Epidemiology

• Peak incidence: between 2 and 5 years
• Most common malignant neoplasm of the kidney in children

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Etiology

Can be associated with loss-of-function mutations of tumor suppressor genes WT1 or WT2 on chromosome 11 (W11ms tumor).

Associated syndromes

• WAGR syndrome: Deletion of the 11p13 band leads to the deletion of the WT1 gene and other genes, such as PAX6.
  • Nephroblastoma
  • Aniridia
  • Genitourinary anomalies
    • Pseudohermaphroditism, undescended testes in males (due to gonadal dysgenesis)
    • Early-onset nephrotic syndrome
  • Range of intellectual disability
• Denys-Drash syndrome: a mild form of WAGR without aniridia or intellectual disability.
  • Nephroblastoma
  • Pseudohermaphroditism, undescended testes in males (due to gonadal dysgenesis)
  • Early-onset nephrotic syndrome caused by diffuse mesangial sclerosis
• Beckwith-Wiedemann syndrome: mutations of the WT2 gene

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Pathophysiology

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Clinical features

Abdominal symptoms

• Palpable abdominal mass (often found incidentally)
  • Non-tender
  • Unilateral and large but not crossing midline
  • Smooth and firm
• Abdominal pain (∼ 40% of cases)

Other signs and symptoms

• Hematuria (∼ 25% of cases)
• Hypertension (∼ 25% of cases)

Tip

Nephroblastoma should be suspected in a toddler with a non-tender abdominal mass, especially if it is firm, smooth, and associated with hematuria and/or hypertension.

Warning

Careless palpation of a nephroblastoma can result in rupture of the renal capsule and tumor spillage!

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Diagnostics

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Treatment

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