FAT1-associated membranous nephropathy after hematopoietic stem cell transplantation: a case report and review of the literature.
Ryosuke Saiki, Kan Katayama, Yuto Matsui et al.
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Case in brief
A 55-year-old man developed nephrotic syndrome 52 months post-allogeneic hematopoietic stem cell transplantation for acute lymphoblastic leukemia. Initially presenting with asymptomatic proteinuria, he progressed to significant edema and pleural effusion. Kidney biopsy revealed membranous nephropathy with FAT1 immunofluorescence. Treatment with increased prednisolone and continued tacrolimus led to improvement in proteinuria, serum albumin, and kidney function over five months.
What made this case unusual
The case highlights FAT1-associated membranous nephropathy presenting late after hematopoietic stem cell transplantation, with immunofluorescence showing granular staining despite non-predominant immunoglobulin G4.
Diagnostic / clinical pearl
Clinicians should consider FAT1-associated membranous nephropathy in patients with nephrotic syndrome post-hematopoietic stem cell transplantation, even with non-immunoglobulin G4 staining.
Why it matters
This case underscores the heterogeneous nature of membranous nephropathy and the need for awareness of its variable presentation and treatment responses in post-transplant patients.