A rare case of crystalglobulinemia

Crystalglobulinemia is an extremely rare complication of monoclonal gammopathy. We report a 49-year-old female who presented with acute kidney injury, microhematuria, and non-nephrotic range proteinuria. Eight weeks prior to presentation, she developed a lower urinary tract infection and acute kidney injury, but her creatinine failed to resolve after resolution of her symptoms with antibiotics. Kidney biopsy revealed a membranoproliferative pattern of injury, and numerous crystals were noted in the glomerular capillaries on electron microscopy. On immunofluorescence, positive staining for immunoglobulin G and kappa was demonstrated in the capillary lumen along the capillary walls. Based on the biopsy, a diagnosis of crystalglobulinemia was made. On serum protein electrophoresis, there was presence of a monoclonal band, which was too small to quantify. Urine immunofixation was negative. Patient was treated with cyclophosphamide, bortezomib, and dexamethasone regime and made a remarkable renal recovery