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Kwenda EP, Hernandez AD, Di Valerio E, Canales BK. Renal papillary tip biopsy in stone formers: a review of clinical safety and insights. Urolithiasis 2024; 52:93. [PMID: 38888601 DOI: 10.1007/s00240-024-01596-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Accepted: 06/10/2024] [Indexed: 06/20/2024]
Abstract
Alexander Randall first published renal papillary tip findings from stone formers in 1937, paving the way for endoscopic assessment to study stone pathogenesis. We performed a literature search to evaluate the safety of papillary tip biopsy and clinical insights gained from modern renal papillary investigations. A search on the topic of renal papillary biopsy provided an overview of Randall's plaques (RP), classification systems for renal papillary grading, and a summary of procedure type, complications, and outcomes. Within 26 identified manuscripts, 660 individuals underwent papillary tip biopsy percutaneously (n = 562), endoscopically (n = 37), or unspecified (n = 23). Post-operative hemoglobin changes were similar to controls. One individual (0.2%) reported fever > 38°, and long-term mean serum creatinine post-biopsy (n = 32) was unchanged. Biopsies during ureteroscopy or PCNL added ~20-30 min of procedure time. Compared to controls, papillary plaque-containing tissue had upregulation in pro-inflammatory genes, immune cells, and cellular apoptosis. Urinary calcium and papillary plaque coverage were found to differ between RP and non-RP stone formers, suggesting differing underlying pathophysiology for these groups. Two renal papillary scoring systems have been externally validated and are used to classify stone formers. Overall, this review shows that renal papillary biopsies have a low complication profile with high potential for further research. Systematic adaption of a papillary grading scale, newer tissue analysis techniques, and the development of animal models of Randall's plaque may allow further exploration of plaque pathogenesis and identify targets for prevention therapies in patients with nephrolithiasis.
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Affiliation(s)
- Elizabeth P Kwenda
- Department of Urology, University of Florida, 1600 SW Archer Road, P.O. Box 100247, Gainesville, FL, 32610-0247, USA.
| | | | | | - Benjamin K Canales
- Department of Urology, University of Florida, 1600 SW Archer Road, P.O. Box 100247, Gainesville, FL, 32610-0247, USA
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Mavridis C, Bouchalakis A, Tsagkaraki V, Somani BK, Mamoulakis C, Tokas T. Recurrent Urinary Stone Formers: Imaging Assessment and Endoscopic Treatment Strategies: A Systematic Search and Review. J Clin Med 2024; 13:3461. [PMID: 38929988 PMCID: PMC11204450 DOI: 10.3390/jcm13123461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Revised: 06/05/2024] [Accepted: 06/12/2024] [Indexed: 06/28/2024] Open
Abstract
Background/Objectives: Nephrolithiasis is a heterogeneous disease with a high prevalence and recurrence rate. Although there has been much progress regarding the surgical treatment of stones, a standardized follow-up, especially in recurrent stone formers (SFs), has yet to be decided. This fact leads to the overuse of computed tomography (CT) scans and many reoperations in patients, thus increasing their morbidity and the financial burden on the health systems. This review systematically searched the literature for original articles regarding imaging strategies and endoscopic treatment for patients with recurrent urolithiasis, aiming to identify optimal strategies to deal with these patients. Methods: We systematically searched the Medline database (accessed on 1 April 2024) for articles regarding imaging modalities and endoscopic treatment for patients with recurrent urinary tract lithiasis. Results: No specific follow-up or endoscopic treatment strategy exists for patients with recurrent urolithiasis. CT scan was the imaging modality most used in the studies, followed by X-ray, ultrasonography, and digital tomosynthesis. A transparent algorithm could not be identified. Percutaneous nephrolithotomy (PCNL), retrograde intrarenal surgery (RIRS), and ureteroscopy (URS) were used in the studies for endoscopic treatment. PCNL showed the best stone-free (SFr) rate and lowest hazard ratio (HR) for reoperation. RIRS showed superiority over extracorporeal shockwave lithotripsy for recurrent SFs, but fragments over 4 mm increased the recurrent rate. URS has an increased HR for reoperation for bilateral stones. Conclusions: The heterogeneity of urolithiasis leaves urologists without a standardized plan for recurrent SFs. Thus, each patient's follow-up should be planned individually and holistically. Pre-stenting is not to be avoided, especially in high-risk patients, and SFr status needs to be the aim. Finally, CT scans should not be generally overused but should be part of a patient's treatment plan. Prospective studies are required to define SFr status, the size of significant residual fragments, and the modalities of intervention and follow-up.
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Affiliation(s)
- Charalampos Mavridis
- Department of Urology, School of Medicine, University General Hospital of Heraklion, 71110 Heraklion, Greece
| | - Athanasios Bouchalakis
- Department of Urology, School of Medicine, University General Hospital of Heraklion, 71110 Heraklion, Greece
| | | | - Bhaskar Kumar Somani
- Department of Urology, University Hospitals Southampton, NHS Trust, Southampton SO16 6YD, UK
| | - Charalampos Mamoulakis
- Department of Urology, School of Medicine, University General Hospital of Heraklion, 71110 Heraklion, Greece
| | - Theodoros Tokas
- Department of Urology, School of Medicine, University General Hospital of Heraklion, 71110 Heraklion, Greece
- Training and Research in Urological Surgery and Technology (T.R.U.S.T.)-Group, 6060 Hall in Tirol, Austria
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Almeras C, Estrade V, Meria P. 2022 Recommendations of the AFU Lithiasis Committee: Endoscopic description of renal papillae and stones. Prog Urol 2023; 33:766-781. [PMID: 37918978 DOI: 10.1016/j.purol.2023.08.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/27/2023] [Accepted: 08/01/2023] [Indexed: 11/04/2023]
Abstract
Endoscopic observation is performed during treatments by flexible ureteroscopy to differentiate in situ between renal papillary abnormalities and stones based on their concordance with Daudon's morphological/composition descriptions adapted to endoscopy. These intraoperative visual analyses are now an integral part of the urinary stone disease diagnostic approach in addition to the morphological/structural and spectrophotometric analysis that remains the reference exam, but that loses information on the stone component representativeness due to the development of in situ laser lithotripsy. These are the first practical recommendations on the endoscopic description of renal papillae and stones. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendations (CPR) and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis [EAU Guidelines on urolithiasis. 2022]) and their adaptability to the French context.
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Affiliation(s)
- C Almeras
- UroSud, clinique La Croix du Sud, Quint-Fonsegrives, France.
| | - V Estrade
- Department of Urology, Bordeaux Pellegrin University Hospital, Bordeaux, France
| | - P Meria
- Service d'urologie, Hôpital Saint-Louis, AP-HP-Centre université Paris cité, Paris, France
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Bargagli M, Pinto F, De Leonardis R, Ragonese M, Totaro A, Recupero S, Vittori M, Bassi P, Gambaro G, Ferraro PM. Determinants of renal papillary appearance in kidney stone formers: An in-depth examination. Arch Ital Urol Androl 2023; 95:10748. [PMID: 36924385 DOI: 10.4081/aiua.2023.10748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/20/2022] [Indexed: 02/24/2023] Open
Abstract
OBJECTIVES The aim of this study is to investi-gate the association between the urinary metabolic milieu and kidney stone recurrence with a validated papillary evaluation score (PPLA). MATERIALS AND METHODS We prospectively enrolled 30 stone for-mers who underwent retrograde intrarenal surgery procedures. Visual inspection of the accessible renal papillae was performed to calculate PPLA score, based on the characterization of ductal plugging, surface pitting, loss of papillary contour and Randall's plaque extension. Stone compositions, 24h urine collections and kidney stone events during follow-up were collected. Relative supersaturation ratios (RSS) for calcium oxalate (CaOx), brushite and uric acid were calculated using EQUIL-2. PPLA score > 3 was defined as high. RESULTS Median follow-up period was 11 months (5, 34). PPLA score was inversely correlated with BMI (OR 0.59, 95% CI 0.38, 0.91, p = 0.018), type 2 diabetes (OR 0.04, 95% CI 0.003, 0.58, p = 0.018) and history of recurrent kidney stones (OR 0.17, 95%CI 0.04, 0.75, p = 0.019). The associations between PPLA score, diabetes and BMI were not confirmed after excluding patients with uric acid stones. Higher PPLA score was associated with lower odds of new kidney stone events during follow-up (OR 0.15, 95% CI 0.02, 1.00, p = 0.05). No other significant correla-tions were found. CONCLUSIONS Our results confirm the lack of efficacy of PPLA score in phenotyping patients affected by kidney stone disease or in predicting the risk of stone recurrence. Larger, long-term studies need to be performed to clarify the role of PPLA on the risk of stone recurrence.
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Affiliation(s)
- Matteo Bargagli
- Dipartimento Universitario di Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Roma; U.O.S. Terapia Conservativa della Malattia Renale Cronica, Dipartimento di Scienze Mediche e Chirurgiche, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma.
| | - Francesco Pinto
- U.O.C. Clinica Urologica, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma.
| | - Rossella De Leonardis
- Dipartimento Universitario di Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Roma.
| | - Mauro Ragonese
- U.O.C. Clinica Urologica, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma.
| | - Angelo Totaro
- U.O.C. Clinica Urologica, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma.
| | | | - Matteo Vittori
- Department of Urology, San Carlo di Nancy Hospital, Rome.
| | - PierFrancesco Bassi
- Dipartimento Universitario di Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Roma; U.O.C. Clinica Urologica, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma.
| | - Giovanni Gambaro
- Renal Unit, Department of Medicine, University-Hospital of Verona, Verona.
| | - Pietro Manuel Ferraro
- Dipartimento Universitario di Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Roma; U.O.S. Terapia Conservativa della Malattia Renale Cronica, Dipartimento di Scienze Mediche e Chirurgiche, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma.
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Almeras C, Pradere B, Estrade V, Meria P, French Urological Association OBOTLCOT. Endoscopic Papillary Abnormalities and Stone Recognition (EPSR) during Flexible Ureteroscopy: A Comprehensive Review. J Clin Med 2021; 10:jcm10132888. [PMID: 34209668 PMCID: PMC8267668 DOI: 10.3390/jcm10132888] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 06/18/2021] [Accepted: 06/26/2021] [Indexed: 12/29/2022] Open
Abstract
Introduction: The increasing efficiency of the different lasers and the improved performance of endoscopic devices have led to smaller stone fragments that impact the accuracy of microscopic evaluation (morphological and infrared). Before the stone destruction, the urologist has the opportunity to analyze the stone and the papillary abnormalities endoscopically (endoscopic papillary recognition (EPR) and endoscopic stone recognition (ESR)). Our objective was to evaluate the value for those endoscopic descriptions. Methods: The MEDLINE and EMBASE databases were searched in February 2021 for studies on endoscopic papillary recognition and endoscopic stone recognition. Results: If the ESR provided information concerning the main crystallization process, EPR provided information concerning the origin of the lithogenesis and its severity. Despite many actual limitations, those complementary descriptions could support the preventive care of the stone formers in improving the diagnosis of the lithogenesis mechanism and in identifying high-risk stone formers. Conclusion: Until the development of an Artificial Intelligence recognition, the endourologist has to learn EPSR to minimize the distortion effect of the new lasers on the stone analysis and to improve care efficiency of the stone formers patients.
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Affiliation(s)
- Christophe Almeras
- Department of Urology, La Croix du Sud Clinic-RGDS, UroSud, 52 bis Chemin de Ribaute, Boite 301, 31130 Quint Fonsegrives, France
- French Urological Association (AFU), La Maison de l’Urologie, 11 rue Viète, 31017 Paris, France; (V.E.); (P.M.);
- Correspondence: ; Tel.: +33-53-202-7202; Fax: +33-53-202-7203
| | - Benjamin Pradere
- Department of Urology, Comprehensive Cancer Center, Medical University of Vienna, 1090 Vienna, Austria;
| | - Vincent Estrade
- French Urological Association (AFU), La Maison de l’Urologie, 11 rue Viète, 31017 Paris, France; (V.E.); (P.M.);
- Department of Urology, CHU Pellegrin, 33300 Bordeaux, France
| | - Paul Meria
- French Urological Association (AFU), La Maison de l’Urologie, 11 rue Viète, 31017 Paris, France; (V.E.); (P.M.);
- Department of Urology, Saint Louis Hospital, Denis Diderot University, 75010 Paris, France
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Almeras C, Daudon M, Estrade V, Gautier JR, Traxer O, Meria P. Classification of the renal papillary abnormalities by flexible ureteroscopy: evaluation of the 2016 version and update. World J Urol 2020; 39:177-185. [PMID: 32193654 PMCID: PMC7858204 DOI: 10.1007/s00345-020-03149-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Accepted: 02/26/2020] [Indexed: 11/18/2022] Open
Abstract
Introduction To assess the use of the 2016 proposed classification of the renal papillary abnormalities during flexible ureteroscopy that aims to standardize their description. Patients and methods We performed a prospective monocentric single operator collection of the data using this classification during 88 consecutive flexible ureteroscopies required for renal stones treatment. Outcome measurements and statistical analysis: data of stones analysis (microscopy and infrared spectrophotometry) and of serum and urines biochemical samples have been compared with the results of the classified endoscopic descriptions. Results Mean duration of description was 81.4 s. We reported that 83% of the patients had Randall plaques (RP), as only 4.5% of the patients had no abnormality. Concerning the papillary stones and anchored stones were observed in 30.7% and aspect of intraductal crystallization (Sc) in 15.9%. Erosions were present in 55.7% and extrophic papillae in 8%. Sa1 and Pa2 were significantly correlated to RP, anchored stones (Sa) to papillary erosions and calcium phosphate stones to intraductal crystallization. Hypercalciuria was significantly higher in Sa2 than Sa1 stones. Conclusions The different descriptions in the 2016 classification were confirmed by the results of this study. Papillary abnormalities are consequences of stones development. Their descriptions could also improve the follow-up and the diagnosis of a metabolic lithogenesis. We recommend their systematic description during ureteroscopy. Some improvements are proposed to update this classification.
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Affiliation(s)
- Christophe Almeras
- Department of Urology, La Croix du Sud Clinic, 52 chemin de Ribaute, 31130, Quint Fonsegrives, France.
| | - Michel Daudon
- Unit of Functional Explorations, Tenon Hospital, Pierre and Marie Curie University, Paris, France
| | | | - Jean Romain Gautier
- Department of Urology, La Croix du Sud Clinic, 52 chemin de Ribaute, 31130, Quint Fonsegrives, France
| | - Olivier Traxer
- Department of Urology, Tenon Hospital, Pierre and Marie Curie University, Paris, France
| | - Paul Meria
- Department of Urology, Saint-Louis Hospital, Denis Diderot University, Paris, France
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Fernandez K, Korinek M, Camp J, Lieske J, Holmes D. Automatic detection of calcium phosphate deposit plugs at the terminal ends of kidney tubules. Healthc Technol Lett 2019; 6:271-274. [PMID: 32038870 PMCID: PMC6952263 DOI: 10.1049/htl.2019.0086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 10/02/2019] [Indexed: 11/20/2022] Open
Abstract
Kidney stones are a common urologic condition with a high amount of recurrence. Recurrence depends on a multitude of factors the incidence of precursors to kidney stones, plugs, and plaques. One method of characterising the stone precursors is endoscopic assessment, though it is manual and time-consuming. Deep learning has become a popular technique for semantic segmentation because of the high accuracy that has been demonstrated. The present Letter examined the efficacy of deep learning to segment the renal papilla, plaque, and plugs. A U-Net model with ResNet-34 encoder was tested; the Letter examined dropout (to avoid overtraining) and two different loss functions (to address the class imbalance problem. The models were then trained in 1666 images and tested on 185 images. The Jaccard-cross-entropy loss function was more effective than the focal loss function. The model with the dropout rate 0.4 was found to be more effective due to its generalisability. The model was largely successful at delineating the papilla. The model was able to correctly detect the plaques and plugs; however, small plaques were challenging. Deep learning was found to be applicable for segmentation of an endoscopic image for the papilla, plaque, and plug, with room for improvement.
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Affiliation(s)
- Katrina Fernandez
- Biomedical Imaging Resource, Mayo Clinic, Rochester, MN, USA
- University of Minnesota, Minneapolis, MN, USA
| | - Mark Korinek
- Biomedical Imaging Resource, Mayo Clinic, Rochester, MN, USA
| | - Jon Camp
- Biomedical Imaging Resource, Mayo Clinic, Rochester, MN, USA
| | - John Lieske
- Department of Nephrology & Hypertension, Mayo Clinic, Rochester, MN, USA
| | - David Holmes
- Biomedical Imaging Resource, Mayo Clinic, Rochester, MN, USA
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Pless MS, Williams JC, Andreassen KH, Jung HU, Osther SS, Christensen DR, Osther PJS. Endoscopic observations as a tool to define underlying pathology in kidney stone formers. World J Urol 2019; 37:2207-2215. [PMID: 30610358 PMCID: PMC6679988 DOI: 10.1007/s00345-018-02616-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 12/23/2018] [Indexed: 11/03/2022] Open
Abstract
PURPOSE Advancements in endoscopy offer the possibility of inspection of intrarenal anatomy and pathology. The aim of the study was to evaluate renal papillary appearance in kidney stone formers and to correlate papillary findings with stone type and patient metabolic data. MATERIALS AND METHODS A consecutive cohort of 46 kidney stone formers undergoing retrograde intrarenal surgery was enrolled. During surgery, renal papillae were characterized in the domains of ductal Plugging (DP), surface Pitting, Loss of papillary contour, and Amount of Randall's plaque (RP, PPLA scoring). Stone material was analyzed using micro-CT and infrared spectroscopy, and blood and urine were collected for metabolic evaluation. RESULTS In all patients, renal papillae had changes in at least one of the domains of the PPLA score. Examining the total population, it was evident that patients with predominantly plugging (DP > 0) all had very low RP scores. There were no significant trends between mean PPLA scores and urinary analytes for the total group. CONCLUSION Efforts to prevent renal stone formation have so far been insufficient in majority of patients. Digital endoscopy reveals that kidney stone formers have different and distinct papillary morphologies that seem to be linked to specific stone-forming pathways. Since renal papillary abnormalities may be easily identified during endoscopy, this may in the future prove to be an important method for tailoring prevention strategies in kidney stone patients.
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Affiliation(s)
- Maria Sloth Pless
- Urological Research Center (URC), Department of Regional Health Research, University of Southern Denmark, Vejle, Denmark
| | - James Caldwell Williams
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Kim Hovgaard Andreassen
- Urological Research Center (URC), Department of Regional Health Research, University of Southern Denmark, Vejle, Denmark
- Department of Urology, Lillebaelt Hospital, Beriderbakken 4, Vejle, Denmark
| | - Helene Ulrich Jung
- Urological Research Center (URC), Department of Regional Health Research, University of Southern Denmark, Vejle, Denmark
- Department of Urology, Lillebaelt Hospital, Beriderbakken 4, Vejle, Denmark
| | | | | | - Palle Jörn Sloth Osther
- Urological Research Center (URC), Department of Regional Health Research, University of Southern Denmark, Vejle, Denmark.
- Department of Urology, Lillebaelt Hospital, Beriderbakken 4, Vejle, Denmark.
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Borofsky MS, Williams JC, Dauw CA, Cohen A, Evan AC, Coe FL, Worcester E, Lingeman JE. Association Between Randall's Plaque Stone Anchors and Renal Papillary Pits. J Endourol 2019; 33:337-342. [PMID: 30793930 DOI: 10.1089/end.2018.0589] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Renal papillary pits are commonly encountered during ureteroscopy. The mechanism by which such pits arise is unclear. One hypothesis is that pits represent sites where stones overgrowing Randall's plaque (RP) were dislodged. We sought to examine this theory by using digital ureteroscopy and stone μCT. MATERIALS AND METHODS Patients undergoing endoscopic stone removal had procedures recorded and stones analyzed by using μCT. Stones with evidence of Randall's plaque anchors (RPAs) were identified in a blinded fashion. Surgical videos were reviewed independently by two urologists. RESULTS Twenty-eight patients had μCT-confirmed stones with RPA. Among them, 93% were recurrent stone formers and 75% had had prior stone procedures. Metabolic abnormalities were present in 87%, with 79% classified as idiopathic calcium oxalate stone formers. A mean of 7.6 stones with RPA were identified per procedure. In each case, papillary pits were visualized before any stone manipulation and in several cases the active dislodgement of an attached stone led to immediate identification of an underlying pit. Such stones routinely demonstrated an RPA on μCT. The average depth of RPA was 302 ± 172 μm, consistent with the corresponding shallow pits visualized on the papillary surface. CONCLUSIONS Stones overgrowing RP are capable of pulling away a piece of papilla when dislodged, resulting in a visible papillary pit. This process manifests as an RPA on the undersurface of the stone and a papillary pit on the corresponding area of attachment. Identification of pits may help identify patients who form stones primarily by the RP mechanism.
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Affiliation(s)
- Michael S Borofsky
- 1 Department of Urology, University of Minnesota, Minneapolis, Minnesota
| | - James C Williams
- 2 Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Casey A Dauw
- 3 Department of Urology, University of Michigan, Ann Arbor, Michigan
| | - Andrew Cohen
- 4 Section of Urology, Department of Surgery, University of Chicago, Chicago, Illinois
| | - Andrew C Evan
- 2 Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Fredric L Coe
- 5 Department of Nephrology, University of Chicago, Chicago, Illinois
| | - Elaine Worcester
- 5 Department of Nephrology, University of Chicago, Chicago, Illinois
| | - James E Lingeman
- 6 Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana
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Abstract
PURPOSE OF REVIEW The pathophysiological mechanisms in kidney stone formation are insufficiently understood. In order to achieve a better understanding of the complexity of stone formation, studies evaluating anatomical variations in the renal papillae have been performed. This review intends to illuminate recent findings. Moreover, new techniques to improve the understanding and interpretation of crystallization mechanisms are reviewed. RECENT FINDINGS Due to improvements of digital ureteroscopes, detailed endoscopic mapping of renal papillae is now possible. Connections between papillary morphology and histopathological changes in different subsets of stone formers have been documented. The formation of kidney stones seems to take place in relation to Randall's plaques, Ducts of Bellini or by free formation. Additionally, theories of kidney stone formation because of vascular injury or inflammatory events in the papillae have been suggested. SUMMARY Novel techniques including improved digital endoscopic visualization, microcomputed tomography (CT), electron microscopy and energy dispersive compositional analyses of kidney stones seem essential in the search for effective and reliable methods to understand stone forming processes, which ultimately should result in effective measures for more personalized stone prevention strategies in the future.
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