Posttransplant de novo membranous nephropathy in childhood.

Posttransplant proteinuria is a recognized, but relatively uncommon, presentation of renal transplant dysfunction. Significant proteinuria occurs in around 10-15% of renal transplant recipients. We present a case of de novo posttransplant membranous nephropathy in childhood complicating renal transplantation for severe congenital obstructive uropathy and review the pathology, pathogenesis, and clinical implications of this condition. In the majority of cases, the cause of posttransplant proteinuria is either related to chronic allograft nephropathy or recurrence of the glomerulonephritis for which transplantation was indicated. In a minority, however, de novo posttransplant membranous nephropathy (DNPMN) is identified on biopsy. The histopathological findings in some cases may either be similar to those of classical membranous nephropathy, or may be more subtle, showing focal segmental variation in severity, often in conjuction with the features of chronic allograft nephropathy. The use of ancillary techniques including immunohistochemistry and electron microscopy may be required to confirm the diagnosis. The presence of posttransplant de novo membranous nephropathy may be associated with an increased risk of graft loss.