Metamorphism: Crescentic Transformation with Anti‐GBM (Glomerular Basement Membrane) Antibodies Arising from Idiopathic Membranous Glomerulopathy

Case Presentation:

Rapidly progressive glomerulonephritis (RPGN) is a well‐known cause of acute renal failure. However, its abrupt presentation with anti‐GBM antibodies in the setting of membranous nephropathy is quite uncommon, A 73‐year‐old man presented with fatigue and pedal edema. Initial renal function was normal but proteinuria was in the nephrotic range without hematuria. Renal biopsy confirmed membranous glomerulopathy with crescentic glomerulonephritis. An autoimmune workup was negative, establishing idiopathic glomerulopathy. One week later he presented with new hematuria and renal failure. Magnetic resonance venography ruled out renal vein thrombosis. A cystoscopy showed bilateral efflux of hematuria. The patient's kidney function continued to worsen, and he was put on hemodialysis. When anti‐GBM antibodies returned strongly positive, steroids, plasmapheresis, and cyclophosphamide were started. He was tapered off prednisone and taken off hemodialysis in 1 month, after renal function improved. Plasmapheresis was continued until anti‐GBM antibodies were undetectable on repeated occasions. His kidney function has improved and stabilized on 2‐year follow‐up.

Discussion:

This case illustrates an uncommon association of nephrotic syndrome with nephritic features. To date, there have been fewer than 20 cases described in the literature. With pathophysiology incompletely understood, it is unclear which entity to treat. In addition, there is no clear treatment regimen for anti‐GBM disease. Furthermore, severity appears linked to the anti‐GBM antibody titers. It is unknown whether anti‐GBM antibody may also be a prognostic indicator. Treatment should target removal of antibody and plasmapheresis continued till serial anti‐GBM antibody levels are undetectable.

Conclusions:

A successful outcome in treating the nephritic transformation of a nephrotic syndrome may further define a new prognostic marker as well as consolidate treatment strategy in membranous nephropathy complicated by anti‐GBM disease.

Author Disclosure:

R. Prakash, none.