pediatric kidney pathology

congenital hydronephrosis can occur as a result of several conditions including:

• ureteropelvic junction obstruction

• vesicoureteral reflux (VUR)

• posterior urethral valves

• prune belly syndrome

what is the most common cause of congenital hydronephrosis in infants and children?

ureteropelvic junction obstruction

clinical findings of a ureteropelvic junction obstruction:

• palpable abdominal mass

• abdominal distention

• hematuria

sonographic findings of a ureteropelvic junction obstruction:

• dilated renal collecting system

• distal ureter not seen

vesicoureteral reflux (VUR)

the backward flow of urine from the urinary bladder into the ureter and possibly all the way back to the kidney

VUR is commonly caused by:

an abnormal angle of insertion of the distal ureter into the bladder at the ureterovesicle junction, resulting in a faulty valve

clinical findings of VUR:

• may be asymptomatic

• unexplained fever

• irritability

• flank pain

• leukocytosis

• bacteriuria

• hematuria

• dysuria

• urgency to void

• UTI

• proteinuria

sonographic findings of VUR:

• patients with minimal reflux, kidneys may appear normal

• hydronephrosis and/or hydroureter may be present

• ureterocele may be seen in the bladder

• bladder debris may be seen

• hydronephrosis may be present and may reduce after micturition

• possible scar formation in the kidneys

grade I VUR:

urine refluxes into the ureter only

grade II VUR:

urine refluxes into the ureter and the renal pelvis without hydronephrosis

grade III VUR:

urine refluxes into the ureter and the renal pelvis with hydronephrosis

grade IV VUR:

moderate hydronephrosis

grade V VUR:

severe hydronephrosis

in patients that have duplicated pelvicaliceal systems and complete ureteral duplication, the upper pole moiety in the duplex kidney is often prone to:

obstruction because of an irregular insertion of the ureter into the urinary bladder which leads to the development of an obstructing ureterocele

in patients that have duplicated pelvicaliceal systems and complete ureteral duplication, the lower pole moiety in the duplex kidney is often prone to:

reflux

the assumption about the obstruction and refluxing components of the duplicated system is referred to as the:

Weigert-Meyer rule

what are other exams that can be performed to provide a more definitive diagnosis of VUR?

• voiding cystourethrogram

• nuclear cystogram

mild VUR is typically treated with:

antibiotics

severe VUR is treated with:

• surgical intervention

• use of a synthetic bulking agent that is injected endoscopically → subureteric Teflon injection (STING)

how do STING agents work in the treatment of VUR?

they elevate the ureteral orifice and distal ureter, allowing for the normal flow of urine from the ureter into the bladder

sonographic appearance of STING agents:

appears as a hyperechoic structure in the area of the vesicoureteral junction that may produce acoustic shadowing

posterior urethral valves

folds of excessive urethral tissue found exclusively in males

clinical findings of posterior urethral valves:

• male patient

• UTI

• voiding abnormalities

sonographic findings of posterior urethral valves:

• large urinary bladder

• dilated ureters

• dilated bilateral renal collecting systems

prune belly syndrome

• caused by megacystis → massively dilated urinary bladder

• seen mostly in male fetuses

• results from a urethral abnormality which leads to a bladder outlet obstruction

prune belly describes the result of:

the abdominal wall musculature being stretched by the extremely enlarged urinary bladder

the triad of characteristics that is consistent with the diagnosis of prune belly syndrome includes:

• absent abdominal musculature

• undescended testis

• urinary tract abnormalities

clinical findings of prune belly syndrome:

• often discovered in utero

• UTI

• failure to thrive

sonographic findings of prune belly syndrome:

• large urinary bladder

• varying degrees of hydronephrosis

• varying degrees of ureteral dilation

what is the most common solid malignant pediatric abdominal mass?

Wilms tumor/nephroblastoma

at what age is a Wilms tumor typically discovered?

before the age of 5, with a mean age of 3

Wilms tumors can grow large and invade what other structures?

renal vein and IVC

pediatric patients with what syndrome have a tendency to develop a Wilms tumor?

Beckwith-Wiedemann syndrome

clinical findings of a Wilms tumor:

• palpable abdominal mass

• abdominal pain

• hematuria

• fever

• HTN

sonographic findings of a Wilms tumor:

• large, solid, mostly echogenic masses that may contain anechoic or hypoechoic areas

• may also be isoechoic

urachus

• a remnant of embryologic development

• a tubular structure that extends from the umbilicus to the apex of the bladder

• failure of it to close can result in a urachal anomaly

urachal anomalies include:

• patent urachus (urachal fistula)

• urachal cyst

• urachal sinus

• urachal diverticulum

clinical findings of urachal anomalies:

• possible signs of UTI

• palpable abdominal mass between the umbilicus and the urinary bladder

sonographic findings of urachal anomalies:

• patent urachus will appear as an anechoic tube that extends from the umbilicus to the apex of the urinary bladder

• urachal cyst and urachal diverticulum will appear as a cystic structure between the bladder and the umbilicus

• urachal sinus will appear as a linear, fluid-filled structure that is continuous with with umbilicus