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Definition

Wilms tumor is the most common primary malignant renal tumor of childhood and is the paradigm for multimodal management of a pediatric malignant solid tumor.

Epidemiology

The incidence of Wilms tumor is 10 cases per million among white children younger than 15 years, and the male to female ratio is low. The incidence is approximately three times higher for blacks in the United States and Africa than for eastern Asians.

Clinical Manifestation

• Abdominal swelling or abdominal mass (most common complain).
• Abdominal mass
• Gross hematuria
• Fever
• Hypertension (about 25% of cases).

Differential Diagnosis

• Splenomegaly
• Neuroblastoma (often arises in the celiac axis or extends across the midline because of lymph node involvement).

Imaging Studies

• Ultrasonography
   The patency of the inferior vena cava.
• CT Scans of the abdomen with contrast
  To evaluate the nature and extent of the mass, may suggest apparent extension of the tumor into adjacent      structures, such as the liver, spleen, or colon.
• Plain chest radiographs, CT scans of chest
  To determine whether pulmonary metastasis is present.
• Brain CT scans or MRI
  For all children with clear cell sarcoma of the kidney or rhabdoid tumor of the kidney

Staging


Treatment

Surgery
• Surgical removal of the primary tumor remains the cornerstone of Wilms tumor therapy.
• Assessment of tumor spread at surgery is essential for accurate staging and for subsequent determination of the need for radiation therapy and administration of the appropriate chemotherapeutic regimen. Every effort must be made to remove the tumor without causing spread or spill.

Radiotherapy
• The National Wilms Tumor Studies have shown that patients with stage I and II tumors and favorable histologic findings who receive vincristine and actinomycin D do not need postoperative irradiation.

Chemotherapy
According to National Wilms Tumor Study Group findings, the chemotherapy regimens recommended for children with favorable histologic findings of Wilms tumor depend on tumor stage:
• Stage I or II, vincristine and actinomycin D for 18 weeks
• Stage III or IV, a combination of vincristine, actinomycin D, and doxorubicin for 21 weeks.

Prognosis

The most important determinant of prognosis :
• Tumor size
• Age of the patient
• Presence of lymph node metastasis
• Local features of the tumor, such as capsular or vascular invasion.