What is Wilms’ tumour?

Wilms’ tumour (sometimes called nephroblastoma) is a very rare type of kidney cancer that affects children. It is named after a German doctor, Dr Max Wilms (1867-1918), who first described it. Wilms’ tumour afflicts about 80 children per year in the UK, and is curable in 90% of cases.

A nephroblastoma is abnormal tissue that grows on the outer part of one or both kidneys. Children with this condition are at risk of developing a Wilms’ tumour. It is thought that nephroblastomas originate from specialised cells in the developing embryo known as metanephric blastema, which are involved in the development of the child’s kidney while they are still in the womb. These cells usually disappear at birth, but in many children with Wilms’ tumour, cells called nephrogenic rests can still be found on the kidneys.

Wilms’ tumours are categorised as favourable or unfavourable, depending on how the tumour cells appear under the microscope. Unfavourable tumour cells look very large and not like normal kidney cells. These cells are called anaplastic (large and abnormal), and the cancer is less likely to be cured. However, about 95% of Wilms’ tumours have favourable histology and a high chance of a cure.