Recurrent Nephrolithiasis in Congenital Cystinuria With a Complete Duplex Collecting System: A Case Report.

Cystinuria is a rare autosomal recessive genetic disorder that affects the reabsorption of cystine in the renal tubules. Although cysteine lithiasis is a rare form of nephrolithiasis, it typically presents early in life and is associated with a highly recurrent course and frequent need for repeated surgical interventions. The presence of a duplicated collecting system adds complexity, as it can hinder drainage and make endoscopic access more difficult. We report the case of a 16-year-old male patient with congenital cystinuria and a complete bilateral duplex collecting system. He presented with recurring colicky pain in his right flank. CT imaging showed lower calyceal cystine stones and bilateral nephrocalcinosis. The initial treatment with extracorporeal shock wave lithotripsy (ESWL) was unsuccessful, leading to staged endoscopic intervention. During ureteroscopy (URS), the tight structure of the ureter and the unfavorable position of the stones made access difficult. This resulted in insufficient fragmentation and the eventual migration of the stone into a deeper calyx that was hard to reach. The procedure was stopped to prevent injury to the ureter. After the surgery, we recommended aggressive hydration and starting an angiotensin-converting enzyme (ACE) inhibitor, with percutaneous nephrolithotomy (PCNL) considered for the future based on how the stones developed. Cystinuria often requires repeated surgeries, and having a duplex collecting system makes these procedures more challenging and likely to fail. This case illustrates the limitations of URS in complicated anatomical situations. It also emphasizes the need for personalized treatment plans, which may include switching from surgical methods to conservative management when the anatomy makes safe stone removal difficult. Recurrent cystinuria-related kidney stones in a duplex collecting system pose special challenges for diagnosis and treatment. A multidisciplinary approach is crucial to improve outcomes, lower the risks of procedures, and maintain long-term kidney health.