Nephrotic syndrome: an under‐recognised immune‐mediated complication of non‐myeloablative allogeneic haematopoietic cell transplantation

Summary Nephrotic syndrome (NS) is an extremely rare complication of myeloablative allogeneic haematopoietic cell transplantation (HCT) that usually occurs in association with chronic graft‐versus‐host disease (C‐GVHD). We observed an unexpectedly high incidence of NS in a cohort of 163 consecutive patients undergoing non‐myeloablative HCT from a related human leucocyte antigen‐compatible donor. Seven patients developed NS at a median 318 d post‐transplant (range 119–1203 d; cumulative incidence 6·1%). The median age at onset of NS was 46 years (range 33–59 years); three of the seven patients had no evidence of C‐GVHD while four had accompanying limited C‐GVHD. At diagnosis, median proteinuria was 16·5 g/24 h (range 3–24 g/24 h). Renal biopsy was performed in four cases and revealed membranous nephropathy. NS was not always associated with other symptoms of C‐GVHD, and in contrast to previous reports, usually did not improve with the re‐initiation of aggressive immunosuppression, resulting in progressive renal failure necessitating dialysis in three of seven cases. Membranous nephropathy resulting in NS is a previously unrecognised and clinically significant complication of non‐myeloablative HCT.