Subtitle: A visual summary of paediatric renal tumours: Wilms tumour and anaplasia, congenital mesoblastic nephroma, clear cell sarcoma, rhabdoid tumour, ossifying renal tumour of infancy and metanephric tumours, with ages, genetics and 10 MCQs.
Author: PathologyMCQ Editorial Board
Category: Paediatric and Renal Pathology
Last Updated: October 2026
Read Time: 7 minutes
At-a-Glance
- Wilms tumour is the commonest paediatric renal tumour (peak 2–5 years): triphasic blastema, epithelium and stroma; anaplasia (TP53) predicts poor response.
- Age is a strong clue: mesoblastic nephroma and ossifying renal tumour in infants; rhabdoid tumour under 2 years; RCC in older children.
- Genetics: CMN (ETV6::NTRK3 or EGFR ITD), clear cell sarcoma (BCOR ITD), rhabdoid tumour (SMARCB1 loss), metanephric adenoma (BRAF V600E).
- Metastatic patterns: clear cell sarcoma to bone; rhabdoid tumour with synchronous brain AT/RT.
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Summary Table
Paediatric renal tumours at a glance
| Tumour | Usual age | Clinical clue | Genetics |
|---|---|---|---|
| Wilms tumour | 2–5 years | Abdominal mass; WAGR, Denys–Drash, Beckwith–Wiedemann | WT1, CTNNB1, WTX; TP53 in anaplasia |
| Congenital mesoblastic nephroma | 0–3 months | Commonest renal tumour in neonates | Cellular: ETV6::NTRK3; classic: EGFR ITD |
| Clear cell sarcoma | 1–4 years | Skeletal metastasis | BCOR ITD; YWHAE::NUTM2; BCOR::CCNB3 |
| Ossifying renal tumour of infancy | 0–1 year | Calcified mass in the collecting system | Trisomy 4 in some |
| Rhabdoid tumour | 6 months–2 years | Associated with brain AT/RT; hypercalcaemia | SMARCB1 (rarely SMARCA4) loss |
| Metanephric adenoma | Any age, often adults | Polycythaemia in some | BRAF V600E |
| Renal cell carcinoma | Older children, adolescents | TFE3/TFEB translocation RCC most common | MiT family rearrangement |
Wilms Tumour (Nephroblastoma)
- Histology: triphasic – blastemal, epithelial (tubules, glomeruloid structures) and stromal elements (including skeletal muscle, cartilage).
- IHC: WT1 nuclear (blastema and epithelium), CD56, PAX8 in epithelium.
- Anaplasia: nuclei ≥3× enlarged, hyperchromatic, with atypical multipolar mitoses; focal vs diffuse; linked to TP53 and chemoresistance.
- Precursors: nephrogenic rests (perilobar and intralobar). See perilobar vs intralobar nephrogenic rests →
- Syndromes: WAGR (11p13 deletion), Denys–Drash (WT1 missense), Beckwith–Wiedemann (11p15).
Congenital Mesoblastic Nephroma
- Commonest renal tumour in the first 3 months of life.
- Classic: fascicles of bland spindle cells, infiltrative border, resembling infantile fibromatosis.
- Cellular: sheets of plump cells with mitoses; ETV6::NTRK3, the same fusion as infantile fibrosarcoma.
- Excellent prognosis after complete excision.
Clear Cell Sarcoma of Kidney
- Cords and nests of pale cells separated by delicate, arborising “chicken-wire” vessels; many morphological patterns.
- Associated with skeletal metastasis (formerly “bone-metastasising renal tumour of childhood”).
- BCOR internal tandem duplication in most; BCOR and cyclin D1 positive on IHC; WT1 negative.
Rhabdoid Tumour of Kidney
- Highly aggressive tumour of infancy.
- Sheets of cells with vesicular nuclei, prominent nucleoli and eosinophilic hyaline cytoplasmic inclusions.
- Loss of SMARCB1 (INI1); association with synchronous or metachronous brain atypical teratoid/rhabdoid tumour.
Other Tumours to Remember
- Ossifying renal tumour of infancy: osteoid matrix with osteoblast-like and spindle cells; benign.
- Metanephric adenoma: tightly packed small uniform tubules, psammoma bodies; WT1 and CD57 positive; BRAF V600E.
- Paediatric RCC: MiT family translocation RCC (TFE3, TFEB) is the commonest type in children and adolescents.
- Cystic partially differentiated nephroblastoma and cystic nephroma (DICER1) in the cystic lesion differential.
Pictorial Summary
Test yourself further with the paediatric renal tumours quiz → and the renal pathology quiz →
Test Yourself: 10 MCQs
Paediatric renal tumours: 10 MCQs
Wilms tumour and its mimics, with instant explanations.
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More practice: the renal pathology MCQ bank →
Exam Pearls
- Wilms: triphasic; anaplasia = TP53 and poor response.
- Neonate with a renal mass: mesoblastic nephroma.
- Bone metastasis: clear cell sarcoma (BCOR ITD).
- INI1 loss and brain tumour: rhabdoid tumour.
- BRAF V600E: metanephric adenoma.
- Adolescent RCC: think TFE3/TFEB translocation.
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Related reads: Paediatric renal tumours quiz → · Nephrogenic rests →
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References
- WHO Classification of Tumours Editorial Board. Paediatric Tumours. 5th ed. IARC; 2023.
- WHO Classification of Tumours Editorial Board. Urinary and Male Genital Tumours. 5th ed. IARC; 2022.
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