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Patient Story

A 6-year-old previously healthy boy presented to his pediatrician with abdominal fullness for one month. The child had no abdominal or gastrointestinal complaints. On examination, he had left-sided abdominal firmness. An ultrasound revealed a mass that appeared to originate from the kidney. He was referred to pediatric oncology. CT scan of the abdomen confirmed a large kidney mass with displacement of the structures within the left abdomen, most consistent with a Wilms tumor (Figure 213-1). Work-up for metastatic disease, including a chest CT was negative. The patient underwent nephrectomy (Figure 213-2). Pathology of the mass revealed Wilms tumor with favorable histology. The child received chemotherapy and has been tumor-free.

FIGURE 213-1

Large left-sided renal mass that is well circumscribed and without calcifications on transverse (A) and coronal (B) CT scan of the abdomen, in a 6-year-old boy with Wilms tumor. Note the normal appearing right kidney. (Used with permission from Stefanie Thomas, MD.)

FIGURE 213-2

Gross appearance of the large renal mass in the abdomen (A) during laparotomy and following removal (B) from the child in Figure 213-1. This mass was well-demarcated from the renal parenchyma and well encapsulated, and was confirmed to be a Wilms tumor with favorable histology. (Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography © 2012-2013. All Rights Reserved.)


Renal cancer, including Wilms tumor, accounts for approximately 6.3 percent of cancer diagnosed in children under the age of 15 years and 4.4 percent of cancer diagnosed in children and young adults under the age of 20 years.1 Treatment may include surgery, chemotherapy, and radiation. With multimodality therapy, long-term cure rates exceed 85 percent for children diagnosed with favorable histology, even in cases of higher stage disease.




  • Approximately 550 children and young adults under 20 years of age are diagnosed with renal tumors in the US each year and approximately 500 of these are Wilms tumor.1

  • Wilms tumor accounts for approximately 95 percent of all renal cancers in children under 15 years of age.

  • Wilms tumor occurs most commonly in children under age 5 years, with the highest incidence in the first 2 years of life.1

Etiology and Pathophysiology

  • Wilms tumor is an embryonal malignancy of the kidney.

  • It is believed to develop in retained nephrogenic rests which are foci of persistent embryonal kidney cells. Although nephrogenic rests may be seen in approximately 1 percent of kidneys at birth, they usually regress or differentiate early in life.2

  • Persistent nephrogenic rests outside ...

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