Dual pathology as a cause of proteinuria in the post-transplant period; report of a case

Proteinuria is common after renal transplantation and affects between 35%-45% of patients during the same year as their transplant. We report a case of dual pathology in the renal allograft as a cause of severe proteinuria. A 38-year-old male presented with end-stage renal disease. He underwent live related renal allograft transplant. His immediate post-transplant period was unremarkable. He developed rise in serum creatinine (2.1 mg/dl) 6 months after transplant and was biopsied. He was diagnosed as a case of acute cellular rejection type Ib with suspicion for antibody mediated rejection. He was treated with methylprednisolone to which he showed a good response with return of serum creatinine to 1.6 mg/dl. Subsequently, he developed a nephrotic range proteinuria 6 months after this episode of rejection. Repeat biopsy was performed. He was diagnosed as a case of immune complex mediated glomerulonephritis (GN) (morphologically consistent with pattern of membranoproliferative glomerulonephritis) with chronic humoral rejection in the form of transplant glomerulopathy (TG). IHC for C4d and immunofluorescence studies were instrumental making the diagnosis. He was treated with steroids and rituximab to which he showed a good response with remission of proteinuria. This case highlights the importance of picking up dual pathology in an allograft biopsy to ensure appropriate therapy. The role of C4d and its correct interpretation is further highlighted, especially with regard to pattern (granular versus linear) and location (glomerular capillaries versus peritubular capillaries).