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Renal cyst evolution in childhood: a contemporary observational study
C Rediger1, L A Guerra1, M A Keays1
1Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada; Division of Urology, Department of Surgery, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada.
Insights
Children with simple renal cysts rarely develop polycystic kidney disease (PKD) or malignancy. Routine ultrasound monitoring beyond 2-3 years for these benign childhood cysts is likely unnecessary, optimizing medical resource use.
Area of Science:
- Pediatric Nephrology
- Medical Imaging
- Urology
Background:
- Children with renal cysts undergo ultrasound (US) monitoring to detect potential malignant transformation or polycystic kidney disease (PKD).
- The clinical utility and necessity of ongoing surveillance for these cysts remain uncertain.
- Simple or minimally complex renal cysts are common findings in pediatric populations.
Purpose of the Study:
- To evaluate the natural history of simple or minimally complex renal cysts in children.
- To determine the proportion of these cysts that progress to autosomal dominant polycystic kidney disease (ADPKD), autosomal recessive polycystic kidney disease (ARPKD), or malignancy.
- To inform clinical guidelines regarding the surveillance of pediatric renal cysts.
Main Methods:
- Retrospective chart review of patients with renal cysts diagnosed between 2004 and 2014.
- Inclusion criteria: ≤3 simple or minimally complex cysts on initial US, without prior diagnosis of specific kidney conditions or malignancy.
- Logistic regression analysis to identify factors associated with ADPKD/ARPKD development.
Main Results:
- Eighty-seven eligible pediatric patients were included, with a median follow-up of 4.1 years.
- 12.6% were diagnosed with ADPKD and 1.2% with ARPKD, with diagnoses occurring early in the follow-up period.
- No patients developed malignancy, and most cysts did not require intervention.
Conclusions:
- Children with few simple or minimally complex renal cysts typically do not require extensive long-term monitoring.
- Progression to PKD or malignancy is rare, suggesting that current surveillance protocols may be excessive.
- Further research should focus on refining guidelines for optimal follow-up of pediatric renal cysts.
Introduction:
Children with renal cysts often undergo ultrasound (US) monitoring to identify malignant transformation or polycystic kidney disease (PKD). However, the utility of ongoing surveillance is uncertain.
Objective:
The objective of this study was to assess the natural history of simple or minimally complex cysts and the proportion of progression to autosomal dominant polycystic kidney disease (ADPKD), autosomal recessive polycystic kidney disease (ARPKD), or malignancy.
Study Design:
The institutional review board approved retrospective chart review at one institution between 2004 and 2014. Eligible patients had ≤3 simple or minimally complex cyst(s) discovered on US without an initial diagnosis of multicystic dysplastic kidney, genitourinary malignancy, ADPKD, or ARPKD. Patient demographics and cyst details were recorded at identification and follow-up visits. Logistic regression was used to examine univariate association between diagnosis of ADPKD/ARPKD and each recorded variable.
Results:
Eighty-seven eligible patients were identified. Twenty-two patients were identified antenatally or in the first year of life; the remaining 65 were identified at >1 year of age, median 7.6 years (interquartile range [IQR]: 4.2, 10.6). Most (60/87, 69%) had a solitary cyst at initial US. The median length of follow-up was 4.1 years (IQR: 1.9, 6.8) with median 3 follow-up US (IQR: 2, 5). Eleven patients (12.6%) were diagnosed with ADPKD. One patient (1.2%) was diagnosed with ARPKD. A median 2 follow-up US (IQR: 1, 4) procedures were performed over a median of 2.2 years (IQR: 1.0, 3.9) to obtain diagnoses of ADPKD or ARPKD. No patients developed malignancy.
Discussion:
This study's results reveal that children identified to have a small number of simple or minimally complex renal cysts on initial US are unlikely to require additional treatment for these cysts as transformation to PKD or malignant condition is rare. Supporting this are results from literature that although simple cysts in childhood may evolve over time, most do not require any surgical or invasive treatment in the long term. Limitations include retrospective design and single institution.
Conclusions:
Autosomal dominant polycystic kidney disease/autosomal recessive polycystic kidney disease diagnosis occurs early in follow-up evaluation in children with simple or minimally complex cysts. Malignant transformation did not occur in any patients in this study.
Patient Summary:
This study examines the natural history of renal cysts in childhood. Following up simple renal cysts routinely beyond 2-3 years after initial detection may not be optimal due to the use of limited medical resources.
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