Crystalline Nephropathy in Kidney Allografts: Lessons from a Three-case Experience

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BSTRACT

Crystal-induced nephropathy is an under-recognized cause of graft dysfunction post renal transplantation. We present three cases of crystal deposition disease in kidney allografts with distinct pathophysiologic mechanisms. Three renal transplant recipients presenting with persistent or progressive graft dysfunction underwent biopsy. Biopsy findings revealed intratubular crystal deposition in all cases. Biochemical, genetic, and drug history evaluations were undertaken. Case 1 was a 14-year-old boy with recurrence of primary hyperoxaluria type 1, confirmed by AGXT gene mutation. Case 2, a 48-year-old man, developed crystal nephropathy following valganciclovir use for CMV infection, suggesting a possible drug-induced etiology. Case 3, a 55-year-old gentleman with diabetic kidney disease, developed oxalate crystal deposition 24 months post-transplant with no identifiable metabolic or genetic cause. All patients had normal 24-hour urine metabolic profiles. Crystals were birefringent and needle-shaped, with varying degrees of tubular injury and interstitial fibrosis. Crystal deposition disease is an important differential in graft dysfunction. Pre-transplant screening for oxalate disorders, judicious drug use, and early biopsy is essential to prevent irreversible damage.