The National Wilms' Tumor Study (NWTS) developed its V (5) staging system for patients with nephroblastoma.
|
Stage |
Criteria |
|
I |
limited to kidney completely excised, with margins free surface capsule of kidney intact (not penetrated by tumor) tumor not biopsied before nephrectomy (except by FNA) tumor not ruptured; no spillage no involvement of vessels of the renal sinus |
|
II |
extends beyond the kidney to involve regional, peri-renal soft tissue and blood vessels surface capsule of kidney penetrated by tumor completely resected, with margins free tumor biopsied (other than FNA) tumor ruptured with local spillage limited to flank invasion of renal sinus vessels or renal vein |
|
III |
tumor extends beyond the kidney but limited to the abdomen; includes extension to regional lymph nodes and peritoneal implants may not be completely excised (residual tumor) tumor ruptured with spillage into the peritoneal cavity |
|
IV |
distant metastases to liver, lung, bone and/or brain metastases to lymph nodes outside of the abdomen |
|
V |
bilateral tumors |
For bilateral tumors, the stage for each side should be determined, with the higher of the two designated as a numerical Substage.
Notes:
(1) Evaluation of renal capsule is important for separation of Stage I from Stage II tumors. Sections taken perpendicular to the capsule at points of tumor protrusion should be taken. If the tumor extends into a tissue plane that can be seen laterally to merge with perirenal fat, then the capsule is considered penetrated even if a secondary fibrous pseudocapsule is present. Occasionally Wilms' tumors may contain fat, and this should not be confused with the perirenal fat.
(2) Evaluation of the renal sinus is important to identify Stage II disease. This is the region where pelvicalyceal structures and vessels exit the hilum of the kidney, together with the adipose tissue adjacent to the medulla or nonencapsulated renal cortex.
(3) Retraction of the renal vein about an intravascular thrombus may cause a vascular margin to appear positive (false positive).
(4) Documentation of any spillage and its extent should be recorded in the operative report.
(5) Artifactual spread of tumor while sectioning the tumor is common. The specimen should be carefully inked before sectioning and any gross contamination documented.
(6) Direct extension from the right kidney into the liver may qualify for Stage II rather than Stage III.
Specialty: Hematology Oncology, Surgery, general, Nephrology
ICD-10: ,
