Purpose: Cystinuria is the predominant hereditary factor leading to kidney stone formation in the pediatric population. The aim of this manuscript is to provide an overview of cystinuria in children. Methods: The authors performed a literature review on studies regarding cystinuria in children. A narrative synthesis for analysis of the studies was used. Results: Cystine is a homodimeric amino acid formed by the disulfide bonding of two cysteine molecules. The problem with this autosomal recessive condition arises from a malfunction in the process of reabsorption. Cystine filtered from the renal glomerulus cannot be reabsorbed from the proximal tubules. Therefore, due to its extremely low solubility at normal urine pH, it precipitates and causes stone formation. Recurrent stone formation is the most prominent clinical presentation of cystinuria. The patients usually present with a renal colic episode with concomitant nausea and hematuria. The aim of medical treatment is to maintain the solubility of cystine in urine. The main strategies are to increase urine volume and urinary pH. Potassium citrate or potassium bicarbonate can be used to raise the pH of the urine to 7.5 to increase cystine solubility. If the treatment with alkalinization and higher urine output fails, cystine binding agents such as tiopronin and D-penicillamine can be added to the treatment. Surgical management of pediatric patients with cystine stones is similar to that in the adult population. However, cystine stones can be resistant to ESWL. Retrograde ureteroscopy with semirigid and flexible instruments is a good option for ureteral stones and also for renal stones less than 20 mm in diameter. The golden standard option for high-volume stones larger than 20 mm in diameter is percutaneous nephrolithotomy (PCNL). Conclusions: Cystinuria is the primary hereditary factor contributing to the formation of kidney stones throughout childhood. It is a genetic disorder that typically manifests as recurrent stone formations. The aim of the treatment of genetically caused pediatric stone diseases is to prevent stone formation with medical treatments, remove existing stones through surgical treatments, and mitigate the risk of developing chronic kidney disease in the future.

We aimed to compare recurrence-free survival (RFS) and progression-free survival (PFS) of the patients with pure high-grade (HG) vs mixed-grade (MG) nonmuscle-invasive bladder cancer who received adequate bacillus Calmette-Guérin therapy. We conducted a retrospective cohort analysis using data from an institutional database. The study included patients diagnosed with HG nonmuscle-invasive bladder cancer at the initial transurethral resection specimen between 2010 and 2020. The initial transurethral resection specimens of all patients were reevaluated by a dedicated uropathologist. The percentage of low-grade tumor areas accompanying HG areas was determined for each case. Time-to-event analysis was performed using the Kaplan-Meier method. RFS and PFS rates were compared between groups. Of the 203 patients enrolled in the study, 69 (34%) had MG tumors. Recurrence was observed in 41 out of 134 patients (30.6%) in the HG group and in 19 out of 69 patients (27.5%) in the MG group. The 36-month RFS rates were 69% (CI: 62-77) and 72% (CI: 62-83) for the HG-urothelial carcinoma (UC) and MG-UC groups, respectively. The RFS rates were similar between groups (log-rank, P = .58). Progression was observed in 22 out of 134 patients (16.4%) in the HG group and in 4 out of 69 patients (5.8%) in the MG group. The 36-month PFS rates were 84% (CI: 77-90) and 94% (CI: 89-100) for the HG-UC and MG-UC groups, respectively. The pure HG-UC group had a worse PFS than the MG-UC group (log-rank, P = .042). Multivariate analysis demonstrated that age and tumor grade were significant risk factors for the development of progression. The indication of MG-UC category separately from pure HG carcinomas in the pathology report seems to be an important issue that can guide patient management. In this way, both more accurate risk classification and more accurate patient counseling can be performed. More importantly, the treatment plan can be made more accurately. For more precise conclusions, our results should be supported by prospective studies with larger sample size.