Find the organ of origin first (claw sign of the kidney, or displacement from outside it), then the discriminators — calcification, vessel encasement versus displacement, crossing the midline — and stage the spread.
Orient first
- Age is the first clue: neuroblastoma is usually under 2 years, Wilms tumour typically 3–4 years; hepatoblastoma in infants.
- Wilms tumour arises FROM the kidney (claw sign), displaces vessels, spreads into the renal vein and IVC, and calcifies rarely.
- Neuroblastoma arises from the adrenal or sympathetic chain, ENCASES vessels, crosses the midline, calcifies in most cases, and may extend into the spinal canal through the foramina.
Acquire the study
- Curvilinear and linear probes; colour Doppler of the renal vein and IVC.
The manoeuvre
- Organ of origin: renal parenchyma stretched around the mass (claw sign) versus a separate mass indenting the kidney.
- Echogenic foci with shadowing (calcification) favour neuroblastoma.
- Colour Doppler: tumour thrombus in the renal vein and IVC up to the right atrium.
- The other kidney (bilateral Wilms), the liver and nodes.
What confirms it
- A mass whose origin and behaviour fit one entity, with the staging features listed.
What licenses you to exclude it
- A normal ultrasound excludes a palpable solid mass; it does not stage one.
The classic misread
- Missing a small contralateral renal lesion in a child with Wilms tumour.