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stone interface
32nd Annual EAU Congress, 24-28 March 2017, London, United Kingdom
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Calcium oxalate stone formation: Microstructural evaluation of Randall plaque and the plaque/stone interface Eur Urol Suppl 2017; 16(3);e12
Wendt-Nordahl G.1, Sethmann I.2, Enzmann F.3, Simon L.3, Knoll T.1, Klebe H.-J.2 1
Klinikum Sindelfingen-Böblingen, Dept. of Urology, Sindelfingen, Germany, 2Technical University Darmstadt, Institut für Angewandte Geowissenschaften, Darmstadt, Germany, 3University Mainz, Institut für Geowissenschaften, Mainz, Germany INTRODUCTION & OBJECTIVES: One theory of idiopathic calcium oxalate (CaOx) stone formation involves the formation of calcium phosphate (CaP) plaques in the interstitium of the renal papilla (Randall plaque, RP) and subsequent deposition of CaOx at the RP–urine interface. Aim of the study was to further investigate RP and its interface with the stone for clues on the mechanisms of mineral precipitation. MATERIAL & METHODS: Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), micro-X-ray-computed tomography and X-ray diffractometry were used to investigate four kidney stones harvested during percutaneous stone treatment in CaOx stone forming patients. RESULTS: The kidney stones were predominantly composed of calcium oxalate monohydrate (COM), whereas a small section of the surface area consisted of CaP corresponding to RP as the attachment site of the stone to the renal papilla.In the CaP plaque, mineralized tubules with diameters between 10 and 40µm were found. Whereas the complete outer surfaces of the tubes were mineralized, the lumina of most tubules were void of CaP particles. Neighboring the tubules, spherical CaP deposits were encountered in fibrillar tissue. At the plaque-stone interface COM crystals were found ranging from a stacked platelet structure to a porous dendritic structure in direct vicinity of the peripheral layer of RP. Furthermore, the initial layers of COM crystals at the interface were often covered with coatings or crusts of CaP. CONCLUSIONS: Morphologies of RP particles suggest CaP precipitation from the interstitial fluid, initially as an amorphous phase that may crystallize later on. Diffusion of calcium and phosphate ions through the boundary of RP into caliceal urine seems possible. There, these additional ions may contribute to initial CaOx precipitation at the plaque–stone interface and cause subsequent CaP coating of the first CaOx crystals.
Eur Urol Suppl 2017; 16(3);e12 Powered by TCPDF (www.tcpdf.org)
8
Calcium oxalate stone formation: Microstructural evaluation of Randall plaque and the plaque/stone interface Eur Urol Suppl 2017; 16(3);e12
Wendt-Nordahl G.1, Sethmann I.2, Enzmann F.3, Simon L.3, Knoll T.1, Klebe H.-J.2 1
Klinikum Sindelfingen-Böblingen, Dept. of Urology, Sindelfingen, Germany, 2Technical University Darmstadt, Institut für Angewandte Geowissenschaften, Darmstadt, Germany, 3University Mainz, Institut für Geowissenschaften, Mainz, Germany INTRODUCTION & OBJECTIVES: One theory of idiopathic calcium oxalate (CaOx) stone formation involves the formation of calcium phosphate (CaP) plaques in the interstitium of the renal papilla (Randall plaque, RP) and subsequent deposition of CaOx at the RP–urine interface. Aim of the study was to further investigate RP and its interface with the stone for clues on the mechanisms of mineral precipitation. MATERIAL & METHODS: Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), micro-X-ray-computed tomography and X-ray diffractometry were used to investigate four kidney stones harvested during percutaneous stone treatment in CaOx stone forming patients. RESULTS: The kidney stones were predominantly composed of calcium oxalate monohydrate (COM), whereas a small section of the surface area consisted of CaP corresponding to RP as the attachment site of the stone to the renal papilla.In the CaP plaque, mineralized tubules with diameters between 10 and 40µm were found. Whereas the complete outer surfaces of the tubes were mineralized, the lumina of most tubules were void of CaP particles. Neighboring the tubules, spherical CaP deposits were encountered in fibrillar tissue. At the plaque-stone interface COM crystals were found ranging from a stacked platelet structure to a porous dendritic structure in direct vicinity of the peripheral layer of RP. Furthermore, the initial layers of COM crystals at the interface were often covered with coatings or crusts of CaP. CONCLUSIONS: Morphologies of RP particles suggest CaP precipitation from the interstitial fluid, initially as an amorphous phase that may crystallize later on. Diffusion of calcium and phosphate ions through the boundary of RP into caliceal urine seems possible. There, these additional ions may contribute to initial CaOx precipitation at the plaque–stone interface and cause subsequent CaP coating of the first CaOx crystals.
Eur Urol Suppl 2017; 16(3);e12 Powered by TCPDF (www.tcpdf.org)