Pathology

The histology of Wilms' tumor is either favorable or unfavorable.

Favorable histology is more common (89%) and is characterized by the presence of three components:

· stroma

· blastema

· epithelial elements

Unfavorable histology is less common (3% to 13%, increasing with age) and defined by the presence of anaplasia.

Nephroblastomatosis or nephrogenic rests are microscopic areas of blastema adjacent to normal kidney parenchyma. The natural history of these rests is poorly understood, but they are almost always found in Wilms' tumor patients with the WT1 or WT2 mutation and even in a large percentage of sporadic cases.

Wilms' Tumor Staging Stage Criteria

Stage	Criteria
I	The tumor is limited to the kidney and has been completely resected. The tumor was not ruptured or biopsied prior to removal. There is no penetration of the renal capsule or involvement of renal sinus vessels.
II	The tumor extends beyond the capsule of the kidney but was completely resected with no evidence of tumor at or beyond the margins of resection. There is penetration of the renal capsule or invasion of the renal sinus vessels.
III	Gross or microscopic residual tumor remains postoperatively, including inoperable tumor, positive surgical margins, tumor spillage surfaces, regional lymph node metastases, positive peritoneal cytology, or transected tumor thrombus. The tumor was ruptured or biopsied prior to removal.
IV	Hematogenous metastases or lymph node metastases outside the abdomen (e.g., lung, liver, bone, brain).
V	Bilateral renal involvement is present at diagnosis, and each side may be considered to have a stage.

Image 9.16Wilms' Tumor Staging.

Дата добавления: 2014-10-15