title: New studies on papillary calculi.
abstract: Five hundred spontaneously passed stones were collected during a three-year period in an outpatient clinic. They were studied under a stereoscopical optical microscope. Complementary analyses were performed with infrared spectroscopy, scanning electron microscopy and EDAX. There were 142 true papillary stones (28.4%). The rest (71.6%) showed different non-papillary patterns. Papillary stones, type 1 (61 calculi), had an apatite plaque of intrapapillary origin of which 14 showed calcified tubules. Type 2 showed other substances, presumably due to crystalluria but not to an interstitial papillary process (28 stones). Type 3 showed no plaques in their concave faces (53 stones). In types 1 and 2 whewellite is a secondary growth, the plaque acting as a trigger for the development of calcium oxalate. The possibility of hidden Randall's plaques is discussed. Stones with papillary patterns are not as rare as hitherto considered and merit microscopical study.
mesh_terms: D004577:Electron Probe Microanalysis; D006801:Humans; D007669:Kidney Calculi / Q000032:analysis / Q000648:ultrastructure*; D007679:Kidney Medulla; D008853:Microscopy; D008855:Microscopy, Electron, Scanning; D013055:Spectrophotometry, Infrared