joint occurrence may not be coincidental as its pathophysiology is not known. Among vasculitides, IgA nephropathy has more frequently been associated with Henoch-Schoenlein purpura: one microscopic polyangiitis unusual because the patient simultaneously presented ANCA and microaneurysms, and the other Churg-Strauss syndrome associated with mild renal insufficiency. This uncommon association might represent a possible overlap syndrome between these ANCA-associated vasculitides and IgA nephropathy or simply a new type of glomerulonephritis that must be taken into account in these vasculitides.