tullus et al .   recently published an algorithm for the orderly investigation of renovascular hypertension in children , in which ultrasonography is one of the primary studies .
doppler ultrasound non - invasively assesses renal artery flow , but is less sensitive than angiography .
computed tomographic ( ct ) angiography and magnetic resonance angiography ( mra ) offer intermediate sensitivity .
digital subtraction angiography is the gold standard investigation for renovascular causes . in some children , hypertension accompanies congenital renal anomalies or an ectopic renal position . in some reports , magnetic resonance imaging ( mri ) or retrograde pyelography led to the diagnosis when ultrasound failed to do so [ 2 , 3 ] .
when ectopia does occur , the thorax is an unusual location to find the kidney .
hahn et al .   described an intrathoracic kidney and postulated that contact with the diaphragm was the direct cause of malformation of the diaphragm .
the obstruction of urinary drainage is believed to cause dysplasia and is associated with well - described pathological findings .
obstruction , however , is not believed to play a role in ectopia ; yet , malformations often accompany ectopia . here , we report a child with hypertension and a malformed kidney in an unexpected location .
we describe the use of new modalities for imaging and surgical correction , as well as pathologic findings that have not previously been described in this context .
the 95th percentile pressure for her height and age were 108/70 . over the next few weeks , auscultated pressures ranged between 108128 mmhg ( systolic ) and 7688 mmhg ( diastolic ) .
the second , a twin gestation , was terminated at 17 weeks due to neural tube defects in both fetuses and cardiac anomalies in one of them . to treat a hypercoagulable state during this and a fourth pregnancy , the mother received low - molecular - weight heparin and aspirin .
growth and development were normal , with a height and weight at the 50th percentile .
peripheral renin activity was 3.5 ng / ml / h ( < 15 ng / ml / h ) .
her urine - specific gravity was 1.010 , ph 7 , with no heme , protein , nitrite or glucose .
a renal ultrasound revealed the left kidney to be 8.1 cm in length ( between the 50th and 95th percentiles ) .
a nuclear renal scan demonstrated the normal uptake of nucleotide within the left kidney ( figure 1 ) .
however , synchronous with activity in the left kidney , a focus of abnormal activity appeared superiorly in either the lower aspect of the right hemithorax or the uppermost aspect of the abdomen . 

though displacement of the ectopic kidney and bowel into the thorax was noted , imaging did not clarify whether a bochdalek hernia existed or an eventration of the hemidiaphragm . 

2.time-resolved , dynamic contrast - enhanced mra of the chest and abdomen . 
 fig .
a small right renal artery ( solid arrow ) arises from the aorta ( a ) , coursing first laterally , then cranially .
an aneurysm ( open arrow ) is seen near the upward inflection of the vessel .
a small right renal artery ( solid arrow ) arises from the aorta ( a ) , coursing first laterally , then cranially .
an aneurysm ( open arrow ) is seen near the upward inflection of the vessel .
echocardiography revealed dilation of the aortic root and ascending aorta , with a small patent ductus arteriosus . left ventricular mass / height was 41.8 g / m ( normal 19.438.6 ) .
enalapril was begun at 0.08 mg / kg and gradually increased to 0.35 mg / kg , while monitoring serum electrolytes and creatinine . noting no change in blood pressures ( 118122 mmhg systolic ) , the patient began losartan , which was increased gradually from 0.9 to 1.8 mg / kg .
enalapril was discontinued due to sleepiness , resolving this symptom . though pressures improved somewhat ( average systolic pressure of 115 mmhg ) , she still did not maintain pressures below the 90th percentile ( 104 mmhg ) .
amlodipine was begun and titrated up to 0.5 mg / kg / day . though the patient remained asymptomatic , it appeared unlikely that pressures could be normalized on a simple regimen without adverse effects .
a right - sided diaphragmatic eventration was present with a very thin connective tissue sac that functioned as an elevated diaphragm , keeping the abdominal contents separate from the chest .
( a very thin hernia sac functioned as an elevated diaphragm , keeping the abdominal contents separate from the chest . )
intraoperatively , the surgeons considered whether to place a synthetic patch in place of the missing diaphragm .
noting her normal pulmonary function tests , they elected to defer action on the diaphragm until a later time .
both anti - hypertensives were held on the evening prior to surgery . in the immediate post - operative period ,
four hours post - operatively , resting blood pressures were 125/75 , and she received 0.25 mg / kg amlodipine .
she vomited 20 min after the dose , but pressures improved to 102/52 . at discharge
( 18 h later ) , this dose was continued once daily . the drug was weaned and discontinued within 3 weeks .
pathology revealed a hypoplastic immature kidney measuring 5  3  2 cm and weighing 15 g ( expected weight for age 60 g ) . the collecting system and medullary pyramids showed no evidence of obstructive uropathy .
the renal cortex showed hypoplasia with some glomerular immaturity and moderate glomerulosclerosis and patchy tubulo - interstitial atrophy ( figure 4 ) .
the main renal artery was small and the wall showed moderate medial hypertrophy . also noticed was the presence of prominent smooth muscle nodules surrounding the artery and some of its main branches ( figures 46 ) .
although blood pressures in our patient were modestly elevated , such changes can be found within end - stage kidneys and are attributed to severe hypertensive damage to arteriolar walls .
this suggests the presence of intermittent unkinking of the proximal artery with high pressures reaching the distal renal artery .
the renal cortex showed hypoplasia with some glomerular immaturity and moderate sclerosis and patchy tubulo - interstitial atrophy ( figure 6 ) .
intrarenal arteries and arterioles displayed moderate luminal narrowing due to medial hypertrophy ; however , fibrinoid necrosis , onion - skinned arterioles and juxtaglomerular apparatus abnormalities were absent . 

4.a cross - section view of the distal renal artery which shows medial hypertrophy and florid peri - arterial  fibroid - like smooth muscle nodules ( he 40 ) . 

5.bundles of smooth muscle cells streaming from the artery wall ( a ) to form peri - arterial fibroid - like nodule ( n ) .
focal lymphocytes and fibrous tissue were also noted ( open star ) ( he 100 ) . 

6.light microscopy of the renal cortex showing medial arteriolar hypertrophy with luminal narrowing ( oval ) .
glomeruli vary from normal ( n ) to sclerosed ( circle ) , while others show immaturity with persistent epithelial cell prominence ( i m ) ( he 200 ) . a cross - section view of the distal renal artery which shows medial hypertrophy and florid peri - arterial  fibroid - like smooth muscle nodules ( he 40 ) .
bundles of smooth muscle cells streaming from the artery wall ( a ) to form peri - arterial fibroid - like nodule ( n ) .
focal lymphocytes and fibrous tissue were also noted ( open star ) ( he 100 ) .
light microscopy of the renal cortex showing medial arteriolar hypertrophy with luminal narrowing ( oval ) .
glomeruli vary from normal ( n ) to sclerosed ( circle ) , while others show immaturity with persistent epithelial cell prominence ( i m ) ( he 200 ) .
this patient 's ultrasound did not reveal a small , scarred or dysmorphic kidney to suggest an explanation for the hypertension . analyzing this case prospectively
captopril - augmented renal scanning or angiography can assess for vascular abnormalities , but the sensitivity of captopril scans has been criticized .
the left kidney 's large size was thought to indicate compensatory growth , suggesting that the right kidney had been abnormal or absent for most or all of her life .
since an ectopic kidney might not appear reniform nor be of normal size , a functional nuclear medicine study was performed .
valentini et al .   described hypertension attributed to a unilateral , malformed kidney . in that case , the defect was detected by mri when control of pressures proved to be suboptimal after 1 year of pharmacologic therapy .
ilyas and tolaymat   described a patient in whom only retrograde pyelography enabled the detection of the abnormal kidney . in our patient ,
an initial renal ultrasound failed to detect the right kidney , and therefore , looking for an abnormal kidney within the physiologic location would not have succeeded . in this case , the abnormal kidney had sufficient function to enable detection by nuclear imaging , evident from her peripheral renin activity and aldosterone levels .
scintigraphic uptake in the right chest was amorphous , making it impossible to define the limits of the organ or to measure differential function .
in this case , nuclear imaging attracted attention to an unlikely place in which a missing kidney could be found . though angiography is the gold standard for defining renal arteries and collateral vessels , it is infrequently used in pediatrics due to its invasiveness .
mra has become more useful as it becomes possible to visualize smaller vessels . in children ,
ct angiography permits more rapid image acquisition , sometimes enabling studies without sedation , but with significant radiation exposure . prior to 2007
, it was not possible to obtain the dynamic , contrast - enhanced time - resolved angiography used in this case .
prenatal ultrasounds did not prospectively detect the diaphragmatic eventration , ectopic renal position nor the abnormal renal size .
these were reviewed after the diagnosis was known , and in retrospect , although both kidneys appeared in the normal position , the right hemidiaphragm was not definitively identified .
preoperative mri images of the ectopic kidney were suggestive of a bochdalek hernia , demonstrating the bowel and the kidney within the thorax .
the complete hernia sac mimicked an eventration , or high - riding diaphragm on x - ray and intraoperatively .
the patient 's pulmonologist elected not to recommend diaphragmatic reconstruction . when the small , ectopic kidney was found , physicians discussed nephrectomy with the family .
normalization of the pressure , however , was a priority , especially in light of mild left ventricular hypertrophy on echocardiography .
bilateral renovascular hypertension is a contraindication to the use of an acei . some consider suspicion of renovascular hypertension as a general contraindication , even when unilateral .
a non - invasive , pharmacological destruction of the affected kidney was desired in this case , and suspicion of disease in the contralateral kidney was low . despite drug - related fatigue attributable to the acei , the family still hoped to find a tolerable pharmacologic strategy . an angiotensin receptor blocker and
a calcium channel blocker reduced pressures without adverse effects , but not below the 90th percentile .
pain in the post - operative period might have elevated her pressures , though her examination suggested that pain was well controlled .
levels of renin and aldosterone are not interpretable while receiving antihypertensives , and the pressures remained normal as doses were weaned .
removal of a unilateral poorly functioning kidney eliminates the need for medications in 75% of children and reduces the number of drugs required in almost all [ 10 , 11 ] . among those who benefit
, hypertension can continue for a few months , but the median time to normalization is 1 week .
even if , before surgery , the abnormal kidney provides more than 13% of total function , blood pressure and glomerular filtration remain excellent 516 years after removal .
few cases of such ectopic kidneys have been occasionally reported previously , but not with peri - arterial smooth muscle nodules .
this pathology has been described in arterioles of end - stage renal disease with marked hypertension . though this child 's blood pressures were higher than the 95th percentile for her age , they were much lower than the pressures typically associated with threats to vessel integrity .
we also found none of the pathologic changes to be associated with the obstruction of urine flow .
many reports of renovascular hypertension in children describe the restoration of renal blood flow using endovascular or percutaneous transluminal angioplasty .
compared nephrectomy with pharmacologic treatment in a unilateral multicystic dysplastic kidney ( mcdk ) , where spontaneous involution is almost universal . comparing 21 children who underwent nephrectomy with 20 who did not , outcomes were identical within 6 years .
but when the malformation is not mcdk , discrete arterial stenosis or part of a recognized syndrome , we have little information with which to predict the natural course . well - known limitations of pharmacologic management include non - adherence , medication side effects and medication failure . although 
pharmacologic nephrectomy is an attractive idea to parents and caregivers , after the review of the literature , we conclude that new techniques make nephrectomy the preferable solution for hypertension in the context of a malformed , poorly functioning kidney .
 standard initial assessment via ultrasound of a 4-year - old girl with hypertension revealed the absence of one kidney . instead of cross - sectional imaging of the retroperitoneal space , a functional ( nuclear ) study was performed . 
 this revealed a malformed kidney within the chest . 
 though systemic levels of renin and aldosterone were not elevated , removal of the malformed kidney normalized the blood pressure . 
 the presence of prominent smooth muscle nodules surrounding the arteries was seen in the malformed kidney . 
 initial attempts to avert surgery by pharmacologically reducing blood flow to the malformed kidney were unsuccessful . 
 the review of the literature offers little evidence to support such a strategy . 
Introduction
Case report
Discussion