Renal Cysts in the Pediatric
Population: When to Operate
Maahum Haider
Seattle Children’s Hospital
General Surgery
Introduction
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The kidney is one of the most common sites in the
body for cysts
Renal cysts in children can be associated with
normally functioning kidneys, or they can be the
result of serious genetic abnormalities as part of a
syndrome, sometimes resulting in ESRD
The decision to operate depends on symptoms,
prognosis and underlying cause and is aided by
radiological studies; most commonly ultrasound and
CT
Cystic Diseases of the Kidney
Non-heritable
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Simple cysts
Acquired Renal Cystic
disease
Multicystic dysplastic
kidneys
Sporadic glomerulocystic
disease
Spectrum of multilocular
cysts
Heritable
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ARPKD
ADPKD
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Nephronopthisis
Medullary cystic disease
Congenital nephrosis
Familial hypoplastic
glomerulocystic disease
Multiple malformation
syndromes
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Tuberous sclerosis, VHL
Bosniak Classification
Category I
Simple benign cyst with (1) good through-transmission (i.e.,
acoustic enhancement), (2) no echoes within the cyst, (3) sharply,
marginated smooth wall; requires no surgery.
Category II
Looks benign with some radiologic concerns including septation,
minimal calcification, and high density; requires no surgery.
Category IIF
Although calcification in wall of cyst may even be thicker and more
nodular than in category II, the septa have minimal enhancement,
especially those with calcium; requires no surgery.
Category III
More complicated lesion that cannot confidently be distinguished
from malignancy, having more calcification, more prominent
septation of a thicker wall than a category II lesion; more likely to
be benign than malignant; requires surgical exploration and/or
removal.
Category IV
Clearly a malignant lesion with large cystic components, irregular
margins; solid vascular elements; requires surgical removal.
Campbell-Walsh, 9th Ed.
Simple Cysts
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Very rare in pediatric population (0.22%)
Most arise from nephrons and collecting ducts (widened
area, diverticulum or isolated sac)
Often found incidentally in association with other urinary
tract anomalies
If symptomatic, presenting features may include abdominal
pain, hematuria, or obstruction from peri-pelvic cysts
Ultrasound is diagnostic test of choice.
If indeterminate, CT with IV contrast is the next step
Simple Cysts
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Should not be overlooked as they may be an early
presentation of ADPKD
Most can be managed conservatively with US follow
up
If patient is symptomatic, cysts can be aspirated and
injected with sclerosant to prevent re-accumulation
Recalcitrant cysts can be treated with percutaneous
resection, intrarenal marsupialization or laparoscopic
unroofing
Acquired Renal Cysts
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Found to be a feature of ESRD
Duration of dialysis is directly proportional to number
and size of cysts
Successful transplantation often results in regression
of the cysts
If cyst is infected, percutaneous drainage may be
considered
If heparinization for dialysis is associated with
significant hematuria, embolization or nephrectomy
may be indicated
Multicystic Dysplastic Kidney
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Most frequent cystic disease in newborn
Renal maldevelopment with diffuse
cysts: “bunch of grapes” appearance on
US
Often associated with abnormalities of
contralateral urinary tract (UPJ
obstruction, VUR)
Prophylactic nephrectomy has been suggested to avoid
malignant transformation but this is very rare (1:2000)
Long term follow up with US shows that most become
smaller or stay the same size.
Very few enlarge and it is up to the surgeon’s discretion to
remove it
Multilocular cysts
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Represent a spectrum of conditions that has been described as a
continuum in children:
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Cystic nephroma
Cystic partially differentiated nephroblastoma
Multilocular cyst with nodules of Wilms
Cystic Wilms
Qualify as complex renal cysts on CT, suspicious for malignancy
(Bosniak III-IV)
Multilocular Cysts
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Two main operative concerns:
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Is the contralateral urinary tract normal?
Is the abnormal kidney involved with Wilms’ tumor?
Currently no reliable means of ruling out malignancy
without histopathology and therefore warrants
nephrectomy
If enucleation or partial nephrectomy is chosen,
recurrence is possible
Conclusions
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There are many different etiologies of renal cysts
Some can simply be observed and go by unnoticed,
while others require surgical intervention and
extensive medical management
The Bosniak classification aids in determining which
cysts can be managed expectantly and which require
surgical exploration or excision
Main operative considerations include patient’s
symptoms, natural history of disease process, and
abnormalities in contralateral urinary tract that may
need to be addressed or repaired prior to surgery
References
Management of simple renal cysts in children
G.V.S. MURTHI, A.F. AZMY and A.G. WILKINSON*
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Departments of Paediatric Surgery and *Paediatric Radiology, Royal Hospital for Sick
Children, Glasgow G3 8SJ, UK
Current Diagnosis and Treatment: Surgery
Chapter 43. Pediatric Surgery
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Simple Renal Cysts in Children
P G Ransley FRCS
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The Hospital for Sick Children, London
Campbell-Walsh Urology
Section XVII: Pediatric Urology
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