A case of teratoid Wilms’ tumour

Wilms’ tumour is the most common renal malignancy in children and the fourth most common childhood cancer. In the United States, Wilms’ tumour accounts for 6.6% of childhood malignancies, with 500 new cases presenting each year. This condition arises from pluripotent embryonal cells in the developing kidney. Pluripotency is apparent in the pathognomic triphasic histologic appearance, consisting of three components: epithelial, blastemal and stromal cells. The teratoid histological variant of Wilms’ tumour is rare, with only 16 reported cases. It is identified histologically by heterologous differentiation in the presence of other mature tissue types within a Wilms’ tumour. These mature tissues may include muscle, squamous, bone, cartilage, glial, adipose and glandular tissues. Fernandes et al. refined the definition of teratoid Wilms’ tumour by restricting it to tumours with heterologous differentiation accounting for greater than 50% of their volume.