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Pictorial essay Medical Ultrasonography 2011, Vol. 13, no. 1, 59-71 Abstract In children abdominal masses usually arises from the kidney and urinary tract. The reasons for patient’s presentation may be abdominal pain, palpable abdominal mass (usually discovered during the physical exam) and hematuria. Ultrasonography should be the first imaging investigation performed in children with an abdominal mass. It can be performed safely regardless of the clinical status of the patient, it is noninvasive and painless, requires no radiological contrast media and it is a relatively inexpensive. Ultrasonography is usually able to give an accurate localization of the lesion to a specific area or organ of the abdomen and provides good differentiation of solid from fluid or blood-filled masses. The purpose of this pictorial essay is to demonstrate the ultrasonographic features of the most frequently encountered reno-urinary masses in children. Keywords: renal masses, hydronephrosis, differential diagnosis, children, ultrasonography Rezumat Masele abdominale la copii îşi au adesea originea la nivelul rinichiului şi a tractului urinar. Pacienţii se prezintă cu dureri abdominale, masă palpabilă abdominală (adesea descoperită în timpul examenului clinic) sau hematurie. Examinarea ultra- sonografica ar trebui să fie prima metodă imagistică utilizată în evaluarea maselor abdominale la copii. Ecografia poate fi executată în siguranţă, indiferent de starea clinică a pacientului, este neinvazivă şi nedureroasă, nu necesită administrarea de substanţe de contrast şi este relativ ieftină. Ultrasonografia este cel mai adesea capabilă să determine cu acurateţe apartenţa la un organ a unei formaţiuni abdominale şi poate să diferenţieze cu succes masele solide de cele cu conţinut lichidian sau hemor- agic. Scopul acestui pictorial este de a exemplifica caracteristicile ultrasonografice ale celor mai frecvent întâlnite formaţiuni renourinare la copil. Cuvinte cheie: mase renale, hidronefroză, diagnostic diferenţial, copil, ultrasonografie The role of ultrasonography for diagnosis the renal masses in children. Pictorial essay Otilia Fufezan 1 , Carmen Asavoaie 2 , Cristina Blag 3 , Gheorghe Popa 3 1 3 rd Pediatric Hospital, Cluj-Napoca, 2 Radiology Department, Cluj-Napoca, Emergency County Hospital Cluj 2 Emergency County Hospital Cluj, 3 2 nd Pediatric Hospital, Cluj-Napoca Received 20.12.2011 Accepted 11.01.2011 Med Ultrason 2011, Vol. 13, No 1, 59-71 Address for correspondence: Dr. Otilia Fufezan 3 rd Pediatric Hospital 2-4 Campeni str, 400200 Cluj-Napoca, Romania E-mail: [email protected] The pictorial is structured in three major parts: solid masses, fluid-filled masses and masses of adjacent organs that may mimic a renal mass. The most common renal masses in each category will be presented with differen- tial diagnosis discussions. A. Solid Masses 1. Nephroblastoma or Wilms tumor The most frequent solid abdominal masses in chil- dren are nephroblastomas (Wilms’ tumors) and neurob- lastomas [1]. The nephroblastoma usually appears as a large renal mass that distorts the contour of the kidney and often has mass effect on surrounding structures. It has heter- ogenous echogenicity due hemorrhage, fat, necrosis or calcification content [2] and associates vascular invasion therefore examination of the inferior vena cava, even right atrium is crucial to detect tumor extension in order to orientate surgical approach [3] (fig 1, fig 2).

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Page 1: The role of ultrasonography for diagnosis the renal masses ... · 60 Otilia Fufezan et al The role of ultrasonography for diagnosis the renal masses in children The differential diagnosis

Pictorial essay Medical Ultrasonography2011, Vol. 13, no. 1, 59-71

AbstractIn children abdominal masses usually arises from the kidney and urinary tract. The reasons for patient’s presentation may

be abdominal pain, palpable abdominal mass (usually discovered during the physical exam) and hematuria. Ultrasonography should be the first imaging investigation performed in children with an abdominal mass. It can be performed safely regardless of the clinical status of the patient, it is noninvasive and painless, requires no radiological contrast media and it is a relatively inexpensive. Ultrasonography is usually able to give an accurate localization of the lesion to a specific area or organ of the abdomen and provides good differentiation of solid from fluid or blood-filled masses. The purpose of this pictorial essay is to demonstrate the ultrasonographic features of the most frequently encountered reno-urinary masses in children.

Keywords: renal masses, hydronephrosis, differential diagnosis, children, ultrasonography

RezumatMasele abdominale la copii îşi au adesea originea la nivelul rinichiului şi a tractului urinar. Pacienţii se prezintă cu dureri

abdominale, masă palpabilă abdominală (adesea descoperită în timpul examenului clinic) sau hematurie. Examinarea ultra-sonografica ar trebui să fie prima metodă imagistică utilizată în evaluarea maselor abdominale la copii. Ecografia poate fi executată în siguranţă, indiferent de starea clinică a pacientului, este neinvazivă şi nedureroasă, nu necesită administrarea de substanţe de contrast şi este relativ ieftină. Ultrasonografia este cel mai adesea capabilă să determine cu acurateţe apartenţa la un organ a unei formaţiuni abdominale şi poate să diferenţieze cu succes masele solide de cele cu conţinut lichidian sau hemor-agic. Scopul acestui pictorial este de a exemplifica caracteristicile ultrasonografice ale celor mai frecvent întâlnite formaţiuni renourinare la copil.

Cuvinte cheie: mase renale, hidronefroză, diagnostic diferenţial, copil, ultrasonografie

The role of ultrasonography for diagnosis the renal masses in children. Pictorial essay

Otilia Fufezan1, Carmen Asavoaie2, Cristina Blag3, Gheorghe Popa3

1 3rd Pediatric Hospital, Cluj-Napoca, 2 Radiology Department, Cluj-Napoca, Emergency County Hospital Cluj2 Emergency County Hospital Cluj, 3 2nd Pediatric Hospital, Cluj-Napoca

Received 20.12.2011 Accepted 11.01.2011 Med Ultrason 2011, Vol. 13, No 1, 59-71 Address for correspondence: Dr. Otilia Fufezan 3rd Pediatric Hospital 2-4 Campeni str, 400200 Cluj-Napoca, Romania E-mail: [email protected]

The pictorial is structured in three major parts: solid masses, fluid-filled masses and masses of adjacent organs that may mimic a renal mass. The most common renal masses in each category will be presented with differen-tial diagnosis discussions.

A. Solid Masses

1. Nephroblastoma or Wilms tumorThe most frequent solid abdominal masses in chil-

dren are nephroblastomas (Wilms’ tumors) and neurob-lastomas [1].

The nephroblastoma usually appears as a large renal mass that distorts the contour of the kidney and often has mass effect on surrounding structures. It has heter-ogenous echogenicity due hemorrhage, fat, necrosis or calcification content [2] and associates vascular invasion therefore examination of the inferior vena cava, even right atrium is crucial to detect tumor extension in order to orientate surgical approach [3] (fig 1, fig 2).

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60 Otilia Fufezan et al The role of ultrasonography for diagnosis the renal masses in children

The differential diagnosis includes firstly neuroblas-toma and than other, not as frequent, solid renal tumors like congenital mesoblastic nephroma, rhabdomyosar-coma or renal cell carcinoma.

Fig 1. Nephroblastoma in a 1 year and 8 months girl. a) US longitudinal view shows a large, round, well-circumscribed, heterogeneous mass, with few hypoechoic areas inside at the inferior pole of the left kidney. There are no visible calcifi-cations; b) transverse scan with color Doppler interrogation: there are no invasion signs within the left renal vein c) con-trast enhanced CT scan coronal reconstruction (Hiperdia Im-aging Diagnosis Center Cluj-Napoca collection) and d) axial sequence reveals the same features of the tumor: inhomogene-ous, well-circumscribed left renal mass with heterogeneous enhancement, left renal vein does not show signs of throm-bosis (Hiperdia Imaging Diagnosis Center Cluj-Napoca col-lection).

a)

c)

d)

b)

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61Medical Ultrasonography 2011; 13(1): 59-71

2. Bertin column hypertrophyHomogenous renal masses should be differentiated

in terms of their imaging features. Bertin column hyper-trophy is a normal variant, but may sometimes mimic a tumoral renal mass. The specific cortical pattern permits to establish a correct diagnosis (fig 3). Fig 4 and 5 show also homogenous renal masses but in these cases repre-sented by a malignant tumor and a posttraumatic renal hematoma.

Fig 2. Nephroblastoma in a 2 years old girl, after 1 month of chemotherapy a) the left upper pole of the kidney is occupied by a well-circumscribed, large, unhomogeneous mass with multiple hypoechoic areas, the lower pole of the kidney and the adrenal gland are visible; b) color Doppler interrogation in a longitudinal view shows no vessels in the tumor, renal vessels are displaced by the mass; c) transverse view reveals a perme-able left renal vein; d) three-dimensional ultrasound examina-tion allowed tumoral volume measurement (210 ml); e) postop-erative aspect confirmed the ultrasonographic findings (Dr. C. Ordeanu personal collection, with permission).

a)

c)

e)

b)

d)

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62 Otilia Fufezan et al The role of ultrasonography for diagnosis the renal masses in children

Fig 3. Bertin column hypertrophy. a) gray-scale longitudinal view of the right kidney: ovoid, isoechoic to the renal cortex “mass” that is flanked by two pyramids with protrusion into the renal pelvis; b) color Doppler examination did not reveal a pathological vascular pattern.

Fig 4. US longitudinal view of the right kidney in a 5 months old boy: ovoid, well circumscribed, homogenous and hypoe-choic mass that is disrupting the renal capsule. Histology re-vealed a nephroblastoma with anaplasia.

Fig 5. Longitudinal view of the left kidney shows an almost isoechoic, slightly inhomogeneous mid-renal mass with el-evation of the renal capsule represented by a post-traumatic hematoma.

B. Fluid-Filled Masses

Hydronephrosis secondary to ureteropelvic junction obstruction is the most common cause of unilateral renal mass in childhood [4], but other causes of hydronephro-sis are also frequently encountered like, the vesicoureter-al reflux or the megaureter.

Often these patients are diagnosed ultrasonographi-cally before birth. After birth the first imagining exami-nation is also ultrasonography as it is able to evaluate the

effect that these conditions have on the kidney (presence of dilatations, degree of hydronephrosis, parenchyma thickness, signs of infection). But further investigations, like voiding cystography or renal scintigraphy are neces-sary in order to establish the diagnosis [5].

1. Hydronephrosis due to ureteropelvic junction obstruction

In figure 6 it is presented the postnatal renal aspect in an antenatal detected bilateral hydronephrosis. The post-

a) b)

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63Medical Ultrasonography 2011; 13(1): 59-71

natal diagnosis in this 2 weeks old boy was: bilateral hy-dronephrosis, IInd degree on the right and IVth degree on the left. The ultrasonographic findings were suggestive

2. Hydronephrosis secondary to vesicoureteral refluxThe correlation between the severity of hydroneph-

rosis and the presence of vesicoureteral reflux is still un-clear. In the present it is accepted that only high degree vesicoureteral reflux is relevant for urinary tract infec-tions and renal scars [6]. Literature studies revealed that it is unlikely to find an abnormal voiding cystography in

Fig 6. Hydronephrosis due to ureteropelvic junction obstruction. a) US longitudinal view of the right kidney shows mild dilatation of the collecting system. The calices are dilated, but their concave shape is kept; longitudinal (b) and transverse (c) views of the left kidney reveal an important dilatation of renal pelvis and calices, the renal parenchyma thickness is reduced, the calices are flattened, the anteroposterior pelvis diameter is 28 mm. The content of the collecting system appears to be transonic. There is no ureteral dila-tation visible; d) longitudinal view of the left kidney 3 months after pyeloplasty shows improvement of the renal parenchyma and reduction of the collecting system dilatation.

a)

c)

b)

d)

for ureteropelvic junction obstruction. The postoperative outcome was favourable.

children with normal ultrasound examination [7]. Usu-ally, the ultrasound exam is abnormal in children with significant vesicoureteral reflux. Figure 7 presents a right hydronephrosis in a 2-weeks old boy with urinary col-lecting system dilatation detected before birth. The cause of hydronephrosis turned out to be the presence of vesi-coureteral reflux.

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64 Otilia Fufezan et al The role of ultrasonography for diagnosis the renal masses in children

3. Congenital megaureterToday most urologists apply a conservative man-

agement in vesicoureteral junction obstruction. Surgi-cal treatment is reserved just for symptomatic patients or in case of renal function deterioration [8]. In figure 8 we present the case of a 3 weeks old boy with abdomi-

Fig 7. Hydronephrosis secondary to vesicoureteral reflux. a) The right kidney (longitudinal view) presents pelvic and cal-iceal dilatation and there is a small cyst in the medial cortex; b) the transvers scan reveals fluid-debris level in the renal pel-vis; the aspect is characteristic for pyonephrosis; c) the voiding cystography (performed after infection healing) revealed the cause of hydronephrosis: severe right vesicoureteral reflux.

a)

c)

b)

nal distention and antenatal suspicion of an abdominal giant cyst. The ultrasonographic postnatal aspect was characteristic for a congenital megaureter. Further im-aging investigation were performed. The patient under-went surgery and the postoperative aspect was highly improved.

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65Medical Ultrasonography 2011; 13(1): 59-71

Fig 8. Congenital megaureter. a) coronal scan of the left flank showed a left kidney with a very thin parenchyma visible just in the middle area and lower pole, the adrenal gland is visible above the upper pole of the dilated urinary tract (s – spleen, ps – psoas muscle, cv – spine); b) longitudinal view in the left paramedian abdomen: from the kidney is emerging a very large transonic mass that is continued by a tubular, tortuous structure with a 3 cm diameter (giant ureter); c) transverse scan in the pelvis: the very enlarged ureter displaced urinary bladder on the right, urinary bladder has a normal wall thick-ness; d) voiding cystourethrography - anteroposterior projec-tion: there are no signs of vesicoureteral reflux, the bladder is displaced to the right, but has otherwise a normal appearance; e) postoperative ultrasonographic aspect: the left kidney has no dilations and a good parenchyma thickness of 8 mm.

a)

c)

b)

d)

e)

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66 Otilia Fufezan et al The role of ultrasonography for diagnosis the renal masses in children

4. Reno-urinary anomalies and urinary tract in-fection

Some literature data proposes an early assessment of antenatal detected hydronephrosis to reduce the risk of urinary tract infection [9]. This part presents a few cases with urinary tract infection suggested by the ultrasono-graphic aspect.

Figure 9 presents a 3 years old girl with prolonged fever and altered general clinical condition. Ultrasound exam permitted the diagnosis of ureteral duplication, ec-topic ureterocele and pyonephrosis. After antibiotic treat-ment and right nephrectomy the outcome was favourable.

A left antenatal detected hydronephrosis due to ure-teropelvic junction obstruction in a five days old boy is

Fig 9. a) coronal scan of the right upper quadrant: important dilatation of the collecting system and parenchyma atrophy, the content of the upper collecting system is hyperechoic sug-gesting the presence of pyonephrosis; b) longitudinal scan lower than previous image: there are two right ureters emerg-ing from the right kidney: the inferior right ureter appears di-lated and tortuous with an aspect suggestive for pus inside it, indicating pyoureter; the other ureter is also dilated but with an anechoic content. c) transverse view of the bladder: the superior right ureter (the anechoic one) protrudes into an ec-topic ureterocele that can be visualized close to the proximal urethra.

a) b)

showed in figure 10. The patient presented a good clini-cal status and ultrasonography was performed just for monitoring. The ultrasound findings allowed the detec-tion of an urinary tract infection.

Figure 11 presents also a urinary tract infection de-tected by ultrasound exam in a 1 month old boy with antenatal detected hydronephrosis due to vesicoureteral reflux.

5. Multicystic dysplastic kidneyUltrasonography allows a proper assessment and

monitoring of the multicystic dysplastic kidney. In figure 12 shows the role of three-dimensional ultrasonography in cysts volume monitoring.

c)

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67Medical Ultrasonography 2011; 13(1): 59-71

Fig 10. a) longitudinal view of left kidney and b) transverse view of the left kidney: the renal pelvis and calices show important dilatation with a pelvic diameter of 22 mm, the content of the collecting system is echogenic with floating spots inside, no dilatation of the left ureter visible.

Fig 11. a) oblique view ultrasound in the right upper quadrant: right kidney presents an echogenic parenchyma, moderate intermittent dilatation of the pelvis with thickening of the wall and mild caliceal dilatation; b) Longitudinal urinary bladder scan: right ureter is enlarged, urinary bladder and distal right ureter have an echogenic aspect suggestive for infection; c) transperineal scan revealed an ec-topic implantation of the distal right ureter; proximal urethra is not enlarged; d) voiding cystourethrography (UCGM) performed after urine sterilization confirmed ectopic implantation of the right ureter, near to the bladder neck and revealed right vesicoureteral reflux.

a)

a)

c)

b)

b)

d)

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68 Otilia Fufezan et al The role of ultrasonography for diagnosis the renal masses in children

C. Masses That May Mimic A Renal Mass

1. NeuroblastomaSince neuroblastoma and nephroblastoma are the

most frequent solid renal masses and because they arise in the same anatomic areas a differential diagnosis is al-ways necessary. Table I shows some of the most impor-tant diagnosis criteria [10].

Figure 13 presents the abdominal ultrasound of a 3 years old boy with abdominal pain and palpable abdomi-nal mass; the diagnosis was neuroblastoma. To show dif-ferent features in neuroblastoma and nephroblastoma, figure 13f presents a large mass in the left renal upper pole; the mass is well circumscribed, unhomogeneous, echoic, with transonic areas inside, the aspect is sugges-tive for a nephroblastoma in a 4 years old girl.

Fig 12. a) longitudinal scan of the right kidney: the right kidney contains many hypoechoic, non-communicating cysts of vari-able sizes and shapes. There are no parenchyma or vessels visible; b) the largest cyst has an initial volume of 5.2 ml calculated by three-dimensional ultrasound; c) ultrasonographic monitoring of the cyst size showed after one month that the cyst volume slightly incresed (6,9 ml); d) 3 months later the cyst was smaller (4 ml).

a) b)

c) d)

Table I. Major criteria in differential diagnosis between neph-roblastoma and neuroblastoma [10].Nephroblastoma (Wilms’ tumor) Neuroblastoma

Calcifications are uncommon Calcifications are common

Extension into renal vein and inferior vena cava

Vascular structures are encased, but not invaded by tumor

Patients usually 3-4 years old Patients usually under 2 years old

In most cases well circum-scribed Poorly marginated

Displaces surrounding structure without insinuating between them

Elevates aorta in relation to the spine

“Claw” sign with kidney Renal invasion

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69Medical Ultrasonography 2011; 13(1): 59-71

Fig 13. Neuroblastoma in a 3 years old boy: a) US longitudinal view of the left kidney: there is large, poorly circumscribed, hypoe-choic, inhomogeneous mass visible in the upper part of the left kidney, the renal capsule is disrupted and the kidney lost its shape; b) transverse section at the pancreas level reveals vessels integrated in the tumor; the aorta is elevated in relation to the spine (ao – aorta; vci – inferior vena cava); c) transverse Doppler examination of the celiac axis shows that vascular structures are encased in the tumor; d) and e) contrast enhanced computed tomography confirmed the ultrasonographic diagnosis: the aorta, the celiac axis, superior me-senteric artery and both renal arteries are encased in the tumor (Hiperdia Imaging Cluj-Napoca Center collection); f) longitudinal scan of the right kidney in a girl with nephroblastoma: the tumor is visible in the upper pole of the kidney, the lower pole is visualized and caliceal dilatations are present in it, the mass has no calcifications; adrenal structure is visible cranial to the tumor.

a)

c)

e)

b)

d)

f)

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70 Otilia Fufezan et al The role of ultrasonography for diagnosis the renal masses in children

2. Adrenal hemorrhageAdrenal hemorrhage is characterized by a hypoechoic

or anechoic well limited mass above the upper pole of the kidney. This pathology resolves spontaneously by calci-fication. In figure 14 is presented a 2 weeks old boy with

Fig 14. US longitudinal view of the left kidney: a) there is an oval, well circumscribed, inhomogeneous hypoechoic mass on the upper pole of the kidney, the mass has a thick wall, an echo-genic septum inside, but no vascularization, the ultrasonograph-ic aspect is suggestive for a left adrenal hemorrhage. b) after 2 months the mass has significantly reduced it’s size (2.3 cm) and is almost entirely hyperechoic; c) after 3 months: in this stage the adrenal mass is small (0.7 cm) and presents a hyperechoic calcified aspect.

birth trauma and a large hypoechoic mass on the upper left kidney pole. Ultrasonographic features permitted the diagnosis of adrenal hemorrhage. After 3 months calcifi-cation in the adrenal gland was found.

a)

Conclusions

Modern ultrasonography is an extremely valuable technique in the detection and evaluation of renal mass-es. Awareness of the advantages and limitations of ul-trasound is essential both for an accurate diagnosis and avoiding other unnecessary imaging investigations.

First of all ultrasonography is able to distinguish solid from fluid masses with high accuracy. It offers informa-

tion about localization, size, shape, echogenicity, effect of the lesion on the renal parenchyma, collecting system or the surrounding structures and appreciation of vascu-larization and lymph nodes.

When further investigations are necessary the differ-ential diagnosis of these lesions usually benefits from the contribution of contrast enhanced CT, especially in the case of solid masses, and of voiding cystography or renal scintigraphy for some of the fluid-filled masses.

b)

c)

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