Wilms tumour is a malignant paediatric kidney tumour thought to arise from metanephric precursor tissue that persists in the developing child.
Typically it occurs in early childhood with peak incidence at 3-4 years old (80% before 5 years old).
It is the most common paediatric renal mass (87%).
Wilms tumour may be bilateral in 4-13% of cases and in 2% of cases it may be familial,
related to congenital defects such as cryptorchidism,
hemihypertrophy and hypospadias,
and also related to WT1 and WT2 genes mutations.
Presentation is most frequently with a large painless abdominal mass that may arise in any portion of the kidney and expands within the renal parenchyma distorting the pelvicalyceal system and displacing surrounding structures.
Occasionally it can present with hematuria or even hypertension due to elevated plasma renin levels.
Wilms tumour is also known for invading vessels,
most commonly with tumour thrombus into the homolateral renal vein and inferior vena cava.
After presentation with abdominal mass,
diagnosis generally begins with ultrasound and then proceeds to CT and/or MRI.
Neuroblastoma is the most common solid extra-cranial childhood tumour,
arising from primordial neural crest cells along the sympathetic nervous system chain.
Just as Wilms tumour,
it is also most common on early childhood (up to 90% diagnosed before 6 years old) but with peak incidence at a younger age of 2 years old.
Approximately two-thirds are intra-abdominal and,
like Wilms tumour,
present as a growing abdominal mass.
The most common site of origin are the adrenal glands in 35% followed by the retroperitoneum in 30-35% of cases (arising from the organ of Zuckerkandl,
coelic axis or paravertebral symphatetic chain).
Both these tumours can present as large abdominal retroperitoneal masses,
closely related to the kidneys,
therefore it is important to review imaging features that can help distinguish them.