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 (SF). Materials and Methods From 2009 to 2014, patients undergoing percutaneous nephrolithotomy were prospectively enrolled in our study. Endoscopic analysis and biopsy of papillae was 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 SF to compare with 90 idiopathic CaOx SF and 17 controls. On endoscopic mapping, 28 struvite SF (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 SF (3.7 ±4.3%, p=0.0018) and similar to controls (1.7 ±2.7%, p=0.76). Average mean plug SA was similar between struvite SF, CaOx SF, and controls. On metabolic assessment, 83% of struvite SF had at least one urine abnormality, with urinary uric acid and oxalate levels significantly higher among struvite SFs compared to controls (p=0.002 ). Despite lack of active UTI, interstitial inflammation was more prevalent in struvite SF compared to CaOx SF (43.5% vs 7.3%, p=0.0001). Conclusions Our findings suggest a limited role for Randall's plaque in struvite stone formation. Struvite SF have less plaque formation than CaOx SF, but demonstrate evidence of severe parenchymal inflammation compared to other stone formers. The role of this prominent interstitial inflammation requires further study.

Endoscopic observations as a tool to define underlying pathology in kidney stone formers

“…The only consistent finding in the struvite group was LC, which may correlate to interstitial inflammation as demonstrated in a recent study [26]. In line with our data, their findings suggest that RP has a limited role for struvite stone formation and an alternate pathogenic mechanism is thus implicated [26].…”

Current insights into the mechanisms and management of infection stones

“…Different from other types of urinary stones, the physicochemical processes that lead to infection stone formation are largely driven by the presence of ureolytic microorganisms in the urinary tract system. randall's plaque has been suggested to have a key role in the lithogenesis of calcium oxalate stones 69 , but seems to have a limited role in struvite stone formation 70 . Indeed, Jaeger et al 70 reported substantially lower levels of Randall's plaque formation in struvite stone formers than in calcium oxalate stone formers.…”

“…randall's plaque has been suggested to have a key role in the lithogenesis of calcium oxalate stones 69 , but seems to have a limited role in struvite stone formation 70 . Indeed, Jaeger et al 70 reported substantially lower levels of Randall's plaque formation in struvite stone formers than in calcium oxalate stone formers. Owing to the lack of or low abundance of Randall's plaque, the authors suggested that struvite formation is probably independent of the presence of Randall's plaque.…”

Integration and utilization of modern technologies in nephrolithiasis research

“…Papillary appearance might also provide unique information in instances where the stones are not believed to originate from the papilla. For example, papillary appearance in stone formers that form struvite 34 or uric acid stones 35 is distinct from that of individuals who do not form stones. Currently, our understanding of the clinical significance of papillary abnormalities remains limited, although the advent of high-definition renal endoscopy opens many opportunities for future investigations in this area.…”