Recurrent Light Chain Proximal Tubulopathy in a Kidney Allograft.
We describe a rare case of light chain proximal tubulopathy developing in a kidney transplant 12 months following transplantation. The patient was known to have a monoclonal gammopathy of undetermined significance (MGUS) for more than 15 years. A kidney biopsy done to determine the cause of decline in kidney transplant function showed light chain proximal tubulopathy characterized by numerous eosinophilic and fuchsinophilic granules in proximal tubular epithelial cells, which stained for κ light chains on pronase-based immunofluorescence studies. Electron microscopy confirmed the diagnosis and showed numerous amorphous and geometrically shaped inclusions in proximal tubular epithelial cells. Evaluation of free light chains revealed markedly elevated κ light chains and bone marrow biopsy showed 5% to 10% κ light chain-restricted plasma cells. Retrospective evaluation of the native kidney biopsy performed 15 years earlier also showed numerous fuchsinophilic granules in proximal tubules that stained brightly for κ light chains on pronase-based immunofluorescence studies. The patient was treated with a regimen of bortezomib and dexamethasone with good partial hematologic response and improvement of kidney function. To summarize, we describe a case of recurrent light chain proximal tubulopathy in the transplant, which is an unusual but important cause of decreased kidney function in the setting of a monoclonal gammopathy.
Division of Nephrology and Hypertension, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN.
Andrea
A
Angioi
The William J von Liebig Center for Transplantation and Clinical Regeneration, Mayo Clinic, Rochester, MN.
Hatem
H
Amer
Division of Nephrology and Hypertension, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN.
Fernando C
FC
Fervenza
Division of Anatomic Pathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN. Electronic address: sethi.sanjeev@mayo.edu.
Sanjeev
S
Sethi
D000368:Aged; D005260:Female; D006801:Humans; D007674:Kidney Diseases / Q000276:immunology*; D016030:Kidney Transplantation; D007687:Kidney Tubules, Proximal; D010265:Paraproteinemias / Q000150:complications*; D011183:Postoperative Complications / Q000276:immunology*; D012008:Recurrence
Allograft; kidney biopsy; light chain proximal tubulopathy (LCPT); monoclonal gammopathy; monoclonal gammopathy of undetermined significance (MGUS); multiple myeloma; recurrent LCPT; renal transplantation