9%20ECOGRAFIA%20ABDOMINAL%20COMO%20CUANDO%20DONDE

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ABDOMINAL ULTRASOUND
LT
LT
A
B
Figure 9.11 (A) The dilated collecting system of this kidney is filled with a large, rounded fungal ball of candidiasis
infection. (B) The fungus ball is seen to disintegrate, emptying into the renal pelvis.
The tumours are large at presentation, presenting
with a palpable abdominal mass, and, less frequently,
pain, haematuria and fever. About 5% of these
tumours are bilateral. 20 The prognosis when unilateral
is generally good.
The ultrasound appearances are of a relatively
well-defined heterogeneous mass, predominantly
solid but frequently with some necrotic or haemorrhagic
areas, often almost completely replacing
the kidney (Fig. 9.12). Small focal areas of calcification
are seen very occasionally. A search should
be made for tumour invasion of the renal vein and
IVC which occurs in up to 10% of cases. Tumour
invasion may extend into the right atrium.
Occasionally a large, right-sided Wilms’ tumour
may compress the IVC but not invade it; colour or
power Doppler may be useful in the difficult distinction
between compression and invasion on
ultrasound. Ultrasound also identifies associated
lymphadenopathy, particularly in the para-aortic
and paracaval regions, and metastatic liver disease.
In a small percentage of cases, tumour may also
be found in the contralateral kidney. This is usually
much smaller than the mass on the presenting side
and may be acoustically subtle. Up to 7% of contralateral
tumours are missed on preoperative
imaging due to their small size and the operator
must be alert to the possibility of bilateral disease. 20
Occasionally a Wilms’ tumour may be found to
be predominantly cystic, having the appearances of
a large, multiloculated cystic mass. The main differential
diagnosis would be of a mesonephric blastoma
occurring during the first year of life and
histology is required to establish the diagnosis.
In most cases, an ultrasound and chest radiograph
are sufficient to diagnose correctly Wilms’
tumour but CT of the chest and abdomen is generally
used for staging, and to exclude metastatic
disease in the chest and liver. 21 Percutaneous
biopsy for confirmation of histological type is generally
performed. CT or MRI is more sensitive
than ultrasound scanning in demonstrating small
tumours in the contralateral kidney.
Xanthogranulomatous pyelonephritis
Xanthogranulomatous pyelonephritis results from
chronic infection in an obstructed kidney and children
present with a history of general malaise, lowgrade
fever and flank pain and may be found to be
anaemic. The finding of a palpable abdominal mass
on examination often leads to an early diagnosis of
a possible Wilms’ tumour. On sonography the kidney
is diffusely enlarged, with loss of the normal
corticomedullary differentiation. The presence of
calyceal dilatation with debris and calculi in the collecting
system and confirmation of urinary infection
in addition to the generalized involvement of
the kidney helps to differentiate this condition
from Wilms’ tumour (Fig. 9.12B). Occasionally