Abstract
The transformation of lupus nephritis from one histologic pattern to another is well described. We report a case of a patient who initially presented with diffuse proliferative glomerulonephritis and was treated with prednisone and mycophenolate mofetil (MMF). She initially responded well to therapy, but later developed high-grade proteinuria while still on MMF and low-dose steroids. A repeat biopsy performed after the increase in proteinuria demonstrated that she had focal proliferative disease but that she had also developed membranous lupus nephritis. Our case is unique in that we report a patient who developed membranous lupus nephritis while receiving MMF.