Crystalglobulinemia causing cutaneous vasculopathy and acute nephropathy in a kidney transplant patient

We present a rare case of crystalglobulinemia causing cutaneous vasculopathy and acute nephropathy in a 66-year-old female kidney transplant recipient. The patient presented with acute kidney injury (AKI), volume overload, anuria, retiform purpura, and blue-black necrosis of her toes. She received a living kidney transplant 7 months earlier with baseline creatinine of 0.6 mg/dl. Transplant kidney biopsy showed massive pseudo-thrombi filling glomerular capillary lumina. Electron microscopy of thrombi revealed an ultrastructural crystalline pattern of linear and curvilinear bundles with ladder-like periodicity typical of crystalglobulin-induced nephropathy. Similar crystalline pseudo-thrombi were detected ultrastructurally in a skin biopsy specimen, indicating systemic involvement. She required several sessions of hemodialysis. Plasmapheresis was initiated to decrease the number of circulating crystalglobulins. In order to treat the underlying paraproteinemia, the patient was started on bortezomib and dexamethasone. After treatment with five cycles of bortezomib, the patient's free kappa to lambda ratio improved to 2.35 from 5.52. Acute kidney injury (AKI) and the cutaneous vasculopathy gradually improved with treatment. This is an extremely rare occurrence of crystalglobulin in a living kidney transplant recipient.