What is the role of ultrasonography in Wilms tumor imaging?

Updated: Mar 04, 2019
  • Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR; Chief Editor: Eugene C Lin, MD  more...
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Answer

Ultrasonography is an excellent diagnostic modality for evaluating children with a suspected abdominal mass (see the images below). Its major advantages are its lack of radiation, noninvasiveness, and ability to be repeated as needed with no harm to the child. Ultrasonography offers multiplanar capability and can be used to accurately guide biopsy. In addition, 3-dimensional capability is available. The use of ultrasonographic contrast medium is promising. Sedation and a general anesthetic are seldom required, and resolution of both solid and cystic tumors is excellent. Doppler ultrasonography is the image modality of choice for evaluating patency of the renal vein and IVC. [8, 9, 36, 20]

This 6-year-old male child with hematuria was refe This 6-year-old male child with hematuria was referred for a renal ultrasound scan. The scan shows a 6 x 8 cm solid mass at the lower pole of the right kidney displacing part of the collecting system in a cephalad direction. The mass is of uniform echogenicity with a vague small central hypoechoic area suggestive of tumor necrosis.
Axial US image shows a solid 4.5-cm solid mass ant Axial US image shows a solid 4.5-cm solid mass anterior cortex, lower pole of the left kidney. Image courtesy of Dr. Pedro Daltro and Dr. Edson Marchiori, Port Allegre, Brazil. edmarchiori@gmail.com
Sagittal US scan of the left kidney (same patient Sagittal US scan of the left kidney (same patient as in the previous image). Image courtesy of Dr. Pedro Daltro and Dr. Edson Marchiori, Port Allegre, Brazil. edmarchiori@gmail.com
Color Doppler US scan of the right kidney in a sag Color Doppler US scan of the right kidney in a sagittal plane shows a 13-cm upper-pole, mainly solid tumor with a heterogeneous echo pattern displacing the functioning component of the kidney inferiorly.
Color Doppler US scan of the right kidney in an ax Color Doppler US scan of the right kidney in an axial plane shows a 13-cm upper-pole, mainly solid tumor with a heterogeneous echo pattern displacing the vessels and crossing the midline (same patient as in previous image). Images courtesy Dr. Pedro Daltro and Dr. Edson Marchiori, Port Allegre, Brazil. edmarchiori@gmail.com

The initial diagnosis of a suspected renal or abdominal mass, with a possible renal vein or IVC thrombus in children is usually confirmed by using ultrasonography. Sonograms provide information regarding the liver and the unaffected kidney and confirms an intrarenal location of the tumor. Ultrasonography is also an excellent screening tool for syndromes associated with Wilms tumors, such as nephroblastomatosis, hemihypertrophy, horseshoe kidney, Beckwith-Wiedemann syndrome, chromosomal abnormalities, Denys-Drash syndrome, and Perlmann syndrome. Renal involvement is usually present, but rare extrarenal variants have also been reported, both within the abdomen and at distal extra-abdominal sites.

Approximately 1 in 10 children with Beckwith-Wiedemann syndrome develops cancer. However the risk is high enough to warrant screening for cancer. The incidence of cancer is age dependent, with the risk being high in the first 4 years, low at 5-10 years, and near the baseline for the general population by 10 years of age.

The major reason for cancer screening is because early identification improves survival and decreases morbidity associated with treatment. For screening, ultrasonography is performed every 3 months.

Screening does increase the number of children in whom the tumor can be removed while part of the kidney is spared. The current recommendation is the performance of ultrasonography every 3 months until 6-8 years of age. For children with Beckwith-Wiedemann syndrome and hemihypertrophy, the adrenal glands and liver should be evaluated in addition to the kidney because they are also at risk for developing hepatoblastoma and neuroblastoma.

Egeler and associates showed that a preoperative imaging protocol based on predominantly chest radiography and abdominal ultrasonography does not reduce the survival of patients with Wilms tumors. [29]

Skoldenberg et al retrospectively assessed the safety, sensitivity, and specificity of biopsy done with an ultrasonography-guided cutting needle (needle diameter 1.2 mm) in 28 children with renal tumors. All Wilms tumors were correctly diagnosed. The overall sensitivity was 76%. Use of the ultrasonography-guided cutting needle proved to be a safe procedure, and it was not associated with recurrence along the needle tract or other serious complications. [37]

Sklair-Levy et al performed 69 percutaneous image-guided needle biopsy procedures in 57 children. Their data suggested that image-guided needle biopsy is an excellent tool for diagnosing solid tumors in the pediatric population. Negative results should be considered nondiagnostic and followed up with excisional surgical biopsy when the clinical suspicion of malignancy is high. [38]

In a study of ultrasound and laboratory findings in Wilms tumor survivors with a solitary kidney, signs of kidney damage were seen in 22 of 53 (41.5%) patients on ultrasonography. The most frequently detected abnormalities were hyperechoic rings around renal pyramids (28.3% of patients). Hypertrophy of the solitary kidney occurred in 71,7% of cases. [20]


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