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# Wilms tumour (nephroblastoma)

Wilms tumour is the most common kidney cancer in young children, usually found as a painless belly mass. Most children are cured with treatment.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Kidneys](https://durgical.com/en/anatomy/kidney/)
- [Renal pelvis](https://durgical.com/en/anatomy/renal-pelvis/)
- [Left renal vein](https://durgical.com/en/anatomy/right-renal-vein/)
- [Right renal vein](https://durgical.com/en/anatomy/right-renal-vein-abdomen/)
- [Inferior vena cava](https://durgical.com/en/anatomy/inferior-vena-cava/)
- [Abdominal aorta](https://durgical.com/en/anatomy/abdominal-aorta/)
- [Left adrenal gland](https://durgical.com/en/anatomy/suprarenal-gland/)
- [Iris](https://durgical.com/en/anatomy/iris/)

## In embryology

- [Kidney: pronephros, mesonephros, metanephros and ascent](https://durgical.com/en/embryology/kidney-pronephros-mesonephros-metanephros-and-ascent/)
- [Horseshoe kidney and renal ectopia](https://durgical.com/en/embryology/horseshoe-kidney-and-renal-ectopia/)

## In the clinical exam

- [Kidney palpation: bimanual palpation and ballottement](https://durgical.com/en/clinical-exam/kidney-palpation-bimanual-palpation-and-ballottement/)

## Why it happens

- [Tumour suppressor genes: RB, TP53, APC, BRCA and the two-hit hypothesis](https://durgical.com/en/general-pathology/tumour-suppressor-genes-rb-tp53-apc-brca-and-the-two-hit-hypothesis/)
- [Tumours of infancy and childhood](https://durgical.com/en/general-pathology/tumours-of-infancy-and-childhood/)
- [Genomic imprinting: Prader–Willi and Angelman](https://durgical.com/en/general-pathology/genomic-imprinting-prader-willi-and-angelman/)
- [Naming tumours: -oma, carcinoma, sarcoma, and the misleading names](https://durgical.com/en/general-pathology/naming-tumours-oma-carcinoma-sarcoma-and-the-misleading-names/)

## What it is

A malignant embryonal tumour of the kidney arising from persistent primitive renal tissue (nephrogenic rests). It is the most common renal cancer of childhood, typically in children aged 2–5 years.

## Who gets it

Accounts for about 5–6% of childhood cancers, with most cases before 5 years of age; about 5–10% are bilateral. In Latin America, children are more often diagnosed at advanced stages and access to timely treatment affects survival; Colombia includes childhood cancer in its national surveillance and care programmes.

## Causes

- Mostly sporadic
- Mutations in WT1 (11p13) or abnormalities at 11p15 (WT2) in syndromic cases

## Risk factors

- WAGR syndrome (Wilms tumour, aniridia, genitourinary anomalies, intellectual disability)
- Denys-Drash and Frasier syndromes (WT1)
- Beckwith-Wiedemann syndrome and isolated hemihypertrophy
- Genitourinary anomalies such as cryptorchidism and hypospadias
- Family history of Wilms tumour

## Pathophysiology

Embryonic kidney cells fail to mature and keep proliferating. The tumour typically has three components (blastemal, stromal and epithelial) and grows as a well-circumscribed mass within the kidney. It can extend into the renal vein and [inferior vena cava](https://durgical.com/en/anatomy/inferior-vena-cava/), and spreads mainly to the lungs. Anaplastic histology predicts a worse response to treatment.

## Classification

- Favourable histology (most cases) versus anaplastic histology
- Staging I–V (stage V: bilateral disease), used together with histology to guide therapy

## Symptoms and signs

- Painless, smooth abdominal or flank mass, often noticed by a parent while bathing or dressing the child
- Abdominal pain or swelling
- Haematuria
- Hypertension (renin secretion)
- Fever, poor appetite or weight loss
- Aniridia, hemihypertrophy or genital anomalies as clues to a syndrome

## Red flags

- Sudden abdominal pain, pallor and hypotension (tumour rupture with haemorrhage)
- Respiratory symptoms (lung metastases)
- Leg swelling or varicocele (vena cava involvement)

## Diagnosis

**Clinical**
A unilateral flank mass that does not usually cross the midline in a well-looking young child. Palpation should be gentle and limited, to avoid rupturing the tumour.

**Tests**
Complete blood count, [kidney](https://durgical.com/en/anatomy/kidney/) function, urinalysis (haematuria), coagulation tests (acquired von Willebrand disease) and [liver](https://durgical.com/en/anatomy/liver/) function. Histology from the surgical specimen confirms the type; genetic testing when a syndrome is suspected.

**Imaging**
Abdominal ultrasound first (solid renal mass, renal vein and vena cava patency), then CT or MRI of the [abdomen](https://durgical.com/en/anatomy/region/abdomen/) and [chest](https://durgical.com/en/anatomy/region/chest/) CT for lung metastases.

## Differential diagnosis

- Neuroblastoma (often crosses the midline, calcifications, raised urine catecholamines, sicker child)
- Hydronephrosis and multicystic dysplastic kidney
- Mesoblastic nephroma (infants) and other renal tumours
- Hepatoblastoma and other abdominal masses

## Goal of treatment

Cure the child with the least long-term toxicity, tailoring surgery, chemotherapy and radiotherapy to stage and histology, and preserving kidney tissue in bilateral or syndromic cases.

## Treatment

**Surgical**
Radical nephrectomy with lymph-node sampling is standard in North American protocols; nephron-sparing surgery for bilateral tumours or a single kidney.

**Medical**
Chemotherapy (agents such as vincristine, dactinomycin and doxorubicin), given before surgery in European protocols and after surgery in North American ones.

**Procedure**
Radiotherapy for higher-stage disease, anaplastic histology or lung metastases.

**Follow-up**
Nursing priorities: avoid palpating the abdomen (post a sign at the bedside), monitor blood pressure and urine output, chemotherapy care; long-term follow-up of kidney function, heart and second cancers.

## Complications

- Tumour rupture and spread
- Lung metastases
- Chronic kidney disease, especially in bilateral or syndromic cases
- Late effects of treatment: cardiotoxicity (anthracyclines), growth and fertility problems, second cancers

## Prognosis

One of the most curable childhood cancers: overall survival exceeds 90% in high-income settings with favourable histology, but is lower with anaplasia, relapse or where access to treatment is delayed.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the typical presentation of Wilms tumour?

A painless abdominal or flank mass in a well child aged 2–5 years, sometimes with haematuria or hypertension.

## Which gene is linked to Wilms tumour in WAGR syndrome?

WT1 on chromosome 11p13.

## How can Wilms tumour be distinguished clinically from neuroblastoma?

Wilms usually does not cross the midline and the child looks well; neuroblastoma often crosses the midline, calcifies and raises urine catecholamines.

## What is the key nursing precaution in a child with suspected Wilms tumour?

Do not palpate the abdomen, to avoid rupturing the tumour.

## Where does Wilms tumour most often metastasise?

To the lungs.

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## Related conditions

- [Arterial hypertension](https://durgical.com/en/conditions/arterial-hypertension/)
- [Cryptorchidism (undescended testis)](https://durgical.com/en/conditions/cryptorchidism/)
- [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/)
- [Autosomal dominant polycystic kidney disease](https://durgical.com/en/conditions/autosomal-dominant-polycystic-kidney-disease/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Wilms Tumor (PDQ®)–Patient Version](https://www.cancer.gov/types/kidney/patient/wilms-treatment-pdq) (National Cancer Institute (NCI), 2026).

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Source: https://durgical.com/en/conditions/wilms-tumour/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/wilms-tumour/