Nephroblastoma of the kidney (Wilms tumor)
Clinical story
A 2 1/2 years old boy presented with hematuria and abdominal pain. A large tumor was found in the right kidney. Fine-needle aspiration cytology showed malignant cells and the kidney was removed. Grossly, a protruding tumor of 4.5 cm was found in the upper pole, growing into, but not through the capsule. The cut surface showed a solid tumor with yellow to more white areas.
Comments
The tumor shows the characteristic forms of differentiation: Epithelial structures in the form of sheets and nodules of cells with distinct cytoplasm and gland-like structures; areas of blastematous differentiation with cells with a high nuclear/cytoplasmic ratio, and areas of mesenchymal differentiation with strands of fibroblast like cells. No severe atypia is found. Between the tumor and the adjacent normal kidney tissue is an area of reactive fibrosis.
Learning goals
Recognize the typical triphasic pattern of this tumor.