Concomitant monoclonal immunoglobulin deposition disease and crystalglobulin-induced nephropathy with a membranoproliferative pattern of glomerular injury .

Monoclonal immunoglobulin paraproteins can deposit in the kidney in variable forms and eliciting differing patterns of injury. Crystalglobulin-induced nephropathy is a rare form of monoclonal immunoglobulin deposition in the kidney, characterized by glomerular capillary endoluminal crystalline material evident by light and electron microscopy that exhibits immunoglobulin restriction via immunofluorescence studies. We present a case of a patient with acute kidney injury, and a subsequent kidney biopsy notably revealed concurrent monoclonal immunoglobulin deposition disease (MIDD) and crystalglobulin-induced nephropathy secondary to an IgM/κ monoclonal protein that resulted in a membranoproliferative pattern of glomerular injury.