Wilms Tumor

Content of This Page

1- Definition & Types

2- Causes (Aetiology)

3- Pathophysiology

4- Clinical Features & Examination

5- Investigations

6- Management

7- Complications

8- Core Concepts

Definition & Types

Wilms tumour, also known as nephroblastoma, is the most common malignant renal tumour in children, typically presenting before the age of 5 years.

  • It is derived from embryonal renal tissue.

  • Histologically, Wilms tumour is usually triphasic, composed of:

    • Blastemal (undifferentiated)

    • Epithelial (tubules and glomeruli-like structures)

    • Stromal (connective tissue components)

© image from Wikimedia Commons

Causes (Aetiology)

Wilms tumour is mostly sporadic, but about 10% are associated with congenital syndromes, especially those involving abnormalities in WT1 gene expression:

  • WAGR syndrome: Wilms tumour, Aniridia, Genitourinary anomalies, and mental Retardation

  • Denys–Drash syndrome: nephropathy, ambiguous genitalia, and high Wilms risk

  • Beckwith–Wiedemann syndrome: overgrowth disorder with macroglossia, organomegaly, and hemihypertrophy

Family history is rare but may occur in inherited cases.

Pathophysiology

  • Results from mutations affecting renal development genes, especially the WT1 gene on chromosome 11p13.

  • Tumour arises from nephrogenic rests—embryonic remnants that fail to mature properly.

  • These rests may transform into Wilms tumour under influence of additional genetic alterations.

Clinical Features & Examination

Most children present with:

  • Abdominal mass (usually painless and smooth)

  • Haematuria (may be microscopic)

  • Hypertension (due to renin production)

  • Abdominal pain (less common)

  • Fever or malaise

On examination:

  • A firm, non-tender flank mass is often palpable.

  • Ensure gentle palpation—vigorous handling can risk tumour rupture and upstaging.

Investigations

Initial imaging:

  • Ultrasound of the abdomen: First-line to detect renal mass and assess the contralateral kidney.

Further staging:

  • CT or MRI of the abdomen and chest:

    • Assess local spread and vascular invasion.

    • Identify lung metastases, which are common.

Other tests:

  • Urinalysis: For haematuria.

  • Renal function tests: Assess both kidneys.

  • Genetic testing: In cases with associated syndromes or bilateral disease.

Histopathology of Wilms' tumor © image from Wikimedia Commons

Management

Management is multimodal and highly protocol-driven, typically under paediatric oncology teams.

  • Neoadjuvant chemotherapy: Often given before surgery to reduce tumour size.

  • Surgical nephrectomy: Standard treatment for unilateral tumours.

  • Postoperative chemotherapy: Depending on histology and stage.

  • Radiotherapy: Reserved for advanced or unfavourable histology cases.

Bilateral disease:

  • Aim to preserve renal tissue—partial nephrectomy or staged resections.

Complications

  • Local recurrence or metastasis: Especially to lungs and liver.

  • Renal insufficiency: More likely with bilateral disease.

  • Hypertension

  • Treatment-related side effects:

    • Chemotherapy: risk of myelosuppression, infertility

    • Radiotherapy: growth disturbances, second malignancies

Core Concepts

  • Wilms tumour is a curable childhood cancer with a survival rate >85% in localized disease.

  • Prompt imaging in any child with an abdominal mass is essential.

  • Management is based on well-defined oncology protocols involving chemotherapy, surgery, and sometimes radiotherapy.

  • Screen for associated syndromes and assess the contralateral kidney.

  • Early diagnosis and multidisciplinary care are critical for optimal outcomes.

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