Paediatrics: Wilms’ tumour (nephroblastoma)

Wilms’ tumour (nephroblastoma)

This is an embryonal tumour of the kidney representing 6–7% of all child-hood malignancies. Up to 75% present at <4yrs of age (90% <7yrs). Most causes are sporadic, but 1% have an affected family member. Wilms’ tumour may be associated with the following conditions.

·  Genitourinary abnormalities, e.g. horseshoe kidney, hypospadias.

·  Hemihypertrophy syndrome.

·  Aniridia.

·  BWS.

·  Wilms’, aniridia gonadal dyslasia, retardation (WAGR) complex.

·  Denys Drash syndrome (nephropathy and genital abnormalities).

·  Perlman syndrome.

Mutations of the WT1 tumour suppressor gene on chromosome 11p13 detected in Wilms’ tumours; abnormalities of 11p15 are also implicated, associated with BWS.

Presentation 

Mostly as a visible or palpable abdominal mass. Usually painless. Haematuria and hypertension may also be seen.

Site

Bilateral cases are unusual and more often associated with genetic pre-disposition. Extrarenal Wilms’ tumours are very rare. Metastases occur in 10% of cases, most commonly to the lung.

Investigations

·  Abdominal US.

·  CT scan of abdomen (‘claw’ sign in involved kidney).

·  CXR or CT.

·  Urine catecholamines to exclude neuroblastoma (prior to anaesthetic).

·  Blood count and coagulation studies (a transient acquired von Willebrand-like syndrome is recognized and resolves with treatment).

Treatment

·  Surgical excision required.

·  Chemotherapy is used for all tumours. In stage I disease (complete resection of tumour without breach of renal capsule) is curable with vincristine, sometimes including dactinomycin which is also used for stage II disease. In higher-stage disease, doxorubicin is added.

In bilateral (stage V) disease, the aim is to maximize response to chemotherapy prior to performing bilateral nephron-sparing surgery.

·  Local or abdominal radiotherapy required for incomplete resection (stage III disease). In the presence of metastases (stage IV), surgery to primary tumour is delayed until resolution of metastaseswith chemotherapy and radiotherapy is also added. Carboplatin, cyclophosphamide, and etoposide are usually reserved for unresponsive or recurrent disease.

Prognosis 

Overall survival ranges from 770% for stage IV disease to >95% for stage I.

Relapse

·Follow-up should include regular CXR as well as abdominal ultrasound as pulmonary relapse is twice as common as local recurrence.

·Surgery, second-line chemotherapy, and radiotherapy (if not previously received) may all be applied depending on stage. Cure is achievable following second remission.

Nephroblastomatosis

Multiple foci of premalignant tissue, also known as nephrogenic rests, characterize this condition. They may be observed on renal US and CT scan. The condition is associated with Wilms’ tumour, but may exist with-out tumour formation (seen on 1% of routine post-mortem examinations). Close monitoring is required due to risk of subsequent tumour forma-tion.