Wilms tumor, also called nephroblastoma, is a malignant kidney tumor that primarily occurs in young children, most often between ages 1 and 5. It is the commonest pediatric renal malignancy and usually presents as an asymptomatic abdominal mass discovered by a caregiver or clinician. Other presentations include abdominal pain, blood in the urine, fever or high blood pressure.

Characteristics

Microscopically Wilms tumor frequently shows a mixture of cell types (blastemal, epithelial and stromal elements), and its appearance can vary from well-differentiated structures to undifferentiated small blue cells. Tumors are generally unilateral, although bilateral disease occurs in a minority of children and requires special management to preserve kidney function.

Causes and genetic associations

Most cases are sporadic, but several syndromes and gene changes raise risk. Alterations in the WT1 and WT2 regions on chromosome 11 are well known; syndromes such as WAGR, Denys–Drash and Beckwith–Wiedemann carry an elevated risk. Genetic testing and careful surveillance are recommended for children with these conditions.

Diagnosis and staging

  • Initial evaluation often includes abdominal ultrasound and cross-sectional imaging (CT or MRI) to define the mass and look for spread.
  • Chest imaging assesses for lung metastases; staging guides treatment planning.
  • Biopsy is sometimes used but many centers proceed to nephrectomy depending on protocols.

Treatment and prognosis

Main treatments combine surgery (typically radical nephrectomy), multi-agent chemotherapy and, in selected cases, radiotherapy. Treatment protocols developed by pediatric oncology groups have produced high cure rates: overall long-term survival is excellent when tumors are detected and treated promptly. For more information on classification and management see kidney cancer resources and outcomes data indicating an excellent prognosis.

Follow-up and notable facts

Long-term follow-up monitors for recurrence, late effects of therapy and renal function, especially when one kidney remains. Distinguishing Wilms tumor from other pediatric abdominal masses such as neuroblastoma is important because treatment differs. Early detection and treatment significantly improve outcomes.