title: Endoscopic and Pathologic Characterization of Papillary Architecture in Struvite Stone Formers.
abstract: OBJECTIVE
  To describe the endoscopic characteristics of renal papillae in struvite stone formers (SFs).
  
  
  METHODS
  From 2009 to 2014, patients undergoing percutaneous nephrolithotomy were prospectively enrolled in our study. Endoscopic analysis and biopsy of papillae were performed to demonstrate the presence and percentage surface area (SA) of Randall's plaque or ductal plug. Comparison with idiopathic calcium oxalate (CaOx) SF and non-SF controls was performed.
  
  
  RESULTS
  We identified 29 struvite SFs to compare with 90 idiopathic CaOx SFs and 17 controls. On endoscopic mapping, 28 struvite SFs (97%) demonstrated Randall's plaque and 9 (31%) had plugging. The average mean SA of Randall's plaque in struvite SF (1.5 ± 1.4%) was less than CaOx SFs (3.7 ± 4.3%, P  =  .0018) and similar to controls (1.7 ± 2.7%, P  =  .76). Average mean plug SA was similar between struvite SFs, CaOx SFs, and controls. On metabolic assessment, 83% of struvite SFs had at least one urine abnormality, with urinary uric acid and oxalate levels significantly higher among struvite SFs compared to controls (P  =  .002). Despite lack of active urinary tract infection, interstitial inflammation was more prevalent in struvite SFs compared to CaOx SFs (43.5% vs 7.3%, P  =  .0001).
  
  
  CONCLUSIONS
  Our findings suggest a limited role for Randall's plaque in struvite stone formation. Struvite SFs have less plaque formation than CaOx SFs, but demonstrate evidence of severe parenchymal inflammation compared to other SFs. The role of this prominent interstitial inflammation requires further study.
authors.affiliation: Department of Urology, Mayo Clinic School of Medicine, Rochester, MN.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Jaeger
authors.affiliation: Division of Hypertension and Nephrology, Mayo Clinic School of Medicine, Rochester, MN.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Rule
authors.affiliation: Division of Health Science Research, Mayo Clinic School of Medicine, Rochester, MN.
authors.forename: Ramila A
authors.initials: RA
authors.lastname: Mehta
authors.affiliation: Division of Health Science Research, Mayo Clinic School of Medicine, Rochester, MN.
authors.forename: Lisa E
authors.initials: LE
authors.lastname: Vaughan
authors.affiliation: Department of Radiology, Mayo Clinic School of Medicine, Rochester, MN.
authors.forename: Terri J
authors.initials: TJ
authors.lastname: Vrtiska
authors.affiliation: Biomedical Imaging Center, Mayo Clinic School of Medicine, Rochester, MN.
authors.forename: David R
authors.initials: DR
authors.lastname: Holmes
authors.affiliation: Division of Health Science Research, Mayo Clinic School of Medicine, Rochester, MN.
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: McCollough
authors.affiliation: Department of Urology, Mayo Clinic School of Medicine, Rochester, MN.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Ziegelmann
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic School of Medicine, Rochester, MN.
authors.forename: Loren P
authors.initials: LP
authors.lastname: Herrera Hernandez
authors.affiliation: Division of Hypertension and Nephrology, Mayo Clinic School of Medicine, Rochester, MN.
authors.forename: John C
authors.initials: JC
authors.lastname: Lieske
authors.affiliation: Department of Urology, Mayo Clinic School of Medicine, Rochester, MN. Electronic address: krambeck.amy@mayo.edu.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Krambeck
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000737:chemistry / Q000473:pathology*; D017616:Magnesium Compounds / Q000032:analysis; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000032:analysis; D011446:Prospective Studies; D012307:Risk Factors; D000069877:Struvite; D018666:Ureteroscopy
chemical_list: D017616:Magnesium Compounds; D010710:Phosphates; D000069877:Struvite