Wilms tumour

Wilm's tumour is a specific type of nephroblastoma deriving from embryonic kidney tissue. It is the most common renal tumour in children, mostly seen in children under 5 years of age.

It usually has an excellent prognosis (90% long-term survival rate), especially if detected early. However, metastatic disease does develop in <10% of children.

Pathophysiology

Wilms tumour involves genetic mutations that affect the normal development of the kidneys. About 1/3rd of the cases have to do with mutations on the Wilms tumour genes located on chromosome 11 (WT1 and WT2 genes). These mutations lead to desregulation in cellular proliferation and differentiation. Other genes implicated include WTX on chromosome 3 as well as TP53.

Wilms tumour is associated with certain congenital overgrowth syndromes as well as other non-overgrowth syndromes:

• Congenital overgrowth syndromes - these are are syndromes characterised by excessive growth and development of certain organs.

• ⭐️ Beckwith-Wiedemann syndrome
1. Wilms tumour
2. Macroglossia
3. Organomegaly
4. Hemihypertrophy - hypertrophy on one side of the body only.
5. Hyperinsulinaemia (leading to hypoglycaemia)
6. Congenital hernias - such as umbilical hernia or omphalocoele.

• Simpson-Golabi-Behmel syndrome
1. Wilms tumour
2. Macrosomia
3. Widely spaced eyes
4. Broad nose
5. Macroglossia with a deep furrow in the middle
6. Coarse facial features

• Perlman syndrome
1. Nephromegaly
2. Wilms tumour
3. Neonatal macrosomia.

Other associated syndromes (non-overgrowth) are:

• Denys-Drash syndrome
• Wilms tumour
• Early-onset nephrotic syndrome
• Male pseudohermaphroditism - this is when there are testes and external genitalia resembling a female or are ambiguous.

• WAGR syndrome
• Wilms tumour
• Aniridia (absent irises)
• Genitourinary malformations
• Retardation (mental retardation)

😷 Presentation

Common symptoms include:

• ⭐️ Unilateral painless abdominal/flank mass - but it could be bilateral as well.
• Abdominal distension - as the tumour grows.
• Abdominal pain - may be due to intra-abdominal spread and/or tumour rupture.
• Hypertension - due to the compression of renal vasculature or renin hypersecretion.

Uncommon:

• Lethargy & fatigue
• Weight loss
• Fever
• Respiratory symptoms - as this is the most common site of metastasis.

🔍 Investigations

• 🥇 Ultrasound scan - this is the first-line modality. Shows an evenly echogenic, heterogenous, mainly solid mass arising from kidney.
• CT & MRI - to stage the tumour.
• 🏆 Biopsy for tumour histology
• Urinalysis - may show haematuria.
• Bloods are usually normal, but we might see:
• Anaemia and rarely polycythaemia.
• Decreased creatinine clearance
• Increased AST, ALT, bilirubin due to hepatic metastasis.
• Increased calcium due to bone metastasis.

🧰 Management