Table 1

The revised International Society of Paediatric Oncology (SIOP) working classification of renal tumours of childhood (2001)

I Low risk tumours

Mesoblastic nephroma

Cystic partially differentiated nephroblastoma

Nephroblastoma—completely necrotic (following preoperative chemotherapy)

II Intermediate risk tumours

Nephroblastoma—epithelial type

Nephroblastoma—stromal type

Nephroblastoma—mixed type

Nephroblastoma—regressive type

Nephroblastoma—focal anaplasia type

III High risk tumours

Nephroblastoma—blastemal type

Nephroblastoma—diffuse anaplasia type

Clear cell sarcoma of the kidney

Rhabdoid tumour of the kidney