Squamous predominant teratoid Wilms' tumor.

Teratoid Wilms tumor is an unusual histological variant of nephroblastoma with predominant heterologous component. Frequently present components include adipose tissue, glial tissue, muscle, cartilage or bone. The presence of squamous epithelial component on the other hand is rarely reported. We describe a case of unilateral teratoid Wilms' tumor in a 2-year-old boy with lung metastasis. In this case, tumor showed the familiar triphasic histologic pattern of nephroblastoma along with extensive squamous epithelial component.