Paediatric renal mass differentials
Overview
Key differentials for a renal mass in a neonate or young child, centred on distinguishing mesoblastic nephroma from its mimics.
| Entity | Peak age | Behaviour | Key imaging | Classic association | Metastases |
|---|---|---|---|---|---|
| Mesoblastic nephroma | < 3 months (neonatal) | Benign | Solid intrarenal mass, variable enhancement | ETV6-NTRK3 fusion (cellular subtype) | Exceedingly rare |
| Wilms' tumour | 3-5 years | Malignant | Intrarenal, "claw sign" | WAGR, Denys-Drash, Beckwith-Wiedemann ~15% Ca2+ |
Lung, liver |
| Neuroblastoma | 1-2 years | Malignant | Displaces kidney, doesn't arise from it | Elevated urinary VMA/HVA ~90% Ca2+ on CT |
Widespread (bone marrow, liver, skin) |
| Rhabdoid tumour | ~11 months | Highly aggressive | Large, homogeneous, replaces kidney | CNS AT/RT (SMARCB1/INI1 loss) | Early, widespread |
| Clear cell sarcoma | 1-4 years | Malignant | Non-specific solid renal mass | Bone metastases ("bone-metastasising renal tumour") | Bone predilection |
| Multilocular cystic nephroma | Older children / adult women | Benign | Predominantly cystic, septated | - | None |
Quick recall
- Neonate with renal mass = mesoblastic nephroma; toddler/child = Wilms'
- Mass displacing kidney + calcification + raised catecholamines = neuroblastoma (not intrarenal)
- INI1/SMARCB1 loss + CNS lesion = rhabdoid tumour (worst prognosis of the group)
