Wilms' Tumour

The Concept

Wilms' tumour (nephroblastoma) is the commonest renal malignancy of childhood, typically presenting in children under 5 years old. It is an embryonal tumour arising from primitive (metanephric) renal tissue, and it is important both as a paediatric surgical emergency-of-diagnosis and as one of the great successes of modern paediatric oncology, with an excellent prognosis when treated appropriately.

Clinical Features

The classic presentation is a large, smooth abdominal (flank) mass in an otherwise well young child, often noticed by a parent during bathing. The mass characteristically does not cross the midline (a helpful distinction from neuroblastoma, which does). Other features include haematuria, abdominal pain and hypertension (from renin). It may be associated with syndromes such as WAGR and Beckwith-Wiedemann.

Investigation & Management

Diagnosis and staging use ultrasound and CT; a key principle is to avoid percutaneous biopsy where possible, because rupturing the tumour capsule risks spreading the tumour and upstaging it. Treatment is a combination of nephrectomy and chemotherapy (with radiotherapy for higher-stage disease), delivered by a specialist paediatric oncology team, and gives high cure rates.

Contrast with Neuroblastoma

A classic paediatric exam contrast is Wilms' tumour versus neuroblastoma. Both cause an abdominal mass in a young child, but the Wilms' (renal) mass does not cross the midline and the child is usually well, whereas the neuroblastoma (from the adrenal/sympathetic chain) often crosses the midline, is irregular, and the child is systemically unwell (with features such as periorbital bruising and catecholamine effects). This distinction, plus the age and imaging, points to the diagnosis.

The Bottom Line

Wilms' tumour is the commonest childhood renal cancer, a flank mass that does not cross the midline, diagnosed on imaging (avoiding biopsy) and treated by nephrectomy plus chemotherapy with an excellent prognosis.

A Note on Prognosis & Stage

Wilms' tumour is one of paediatric oncology's success stories, with overall cure rates above 85–90% when managed by a specialist team, because it responds well to combined nephrectomy and chemotherapy. Prognosis depends on the stage and the histology (favourable vs anaplastic), and avoiding tumour rupture at surgery (which upstages the disease and worsens outcome) is a key surgical principle — reinforcing why biopsy and rough handling are avoided.

Avoid vigorous palpation — risk of rupture and seeding.

• Wilms' tumour (nephroblastoma) = commonest childhood renal cancer (under 5 years); embryonal tumour.
• Large smooth flank mass in a well child that does not cross the midline (vs neuroblastoma, which does); haematuria, hypertension; syndromes (WAGR, Beckwith-Wiedemann).
• Ultrasound + CT for diagnosis/staging; avoid biopsy (risk of rupture/spread/upstaging).
• Treat with nephrectomy + chemotherapy (± radiotherapy); excellent prognosis.