Congenital bilateral renal arteriovenous malformation: an unrecognized cause of renal failure

Congenital renal arteriovenous malformations (AVM) are very rare abnormal communications between arteries and veins. These lesions are almost always unilateral, predominantly in the right kidney, and usually asymptomatic until adulthood. We present a unique case of bilateral renal AVM in a 10-year-old white boy who developed renal failure requiring renal transplantation. Microscopic sections of an atrophic right and a slightly larger left kidney with tortuous and dilated hilar vessels showed elaborate derangement of arteries and veins insinuating between lobules. Glomeruli were diffusely enlarged with increased number of capillary loops. Glomerular basement membrane reduplication and fibrinoid necrosis was focally noted. Electron microscopy demonstrated absence of electron-dense deposits or mesangial interposition excluding membranoproliferative glomerulonephritis. We believe that the glomerular lesions are secondary to congenital renal arteriovenous malformation. To our knowledge, bilateral arteriovenous malformation in infancy is not previously described.