Diagnostic ultrasound ( PDFDrive )

1820 PART V Pediatric Sonography
A
B
FIG. 52.64 Contrast-Enhanced Ultrasound (CEUS) of Wilms Tumor. (A) Longitudinal gray-scale image of right kidney reveals a bulbous
appearance of the upper pole (arrows) without a clearly-deined mass. L, Liver. (B) Longitudinal CEUS image better deines the upper-pole mass
(arrows). L, Liver; R, right kidney. (Courtesy of Dr. Erika Rubesova, Stanford University.)
invasion and is usually treated by simple nephrectomy. Sonography
demonstrates a mass arising within the kidney, similar in appearance
to a Wilms tumor. It is solid but may have cystic-appearing
areas of hemorrhage and necrosis (Fig. 52.65). here are two
main pathological types: the classic variant, and the more aggressive
cellular variant. he cellular variant is characterized by
hemorrhage and necrosis, with invasion of perirenal fat and
adjacent organs, and local recurrence. Cystic components are
readily identiied by ultrasound, whereas central hemorrhage is
better depicted by CT. MRI shows high sensitivity for both. 203
Renal Cell Carcinoma
Renal cell carcinoma is rare in childhood. It occurs later than
Wilms tumor, with a median age at diagnosis ranging between
8 and 17 years. Unlike adults, in whom up to 67% of renal cell
carcinomas are found incidentally, most children are symptomatic,
and approximately 30% have metastatic disease on presentation.
here is also no gender predominance in children. Children and
adolescents with renal cell carcinoma have much higher rates
of translocation tumors than adults. Children with translocation
tumors tend to have indolent disease with good outcomes
compared with adults, even those with advanced disease. 204 Renal
cell carcinoma cannot be distinguished from Wilms tumor by
imaging, but calciication is more common (25%-53%) in renal
cell carcinoma (Fig. 52.66) than in Wilms tumor (9%). 205
Angiomyolipoma
Angiomyolipoma is a form of hamartoma that can be complicated
by hemorrhage and/or rupture. In children, these tumors are
usually multiple and are associated with tuberous sclerosis.
Sonography typically shows multiple masses of varying echogenicity
depending on their fat content. Masses containing a
large amount of fat are very echogenic 206,207 (Fig. 52.67).
Multilocular Cystic Nephroma
Multilocular cystic nephroma is a rare lesion that is generally
considered benign. It can occur at any age but is uncommon in
children younger than 2 years. he mass is composed of multiple
cysts of varying size joined by connective tissue septa. It may
be diicult to distinguish from a cystic, well-diferentiated Wilms
tumor containing nephroblastoma components in the walls of
the cysts. Sonography demonstrates a well-circumscribed,
multiloculated cystic mass with septations (Fig. 52.68). Some
suggest a malignant potential for these lesions and recommend
nephrectomy. 208-210
Renal Lymphoma
Lymphomatous involvement of the kidney is usually a secondary
process and can be seen on sonography as single or multiple,
relatively hypoechoic or slightly echogenic masses within the
kidney. he kidney may be enlarged and lobulated in outline.
Difuse iniltration of the kidney can also occur 211,212 (Fig. 52.69,
Video 52.8).
Bladder Tumors
Primary tumors of the lower urinary tract are uncommon in
children. Sarcoma botryoides is a rhabdomyosarcoma arising
in the bladder base in males, manifesting with bladder outlet
obstruction (Fig. 52.70). In girls, this rare tumor typically occurs
in the uterus or vagina. 78,213,214
PEDIATRIC ADRENAL SONOGRAPHY
Normal Anatomy
he adrenal gland is relatively prominent in the neonate and is
easily visualized with ultrasound above the kidneys. At birth,
the adrenal gland is relatively large, representing 0.2% to 0.3%
of total body weight, compared with 0.001% in adults. here is
a linear relationship between body weight and gland length in
healthy neonates. However, in premature neonates, gestational
age and gland length have a linear relationship. In the neonate,
there is a thick fetal zone that occupies about 80% of the adrenal
cortex. Ater birth, the fetal zone of the adrenal cortex undergoes
involution. he linear dimensions of the adrenal continually
decrease during the irst 6 months of life (Table 52.10). In addition,
the appearance of the adrenal gland changes as the cortex
involutes, the overall echogenicity of the gland increases, and