Minimal change disease: A case report of an unusual relationship.

Kidney injury associated with lymphoproliferative disorders is rare, and the exact pathogenetic mechanisms behind it are still poorly understood. Glomerular involvement presenting as a nephrotic syndrome has been reported, usually secondary to membranoproliferative glomerulonephritis. We report a case of a 63-year-old male who presented with bilateral leg swelling due to nephrotic syndrome and acute kidney injury. A kidney biopsy showed minimal change disease with light chain deposition; however, no circulating light chains were present. This prompted a bone marrow biopsy, which showed chronic lymphocytic leukemia (CLL) with deposition of the same kappa monoclonal light chains. Three cycles of rituximab and methylprednisolone resulted in remission of both CLL and nephrotic syndrome, without recurrence during a three-year follow-up.