topic 10 - paediatric urinary tract and adrenals Flashcards
(97 cards)
1
Q
Why is it important to recognise persistent fetal lobulation?
A
should not be confused with renal scarring and may persist into adulthood
2
Q
How can you tell the difference between persistent fetal lobulation and renal scarring?
A
• Fetal lobulation is distinguished from scarring by the presence of a smooth renal contour, regular spacing, and absence of calyceal blunting.
• The indentations spare the renal pyramids, unlike scarring, in which the renal parenchyma overlying the pyramids appears thinned.
always occurs between medullary pyramids
3
Q
What is a junctional renal parenchymal defect?
A
• The renal junctional parenchymal defect (interrenicular septum or fissure) is the most prominent of these grooves
should not be confused with scarring
• extending from the hilum to the cortex
• it is caused by perirenal fat adherent to the renal capsule along a cleft on the renal surface.
• It is frequently seen in the anterosuperior aspect of the kidney
4
Q
In what ways does the infantile kidney differ from the adult?
A
- The central echo complex is much less prominent due to less peripelvic
- Renal cortical echogenicity is increased in the premature infant kidney compared with the liver and spleen.
- term infant kidney is often the same as the echogenicity of the adjacent normal liver
- The medullary pyramids are relatively larger and tend to appear more prominent (more hypoechoic).
- The corticomedullary differentiation is greater
5
Q
What are some causes of mild hydronephrosis is children
A
- Mild degrees of distention can be seen in normal children, particularly after recent high intake of fluids or diuretics.
- A normally distended urinary bladder can also cause functional ureteral obstruction and mild distention of the renal collecting systems.
6
Q
What is the sonographic appearance of the paediatric adrenal gland?
A
- attains an adult echo pattern by one year of age.
- 0-2 months There is a ‘triple stripe’ appearance, with the hypoechoic outer layers representing mostly cortex and the echogenic middle layer mostly consisting of medulla.
- It appears large and is easy to identify because there is little peri-renal fat.
- By the end of the first 12 months, the adrenal gland has become much more difficult to see.
- It will be located in the suprarenal region and has a V, Y or Z shape.
7
Q
What is the key sign of obstructive nephropathy?
A
splitting of the calyces and a corresponding increase in size of the renal pelvis.
8
Q
What measurements indicate obstruction?
A
A renal pelvis AP diameter of 10 mm or greater in the transverse plane is considered significant, but any calyceal dilatation is also significant.
9
Q
How should a linear transducer be used to image a paediatric kidney?
A
- magnifica¬tion of selected parts of each kidney is essential to depict smaller structures in the parenchyma to best advantage.
- Limiting the field of view to the half of the kidney closest to the transducer and focused evaluation of only one or two pyramids and the surrounding cortex often helps resolve areas of interest in the pyramids better
10
Q
Why is it important to be familiar with the neonatal kidney appearance?
A
• To those unfamiliar with this normal neonatal appearance, the relatively large, normal, hypoechoic pyramids may be misinterpreted as dilated calices or renal cystic disease and the relatively thinner hyperechoic cortex may be misinterpreted as cortical scarring or even ischemic changes.
11
Q
What can increase the thickness of the bladder wall?
A
inflammation or muscular hypertrophy.
12
Q
When are post void bladder views helpful?
A
may be helpful in patients with a neurogenic bladder or dilated upper collecting system, because a distended bladder may cause increased dilation but improve after voiding.
13
Q
How can you reduce patient motion artefact?
A
• High frame rates and low persistence are
14
Q
Which measurements are important for the paediatric kidney?
A
Obtain the maximum longitudinal length of both kidneys and plot the measurements on a paediatric renal length chart. Previous measurements should be included on the chart for comparison. The transverse AP diameter of the renal pelvis of each kidney should be measured.
15
Q
What are horseshoe kidneys ore disposed to and why?
A
Abnormal rotation of renal pelves often results in ureteropelvic junction (UPJ) obstruction; the horseshoe kidney is thus predisposed to infection and stone formation.
16
Q
How would you differentiate horseshoe kidney from other major congenital variants?
A
in horse shoe kidney the isthmus of renal parenchyma is crossing the spine.
Consider the other variants:
Renal agenisis: There is a unilateral kidney only.
Renal Ectopia
Simple: In this case the kidneys are clearly not in the pelvis.
Crossed: In this case, the kidneys are on opposite sides of the abdomen.
Horseshoe kidney is very common occuring in 1 in 400 people. The two lower poles are connected by parenchyma or fibrous tissue. It highlights the importance of visualising the full dimension of the kidney otherwise this will be missed.
17
Q
What are the most common developmental obstruction types?
A
- PUJ, vesico-ureteric junction (VUJ) obstruction
- posterior urethral valves (PUV, only in boys)
- complete ureteral duplication associated with a ureterocele, also known as a obstructed duplex kidney
18
Q
What is the most common reason for paediatric renal ultrasound referral?
A
Urinary tract infection
19
Q
What is the ai of paediatric renal ultrasound in the setting of 1st UTI?
A
- It is to check for a developmental structural anomaly, such as a pelvi-ureteric junction obstruction (PUJ).
- Developmental obstruction can go undetected up to adult life, especially if it is unilateral
- if renal function of the obstructed kidney is to be preserved, it must be detected and repaired.
- Children that have structural anomalies are at higher risk of contracting UTIs. These can affect the overall renal function
20
Q
What is a non ultrasound way to assess the kidney obstruction?
A
, the nuclear medicine DTPA or Mag 3 are used to assess the point of obstruction.
21
Q
What is important to consider when following up a previously obstructed kidney?
A
, the pelvicalyceal system can remain dilated after the obstruction has been removed, and care must be taken not to diagnose hydronephrosis (implying re-obstruction) when, in fact, it is simply a baggy, over stretched system that is functioning normally
22
Q
What is UPJO and what can cause it?
A
- most common cause of significant prenatal hydronephrosis
- usually results from a functional stricture at the ureteropelvic junction (UPJ)
- or a crossing lower-pole renal vessel.
- There is also an associated increased incidence of congenital anomalies of the contralateral kidney.
23
Q
How does UPJO ureteropelvic junction obstruction appear on ultrasound?
A
- diagnosis of hydronephrosis is based on the presence of a dilated renal pelvis and caliectasis.
- A variable amount of renal parenchymal tissue can be visualized.
- The ureter is normal in size and is not usually visualized by ultrasound
24
Q
What is UVJO and what causes it?
A
ureterovesicular junction obstruction
• result of narrowing and aperistalsis of the distal ureter
• or an ectopic insertion.
- can also be obstructed by an intraluminal abnormality, such as a stone, blood clot, or fungus ball.
• There is a variable degree of dilation of the intrarenal collecting system and of the ureter proximal to the narrowing.
25
What causes primary megaureter?
the juxtavesicular ureter may be devoid of ganglion cells or may demonstrate muscular hypoplasia and/or mural fibrosis
• The submucosal tunnel and ureteral orifice are normal.
26
How does Ureterovesicular junction obstruction appear on ultrasound?
• typically shows hydronephrosis and hydroureter
• with a narrow segment of the distal ureter behind the bladder
• Doppler sonography may show a diminished or abnormal ureteral jet on the side of obstruction
- can also be obstructed anywhere along its course by extrinsic compression from a mass, such as a lymphoma or abscess.
27
How is ureterovesicular junction obstruction imaged beyond ultrasound to confirm diagnosis?
• MAG3 diuretic renography is typically used to clarify whether the dilation is caused by obstruction.
28
What is a frequent cause of bilateral hydronephrosis?
obstruction at the level of the bladder or bladder outlet.
29
What are the possible causes of bladder obstruction?
posterior urethral valves (PUVs)
• Patients with spinal dysraphism and hyperreflexive detrusor muscle activity will have a functional obstruction due to a neurogenic bladder
• A pelvic mass that obstructs the bladder outlet, such as rhabdomyosarcoma, or less commonly, a fibroepithelial polyp, can also be associated with bilateral hydronephrosis and hydroureter
30
How can posterior uretheral valves appear on ultrasound?
an irregular, thick-walled bladder.
• PUV can occasionally be diagnosed by ultrasound, with demonstration of a dilated posterior urethra.
.
31
How are posterior uretheral valves diagnosed?
occasionally be diagnosed by ultrasound
| However, VCUG( voiding cystourethrogram) should be performed for optimal visualization of the valves
32
How can a neurogenic bladder look?
thick-walled, trabeculated bladder
33
What further testing should be done when a patient presents with bilateral renal hydronephrosis?
* In a child with hydronephrosis detected by ultrasound, the bladder size and contractility and the urethra should be further evaluated with VCUG.
* VUR can be diagnosed and may be the cause of the UTD.
34
How are patient with VUR treated and how will it appear on ultrasound?
* Patients with reflux are often treated endoscopically with a submucosal, subureteric injection of a bulking agent.
* Follow-up sonography of the bladder will depict the implants, which over time may undergo changes in size and shape as well as calcification
* nonvisualization of the implant or a multilobed contour is associated with persistent reflux.
35
How can renal dysplasia and cyst formation occur in the fetus?
• if the urinary obstruction starts during the first half of gestation
36
What are some causes of unilateral renal dysplasia?
UPJ obstruction or ureterovesical junction (UVJ) obstruction.
37
What are some causes of bilateral renal dysplasia?
severe bladder outlet obstruction, usually due to urethral atresia or posterior urethral valves
38
How can the severity of renal dysplasia be explained?
• The severity of renal dysplasia is related to the timing and severity of obstruction to urine flow
39
What are some signs of renal dysplasia in the fetus?
identification of cortical cysts is indicative of renal dysplasia (i.e., irreversible renal damage)
• may also demonstrate cortical thinning and increased echogenicity relative to the surrounding fetal structures, with loss of corticomedullary differentiation
• increased cortical echogenicity is not a specific finding
• diagnosis of renal dysplasia cannot be made on the basis of increased parenchymal echogenicity alone.
40
Why can you not accurately predict the absence of renal dysplasia in the fetus?
• not all dysplastic kidneys have sonographically visible cysts or increased cortical echogenicity, so one cannot accurately predict the absence of renal dysplasia
41
How can you differentiate MCDK and obstructive cystic renal dysplasia ?
• may be difficult
• especially in the absence of hydronephrosis.
• In obstructive cystic renal dysplasia;
o recognizable parenchyma surrounds the relatively small cysts
o most often occurs with urethral obstruction - sonographic evidence of urethral obstruction is helpful
o renal dysplasia from lower UT obstruction frequently involves both kidneys
• MCDK;
o no normal renal parenchyma can be identified between cysts
o cysts can be of varying size and can be quite large in suggesting the diagnosis
o bilateral MCDK occurs in only 19% to 24% of cases
42
What are the sonographic features of autosomal recessive polycystic kidney disease (ARPKD)?
Renal sonographic features of ARPKD include a lack of corticomedullary differentiation and massively enlarged echogenic kidneys. Occasionally, macroscopic cysts will be noted.
43
Name the renal pathologic entities that result in the accumulation of multiple intrarenal fluid collections (cysts)
ARPKD (inherited)
ADPKD (inherited)
Medullary sponge kidney (bilateral and acquired)
Obstructive renal dysplasia (bilateral or unilateral and acquired)
Multicystic dysplastic kidney (usually unilateral and acquired)
44
What is the most common form of renal cystic disease in childhood?
Multi cystic dysplastic kidney
| also one of the most common abdominal masses in the neonate
45
How does multicystic dysplastic kidney appear on ultrasound?
• renal pelvis and ureter are usually atretic and not visible
• kidney is replaced by multiple cysts of varying sizes.
• Between the cysts is a dense stroma
• usually no normal renal parenchyma.
• Kidneys affected with multicystic dysplasia are almost always nonfunctional
• Assessment of the contralateral kidney is very important. In 19% to 24% of cases, multicystic renal dysplasia is bilateral.
absent or very small renal artery
46
How can MCDK and hydronephrosis be differentiated?
• MCDK with a large central cyst and small peripheral cysts can mimic hydronephrosis from ureteropelvic junction (UPJ) obstruction
• In hydronephrosis the dilated calyces are of uniform size and anatomically aligned and communicate with the dilated renal pelvis.
The kidney usually maintains the reniform contour, with renal parenchyma present peripherally.
47
What kidney appearance is indicative of ARPKD?
* the finding of bilateral, very large (>4 standard deviations), diffusely hyperechoic kidneys with poor corticomedullary differentiation, with or without visible cysts, is most likely due to ARPKD
* Another typical pattern is very large kidneys with a peripheral hypoechoic rim surrounding the centrally increased echogenicity or hyperechoic pyramids (reversed corticomedullary differentiation)
48
How can ADPKD appear in paediatrics?
* characterized by cyst formation in the kidneys and liver
* Cysts may also be present in the pancreas and spleen, and the disorder is associated with CNS aneurysms
* In rare cases, ADPKD can manifest during the fetal or neonatal period with symmetrical moderately enlarged hyperechoic kidneys, within which small cysts (<7 mm) may be identified
49
What is essential in the diagnosis of ADPKD?
family history
50
How can you definitively diagnose MCDK vs obstructive renal dysplasia?
definitive diagnosis belongs to nuclear medicine, which can assess function with a DTPA or Mag 3 scan
. Nuclear medicine DTPA or a Mag 3 scan can make the definitive diagnosis because they assess function.
A true MCDK will show no uptake of radionuclide.
51
How does MCKD appear on ultrasound?
Anechoic cysts of varying size which show no communication.
The largest cyst is not usually in the location of the renal pelvis.
The cysts are held together by dysplastic renal tissue that is usually homogenous and may or may not be of the same echogenicity as normal renal tissue (usually not).
Sometimes only one large cyst and a smaller daughter cyst are seen.
Sometimes a hydronephrotic form is seen as small cysts surrounding a larger one
52
Describe the sonographic findings of an obstructed duplex system.
In the acute stage the upper moiety displays -
- parenchymal thinning
- variable degree of hydroureteronephrosis that can contain echogenic, fine grained debris, which is pus, known as pyoureteronephrosis.
- If the ureter is severely dilated, it can follow a tortuous path to the bladder.
- The distal ureter of this upper moiety can be stenotic or insert into a ureterocele.
- The ureterocele appears as a rounded, thin walled, anechoic cyst-like structure at the bladder base.
In the chronic, longstanding stage
- the upper moiety can display homogenous, dysplastic renal tissue with a loss of corticomedullary differentiation and small cysts with a small ureter which may or may not be dilated.
53
what further imaging is required and why in an obstructed duplex system?
A nuclear medicine DTPA or a Mag 3 scan
- will ascertain if obstruction of the upper moiety is occurring at the ureterocoele in the acute stage and in the chronic stage
- will assess whether there is any function in the upper moiety.
- In the lower moiety An MCU can determine the presence of reflux and a nuclear medicine DMSA scan can assess the cortex for scarring and a DTPA or Mag 3 can assess function.
- In the lower moiety, due to its ectopic insertion in the bladder base, it predisposes it to reflux.
- The lower moiety can show some dilatation due to reflux and, if severe, the ureter can also be dilated.
54
An 8 month old premature baby who is failing to thrive presents to the department for an abdominal ultrasound. Both kidneys are seen to contain small simple cysts which are predominately parenchymal. Discuss the appearances and your primary differential diagnoses. Reflect on the other differential diagnoses and discuss why you deemed these less likely.
Both kidneys are seen to contain small cysts which are predominately parenchymal. These don't appear to have the complex nature of recessive autosomal polycystic disease.or of glomerulocystic disease. The appearances autosomal dominant polycystic disease and in this context may be an incidental finding.
55
What are we especially interested in when assessing for a current or previous renal infection?
Renal size, cortex, contour, pelvis and bladder wall
56
What is assessed when looking at renal size?
assessed for global or focal enlargement
57
What is assessed when looking at the renal cortex?
Look particularly for a diffuse loss of corticomedullary differentiation, or focally for an echogenic area which may develop into an abscess.
58
What is assessed when looking at the renal contour?
Look for loss of cortex that indicates scarring of the kidney, particularly in the polar regions.
59
What is assessed when looking at the renal pelvis?
Look for thickening of the walls of the renal pelvis and ureter if prominent
60
What is assessed when looking at the bladder wall?
Cystitis is seen sonographically as bladder wall thickening and possibly mobile debris. The bladder must be about two thirds full to assess for bladder wall thickness. Otherwise an under-filled bladder can lead to false positives
61
Why are renal lengths plotted on a growth chart?
Acute pyelonephritis can cause long-term renal parenchymal damage by scarring the kidney/s. The scarred area becomes non-functional
62
How is acute infection diagnosed clinically?
patients with a sudden onset of fever, flank pain, costovertebral angle tenderness, and microscopic evidence of urinary infection
63
What are the most common causes of renal infection?
* VUR is clearly a risk factor for the development of acute pyelonephritis
* which often starts as an ascending infection from the bladder
* can also occur by hematogenous spread.
64
What are some ultrasound appearances of renal infection?
* may be swelling of the infected kidney
* altered renal parenchymal echogenicity from edema causing triangular areas of increased echogenicity
* or rounded hypoechoic zones.
* Focal pyelonephritis can appear as a localized mass with abnormal echogenicity compared with the remainder of the kidney and loss of corticomedullary differentiation
* There may be thickening of the wall of the renal pelvis and ureter, also caused by edema and inflammation
* Sequential examinations of these focal infected areas will typically demonstrate a rapid change, with resolution of the mass in response to antibiotic therapy.
* Another potential complication of acute pyelonephritis that requires drainage is pyonephrosis, which appears on sonography as echogenic material filling a dilated collecting system
65
Why might a kidney appear smaller on a follow up renal scan after infection?
because the swelling from the infection has gone.
66
What is indicative of no renal growth?
* At the first 6 month examination, a baseline (for example, both kidneys along the 65th percentile) is set
* When they return in another six months the measurements are compared to this original percentile measurement
* A difference of 10 percent or greater between right and left renal sizes is indicative of no growth in the smaller kidney (which is why measuring the kidney accurately is so important) and the child requires further management from the paediatric urologist.
67
How does chronic infection appear on ultrasound?
* results in a small, scarred kidney, indicative of end-stage renal disease.
* The kidney is usually irregular in outline because of focal parenchymal loss.
* The renal cortex is typically more echogenic than the adjacent hepatic or splenic parenchyma
* there may be decreased corticomedullary differentiation
* These findings are not specific and can also be seen in children with chronic glomerulonephritis, renal dysplasia, hypertension, or renal ischemia.
68
How does neonatal candidiasis occur?
* t usually infects immunocompromised patients
| * particularly neonates with indwelling catheters receiving broad-spectrum antibiotics.
69
How do patients with candidiasis present?
• neonates may have anuria, oliguria, a flank mass, or hypertension.
70
How can candidiasis appear on ultrasound?
may show diffuse enlargement of the kidney, with loss of normal architecture and increased parenchymal echogenicity
• Fungus ball formation due to mycelial clumping may occur in the collecting system, resulting in echogenic masses and hydronephrosis secondary to obstruction
71
What is the role of ultrasound in imaging the bladder?
• The role of ultrasound of the bladder is limited in most pathological contexts.
• The common bladder abnormality is secondary to a UTI and will present as cystitis.
• The bladder in this instance is thick-walled and contains fine grain–like mobile echogenic debris.
Children with spina bifida have trabeculated or neurogenic bladder and can develop bladder calculi due to urine stasis
72
How can the bladder wall appear in cases of cystitis?
* The bladder wall becomes thickened and irregular, with hypervascularity identified with color and power Doppler imaging.
* Echogenic debris or blood clot may be seen in the bladder lumen
* Rarely, an inflammatory pseudotumor may result, with visualization of a bladder mass
73
A nine month old baby presents with a UTI and is diagnosed with acute pyelonephritis. Why are we doing the ultrasound?
* A renal ultrasound is performed to check for a structural anomaly.
* Children with structural anomalies are at increased risk for UTIs.
* Serial ultrasounds should be done to check for ongoing renal growth
74
Pt 2 A nine month old baby presents with a UTI and is diagnosed with acute pyelonephritis. The baby goes on to have an MCU and it shows reflux. Should we perform serial ultrasounds? Why or why not? What further imaging should we do and why?
* Shortly after finishing antibiotic therapy, a nuclear medicine DMSA scan may be done to assess for cortical scarring and inflammatory change
* as well as an ultrasound to measure renal lengths when the patient is well.
* About three to six months later, a follow up ultrasound should be done to check for ongoing renal growth.
* If growth is not evident, a nuclear medicine DTPA or Mag 3 scan may be done to assess whether renal function has dropped off.
75
What is a Wilms tumour?
* solid tumour that originates in the kidney.
* usually occurs in children under age 15
* peak incidence 3-4 years
* most common abdominal tumour and can be bilateral in 10 percent of cases.
* When the tumor is large, it may be difficult to differentiate from neuroblastoma, which frequently arises from the adrenal gland
76
Why is the method of spread in Wilms tumour important to know?
so a renal ultrasound can be extended to cover the abdomen, searching for vascular, hepatic, lymphatic or direct invasion.
77
What is the method of spread for a Wilms tumour?
Wilms tumor spreads via direct extension into the renal sinus and peripelvic soft tissues, the lymph nodes in the renal hilum, and the paraaortic regions. Because extension is possible into the renal vein, inferior vena cava, right atrium, and liver, these areas should also be examined for the presence of tumor
78
What is the typical appearance of a Wilms tumour?
* Large solid mass distorting the renal sinus, pyramids, cortex, and contour of the kidney as depicted with sonography.
* usually quite hyperechoic and homogeneous
* there may be hypoechoic areas that represent hemorrhage and necrosis.
* Decreased blood flow compared with the adjacent renal parenchyma
79
How should you examine a suspected Wilms tumour?
* document the size
* outline
* position
* internal architecture
* vascularity
* shape of the mass.
* Try to determine if the mass is emanating from the kidney
* check for spread in the renal vein, IVC, liver and the other kidney.
* Also, assess the para-aortic region and spleen.
* Histology is required to confirm the diagnosis of Wilm's tumour.
80
What is the typical appearance of neuroblastoma?
* suprarenal mass, pushes kidney inferior and posterior
* heterogenous, with hypoechoic area within representing necrosis and echogenic foci with posterior shadowing representing calcium
* ill-defined and nonencapsulated, sonographically difficult to define edges
* mass crosses midline, encasing the great vessels
* hepatic metastases common, seen as target lesions, echogenic centres with hypoechoic rim
81
What are the typical appearances of a Wilms tumour?
* mass invades the kidney
* well-defined and encapsulated, hypoechoic or hyperechoic rim, representing renal tissue/tumour interface
* usually homogenous and echogenic
* echogenic debris which is thrombus in renal vein and IVC
* does not cross midline, displaces midline vessels, that is, pushes great vessels aside
82
Why is defintive diagnosis of Wilms vs Neuroblastoma achieved with histology?
As atypical appearances of both can appear similar to the typical appearances of the other
Wilm’s tumour – atypical sonographic appearances:
• exophytic, that is, growing out and away from the kidney
• heterogenous centre due to necrosis and haemorrhage
• calcific foci
Neuroblastoma – atypical sonographic appearances:
• homogenous, well-defined suprarenal mass, about the same echotexture as kidney
• aggressive tumours invade the kidney
83
What is the method of spread for wilms tumour?
```
Wilm’s tumour – method of spread:
• by direct extension into capsule
• metastases to liver
• vascular invasion by tumour thrombus in renal vein and IVC
• enlarged lymph nodes
• can be bilateral
```
84
What is the method of spread for neuroblastoma?
Neuroblastoma – method of spread:
• enlarged lymph nodes indicate spread
• metastases to liver can be target lesions or diffuse infiltration, such that liver has a course texture and is enlarged
• skeletal metastases
• bone marrow metastases
• skin metastases appearing as lesions on the skin.
85
How is the adrenal gland measured?
* From the transverse images of the gland, AP and transverse dimensions are measured.
* From the longitudinal images, the cephalocaudal length is measured from the apex to the midpoint of the base of the gland.
86
What does the lying down adrenal sign indicate?
• If there is renal agenesis or ectopia, the neonatal gland will appear flattened and “lying down” along the psoas muscle on longitudinal sonograms
87
How does haemorrhage of the adrenal gland occur?
* Haemorrhage can occur during the birth process due to stress.
* Its sonographic differential is neuroblastomas so serial scans are done over two weeks to assess for liquefaction and regression.
88
How does adrenal haemorrhage appear on ultrasound?
* suprarenal mass of variable echogenicity, depending on the age of the bleed.
* Acute haemorrhage usually appears echogenic or isoechoic to the normal gland, without internal vascularity on color Doppler imaging.
* Over several weeks, the haemorrhage becomes anechoic, reflecting blood clot lysis and liquefaction
* gradually decreases in size and may result in adrenal calcification.
* Differentiation from a neonatal neuroblastoma is important.
* Follow-up demonstrating a progressive decrease in size and eventual resolution confirms the diagnosis of an adrenal haemorrhage.
89
What is congenital adrenal hyperplasia?
* an inherited form of adrenal insufficiency
* caused by autosomal recessive mutation of genes
* There is impaired synthesis of cortisol by the adrenal cortex
* This results in an excessive accumulation of androgenic precursors and adrenal gland enlargement
90
How does congenital adrenal hyperplasia present clinically?
• Infants may have salt-wasting, virilization of the external genitalia in girls, and precocious puberty in boys.
91
How is adrenal size related to CAH?
* CAH causes bilateral adrenal gland enlargement
* may be asymmetrical.
* thicker than 4 mm is considered enlarged
* adrenal gland enlargement alone is not sensitive or specific for the diagnosis of CAH.
* A normal-sized adrenal gland does not exclude the diagnosis of CAH
* and some healthy babies have adrenal glands in the size range typical of CAH
92
What are some specific ultrasound features to make the detection of CAH more sensitive?
* cerebriform appearance of the gland and stippled echoes, or diffusely increased central glandular echogenicity rather than the normal central echogenic stripe.
* Although the external genitalia are masculinized, the internal female genitalia are present.
* Testicular adrenal rest tumors are very common, particularly in postpubertal boys with poorly controlled congenital adrenal hyperplasia.
93
How do testicular adrenal rest tumours appear on ultrasound?
* These tumors are small, generally multiple, and often bilateral.
* The involved testis may be enlarged, but its contour is not distorted.
* The masses are eccentric and commonly surround the mediastinum testis
94
What is a neuroblastoma and how do patients present?
* second most common paediatric abdominal tumour.
* arises from neural crest tissue
* Patients tend to present at about two years of age with an abdominal mass.
* Two-thirds of the time, neuroblastoma develops in the abdomen, with approximately two-thirds of the tumors arising from the adrenal gland.
* The remainder may develop anywhere along the sympathetic nerve chain
* The mass is easily palpable and hence, quite large, making it difficult to determine if the tumour is intra-renal (and therefore most likely a Wilm's) or extra-renal and most likely a neuroblastoma.
95
How does a neuroblastoma appear on ultrasound?
* The para-aortic region must be checked carefully for lymphadenopathy and the liver for metastases.
* Histology is required to confirm the diagnosis of neuroblastoma.
* Heterogeneous in echotexture, with irregular, hyperechoic areas caused by calcification.
* Its margins tend to be poorly defined.
* Extension of tumor around the aorta and celiac and superior mesenteric arteries helps to distinguish neuroblastoma from Wilms tumor, which is usually well defined and relatively homogeneous in echotexture
96
What is a pheochromocytoma and how does it present?
* can be inherited.
* They are rare, tend to be bilateral, multiple and extra-adrenal in origin.
* They occur most commonly along the paravertebral sympathetic chain and hence ultrasound is not the imaging method of choice.
* Signs and symptoms suggestive of pheochromocytoma include sustained hypertension, paroxysmal episodes of headache, palpitations and diaphoresis, pallor, orthostatic hypotension and syncope, tremor, and anxiety.
97
How does pheochromocytoma appear on ultrasound?
* a pheochromocytoma will appear as a solid, highly vascular, round or oval mass of variable echogenicity.
* Masses generally range from 2 to 5 cm in diameter at presentation, although they may exceed 10 cm.
* Larger lesions tend to be heterogeneous as a result of hemorrhage, necrosis, and/or calcification
