Wilms Tumor

Wilms Tumor: Overview - Kidney Culprit

• Embryonal malignancy of the kidney; also called Nephroblastoma.
• Arises from primitive metanephric blastema cells (nephrogenic rests).
• Peak incidence: 2-5 years old.
• Most common primary renal tumor in children.
• Accounts for ~6% of all pediatric cancers.
• Typically unilateral; bilateral disease seen in 5-10% of cases.

⭐ Wilms tumor is the most common primary renal tumor of childhood, typically presenting between 2-5 years of age.

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Wilms Tumor: Patho & Genetics - Blueprint Clues

• Origin: Nephrogenic rests (persistent metanephric blastema).
• Classic triphasic histology: Blastemal, epithelial, stromal.
  • Anaplasia (focal/diffuse) indicates poor prognosis.
• Key Genetic Loci:
  • WT1 (11p13): Tumor suppressor gene.
    • 📌 WAGR syndrome: Wilms, Aniridia, Genitourinary anomalies, mental Retardation.
    • Denys-Drash syndrome (DDS): Wilms, gonadal dysgenesis, nephropathy.
  • WT2 (11p15.5, imprinting locus e.g., IGF2):
    • Beckwith-Wiedemann syndrome (BWS): Wilms, macroglossia, omphalocele, hemihypertrophy.
  • Other associated genes: CTNNB1, TP53 (anaplasia).

⭐ WT1 gene mutations on chromosome 11p13 are associated with WAGR and Denys-Drash syndromes.

Wilms Tumor: Presentation - Tummy Trouble

⭐ The most common presentation is an asymptomatic, firm, smooth abdominal mass, often discovered by a parent.

• Abdominal Mass: Most common (80%), usually unilateral, non-tender, doesn't cross midline.
• Hematuria: Gross or microscopic (10-25%).
• Hypertension: (25%) due to renin secretion by tumor.
• Other: Abdominal pain, fever, anemia, varicocele (left-sided mass).
• Rare: Acquired von Willebrand disease.

Wilms Tumor: Diagnosis & Staging - Scan Showdown

• Initial Imaging:
  • Abdominal Ultrasound (USG): Often first, detects renal mass.
• Definitive & Staging Scans:
  • CECT Abdomen & Pelvis: Gold standard. Assesses primary tumor, local spread (lymph nodes, vessels, contralateral kidney), liver.
  • MRI Abdomen: Alternative, esp. for IVC thrombus or contrast allergy.
  • Chest Imaging: CXR mandatory; CT Chest if CXR suspicious or for high-risk disease (lung metastases).
• Staging Systems:
  • NWTS/COG (North America): Primarily post-surgical staging.
  • SIOP (Europe): Allows pre-operative chemotherapy; staging adapted.

⭐ Pre-operative biopsy is generally AVOIDED if imaging is characteristic, to prevent tumor rupture and upstaging; nephrectomy serves as both diagnosis and treatment.

Wilms Tumor: Treatment & Prognosis - Treatment Triumph

• Multimodal Approach: Surgery, Chemotherapy, Radiotherapy (RT).
• Surgery: Radical nephrectomy (if unilateral); nephron-sparing for bilateral.
• Chemotherapy: Key for all stages. 📌 Vincristine, Actinomycin D (Dactinomycin), Doxorubicin (VAD regimen). Add Cyclophosphamide/Etoposide for high-risk.
• Radiotherapy: For Stage III/IV, focal anaplasia, or positive margins.

⭐ Histology (favorable vs. unfavorable/anaplastic) is the most important prognostic factor influencing treatment intensity and outcome.

• Prognosis: Excellent for favorable histology (FH); >90% survival. Anaplastic histology has poorer prognosis.

High‑Yield Points - ⚡ Biggest Takeaways

• Most common childhood renal malignancy; peak age 3-4 years.
• Key associations: WAGR syndrome (WT1 deletion), Denys-Drash syndrome (WT1 mutation), Beckwith-Wiedemann syndrome (WT2 mutation).
• Classic presentation: painless, palpable abdominal mass. Hematuria, hypertension may occur.
• Triphasic histology (blastemal, epithelial, stromal); anaplasia indicates poor prognosis.
• Lungs are the most common site for metastasis.
• Treatment: Nephrectomy & chemotherapy (Vincristine, Actinomycin-D). Radiotherapy for advanced/unfavorable.
• Overall good prognosis, especially with favorable histology and early stage.