Endoscopic and histological images from a brushite SF. (A) Papilla from a brushite SF that was video recorded at the time of stone removal shows depressions (arrows) near the papillary tip and flattening, a phenomenon not seen in CaOx SFs. Like CaOx SFs, the papilla possessed sites of Randall plaque (arrowheads), though lesser in number. In addition, papillae possess sites of a yellowish crystalline deposit at the openings of Bellini ducts (indicated by the asterisk). These ducts were occasionally enlarged and filled with a crystalline material that protruded from the duct (inset, arrow) that might serve as a site for stone attachment. (B) Deposits in the lumens of an individual inner medullary CD (arrow) and in an occasional nearby Henle loop are shown. The crystal deposits greatly expanded the lumen of these tubules, and cell injury to the degree of complete cell necrosis was found. A cuff of interstitial inflammation and fibrosis accompanied sites of intraluminal disposition. (C and D) A cortical sample from a normal human kidney (C) compared with that of a brushite SF (D) that reveals advanced glomerulosclerosis (arrows), moderate tubular atrophy, and interstitial fibrosis — changes not seen in CaOx SFs. Magnification: ×1,400 (B); ×1,000 (C and D). A and B reprinted with permission from Kidney International (92). C and D reprinted with permission from Urological Research (123).