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Staging System for Wilms Tumor
I Tumor confined to kidney and completely resected. No
penetration of the renal capsule or involvement of renal
sinus vessels
II Tumor extends beyond kidney but completely resected. (a)
penetration of renal capsule (b) invasion of renal sinus
vessels
III Gross or microscopic residual remains postoperatively
(inoperable tumor, positive surgical margins, tumor spillage
either before or during surgery, regional lymph node
metastases, tumor is removed greater than one piece,
penetration through peritoneal surface)
IV Hematogenous or lymph node metastases outside abdomen
V Bilateral Wilms’ tumor at onset