Percutaneous Nephrolithotomy for a 2,8-Dihydroxyadenine Stone in a Horseshoe Kidney

Abstract

Introduction: A 30-year-old healthy man presented for evaluation of a 6-month history of left-sided flank pain and microscopic hematuria. Work-up revealed a large stone of low attenuation within the left renal moiety of a horseshoe kidney. Additionally, dual-energy computed tomography (CT) scanning was performed to characterize the stone preoperatively. Materials and Methods: The patient was taken to the operating room for percutaneous nephrolithotomy. The stone was unable to be reached with the rigid nephroscopy, and flexible nephroscopy was performed. This revealed a large stone floating within the renal pelvis. The stone was noted to be round and red, and have an irregular textured appearance. The stone was first fragmented using the holmium laser and subsequently with ultrasonic lithotripsy where fragments could be reached. Once all fragments were removed, the collecting system was inspected and papillary biopsies were obtained. Results: Gross examination demonstrated a uniform rough surface with the appearance of multiple small red spherules coalesced together. Infrared spectrophotometry was performed on the stone fragments and found them to be composed of 2,8-dihydroxyadenine. Micro-CT scans were performed to further characterize the stones. Conclusion: We present a rare case of a large dihydroxyadenine (DHA) stone requiring percutaneous nephrolithotomy in a patient with a newly diagnosed disease. In general, these stones rarely grow large enough to require surgical intervention. To our knowledge, these are the first documented dual-energy and micro-CT scans of such stones. Further, we provide rarely seen endoscopic and pathologic characterization of the papillary tissue of adenine phosphoribosyltransferase (APRT) deficiency. The authors have nothing to disclose. Runtime of video: 7 mins