Wilms Tumor (Nephroblastoma)

Key Features

• Approximately 460 new cases occur each year in the United States, representing 5–6% of cancers in children younger than 15 years

• Second most common abdominal tumor in children after neuroblastoma

• Occurrence is sporadic

• Median age at diagnosis is related both to gender and laterality

  • Diagnosed earlier in males than females

  • Bilateral tumors present at a younger age than unilateral tumors

• Occurs most commonly between ages 2 and 5 years; it is unusual after age 6 years

Clinical Findings

• Increasing abdominal size is presenting symptom in most children

• Abdominal mass can be asymptomatic and discovered incidentally by a parent or health care provider

• Mass is usually smooth and firm, well demarcated, and rarely crosses the midline, though it can extend inferiorly into the pelvis

• About 25% of patients are hypertensive at presentation

• Gross hematuria is an uncommon presentation, although microscopic hematuria occurs in approximately 25% of patients

Diagnosis

• Complete blood cell count is usually normal; some patients have anemia secondary to hemorrhage into the tumor

• Blood urea nitrogen and serum creatinine are usually normal

• Urinalysis may show some blood or leukocytes

• Ultrasonography or CT of the abdomen

  • Should establish the presence of an intrarenal mass

  • Contralateral kidney should be assessed for presence and function as well as synchronous Wilms tumor

• Ultrasonography with Doppler flow should be done to evaluate the inferior vena cava for the presence and extent of tumor propagation

• The liver should be imaged for the presence of metastatic disease

• Chest CT scan should be obtained to determine whether pulmonary metastases are present

Treatment

• First step is surgical exploration of the abdomen via an anterior surgical approach

  • Allows for inspection and palpation of the contralateral kidney

  • Liver and lymph nodes are inspected and suspicious areas biopsied or excised

  • En bloc resection of the tumor is performed

• Patients with stage III or IV Wilms tumor

  • Require radiation therapy to the tumor bed and to sites of metastatic disease

  • Chemotherapy is optimally begun within 5 days after surgery

  • Radiation therapy should be started within 10 days

• Stage V (bilateral Wilms tumor) disease

  • Possible bilateral renal biopsies followed by chemotherapy and second-look renal-sparing surgery

  • Radiation therapy may also be necessary