Different effects of rituximab on a native kidney and a post-transplant kidney with recurrence of focal segmental glomerulosclerosis.

We present the case of a 29-year-old woman with focal segmental glomerulosclerosis (FSGS) who was treated with rituximab administration under different conditions for refractory nephrotic syndrome and posttransplant FSGS recurrence. At the age of 13 years, she developed FSGS, which followed a refractory clinical course, and eventually necessitated her to undergo plasmapheresis and receive rituximab at the age of 25 years. However, both therapies were ineffective, and she subsequently had progressive renal failure, for which dialysis was initiated at the age of 26 years. At the age of 28 years, she received a renal transplant from a living donor. However, nearly 1 year after the transplantation, nephrotic-range proteinuria was observed and FSGS recurrence was confirmed via biopsy of the transplanted kidney. Plasmapheresis resulted in complete remission, which was maintained by rituximab administration, and the patient followed a favorable course. To date, there have been no reports on the effect of rituximab on both the native kidney and post-transplant FSGS recurrence in the same patient. Interestingly, this case showed different responses to rituximab administration.