Crescentic glomerulonephritis developing in the course of idiopathic membranoproliferative glomerulonephritis.

Membranoproliferative glomerulonephritis (MPGN) is a rare cause of the nephrotic syndrome in adults and children. Though small focal crescents may be seen in up to 10% of cases of MPGN, the presence of more than 50% crescents (crescentic MPGN) is rare. Very few cases of crescentic transformation of MPGN, documented by subsequent renal biopsies, have been described in the literature. A young female patient underwent kidney biopsy for the nephrotic-nephritic syndrome and was diagnosed as idiopathic MPGN. She was administered immunosuppressive therapy (steroids and cyclophosphamide), with which her renal functions stabilized. Six months later, she presented with features suggestive of rapidly progressive renal failure and underwent a second renal biopsy. The second biopsy showed crescentic glomerulonephritis with immune complex deposition, suggestive of MPGN. A final diagnosis of crescentic transformation of MPGN was made. Crescentic transformation of MPGN is a rare occurrence, but needs to be considered in a patient diagnosed as MPGN and presenting with rapidly progressive renal failure. The cause of such transformation remains to be elucidated.