Once in a Blue Moon: Crescentic Diabetic Kidney Disease

Introduction: Diabetic nephropathy is the leading cause kidney disease worldwide. Crescentic diabetic nephropathy is a rare occurrence and herein we present a case of diabetic kidney disease (DKD) with crescents formation in a kidney transplant recipient. Case Description: A 65-year-old male with type 2 diabetes, hypertension, and atrial fibrillation who received a deceased donor kidney transplant in 2011 presented for routine follow up in clinic. His post-transplant course was unremarkable except for the development of low-grade prostate cancer managed with active surveillance and reduction in immunosuppression. The patient started to have worsening proteinuria up to 4.95 g/d and declining kidney function with creatinine of 1.7 mg/dL. HLA-DSA, PLA2R-Ab, and ANCA all were negative. No monoclonal protein detected by SPEP or UPEP and FLC ratio was normal. Kidney biopsy was pursued which showed characteristic diabetic changes. Interestingly, three glomeruli showed cellular crescents. There was no deposits or linear IgG staining on immunofluorescence. Electron microscopy showed severely thickened glomerular basement membrane without any deposits or fibrils. The patient was started on ARBs and proteinuria started to improve. Discussion: While DKD is the most common cause of ESKD globally, the formation of crescents within the context of DKD is relatively rare. Crescents formation in the setting of DKD is mainly seen in association with other glomerular pathologies commonly known to present with crescentic glomerulonephritis. The presence of crescents in the setting of DKD is associated with a worse prognosis and points toward a more aggressive diabetic nephropathy. The absence of deposits in our patient with negative serological and monoclonal work up in addition to the absence of linear IgG staining by IF, rules out other pathology responsible for crescents formation.