A 5-year-old child is found to have a large unilateral abdominal mass on ultrasound that is intrarenal, well-defined, and heterogeneous with solid and cystic components. CT shows the mass displacing but not invading the aorta. What is the most likely radiological diagnosis?

• A Wilms tumour (nephroblastoma) ✓
• B Neuroblastoma
• C Renal cell carcinoma
• D Angiomyolipoma

Explanation

Wilms tumour is the most common renal malignancy in children, typically presenting between 3–5 years as a large unilateral intrarenal mass that displaces but does not encase the aorta (unlike neuroblastoma which encases and displaces vessels). CT shows heterogeneous enhancement with claw of renal parenchyma around the mass. Neuroblastoma arises from the adrenal/paraspinal sympathetic chain, is often calcified, and characteristically encases vessels. RCC is extremely rare in this age group. Angiomyolipoma contains macroscopic fat on CT, seen in tuberous sclerosis.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.