Percutaneous and Transureteral Biopsies of Renal Papillae: Safe and Appropriate Procedures for In Vivo Histologic Analysis in Stone Formers

 According to the Randall plaque theory, urinary crystals may attach to focal interstitial deposits of calcium phosphate (CaP), localized in the tip of the renal papillae. The aim of this prospective study was to evaluate the feasibility and safety of papillary biopsy, performed during ureterorenoscopy (URS) or percutaneous nephrolithotomy (PCNL), to obtain, in 0