Login to Access Video or Poster Abstract: MP19-17
Sources of Funding: none

Introduction

Randall's plaque (RP) with attached stones is recognized as a primary mechanism for stone formation in adult calcium oxalate stone formers (CaOx SF). The role of RP in pediatric stone pathogenesis is unknown, with no reported studies to date. The purpose of this study is to investigate renal papillary abnormalities and quantify RP in pediatric CaOx SF.

Methods

8 pediatric CaOx SF underwent ureteroscopy for symptomatic urolithiasis. The collecting system was mapped using a digital ureteroscope. Video for each patient was then reviewed using a retrograde pyelogram to confirm the location of each papilla. A single investigator (NLM) reviewed the video to quantify RP and other papillary abnormalities such as pitting and Bellini duct plugs. Each papilla was graded as having mild (<10%), moderate (10-50% ), or severe (>50% ) amount of RP. Patient history was recorded.

Results

An average of 9 papillae were mapped per patient. RP was present in 100% of patients and in 88.8% (64/72) of all papillae examined. When present, RP was uniformly distributed throughout the kidney without preferential distribution to a region or pole. The amount of RP on the papillae was graded as mild in 60%, moderate in 20.8%, and severe in 8.3% (Table 1). Other papillary abnormalities were rare in pediatric SF with Bellini duct plugging in 9.7% and pitting in 15.2% papillae. No correlation was found between the amount of plaque and age at first stone or number of prior stones (p= 0.84). Attached stones were rare (1/8 patients). The two patients with severe RP had a small amount of calcium phosphate in their stone analysis.

Conclusions

RP is common in pediatric CaOx SF, while pitting and Bellini duct plugging are not. Compared to adult CaOx SF where up to 75% of stones are found attached to RP, attached stones were rare. The significance of these findings in pediatric stone pathogenesis remains uncertain in this early report, however ongoing research to include correlation with 24 hr urine data and stone recurrence is currently underway.

Funding

none