Tubular basement membrane (TBM) deposits are very uncommon in non-lupus membranous nephropathy. We report a series of 5 patients with membranous nephropathy and extensive TBM deposits following allogeneic hematopoietic cell transplant. Patients presented with nephrotic syndrome with (n=3) acute kidney injury, late post-transplant in association with chronic graft-vs-host disease (cGVHD). Kidney biopsies revealed global subepithelial and extensive TBM immune complex deposits, accompanied by acute tubular injury (n=4) and tubulointerstitial inflammation (n=4). Proteomic analysis of glomeruli in 4 cases revealed spectra for PLA2R in 1 and no significant protein spectra for PLA2R, THSD7A, EX1/2, NELL-1, PCDH7, NCAM1, or SEMA3B in the remaining 3. On follow up (mean 42 months), 4 patients had complete and 1 partial remission following prednisone and/or rituximab therapy. We propose that membranous nephropathy with extensive TBM deposits is a distinctive clinicopathologic lesion associated with allogeneic hematopoietic cell transplant. Pathogenesis likely involves cGVHD-driven antibodies against glomerular and TBM components, the identity of which remains to be elucidated.
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