Kaygisiz O, et al. - Researchers probed the relationship between renal stone composition and percutaneous nephrolithotomy outcomes in pediatric patients and defined the characterization of the stone composition. They retrieved the data of children who underwent percutaneous nephrolithotomy between 1991 and 2012 from the multicenter database of the Turkish Pediatric Urology Society. For the outcomes of pediatric percutaneous nephrolithotomy, the stone composition was not a predictor. Nonetheless, more challenging cases that needed multiple tracts were the cystine and infection stones, which were larger and filled multiple calyxes due to the nature of stone forming.