Table 3

SIOP WT 2001 staging criteria for renal tumours of childhood

Stage I

The tumour is limited to kidney or surrounded with a fibrous (pseudo)capsule if outside of the normal contours of the kidney. The renal capsule or pseudocapsule may be infiltrated by the tumour but it does not reach the outer surface.

The tumour may be protruding (“bulging”) into the pelvic system and “dipping” into the ureter but it is not infiltrating their walls.

The vessels or the soft tissues of the renal sinus are not involved.

Intrarenal vessel involvement may be present.

Fine needle aspiration or percutaneous core needle (“tru-cut”) biopsy does not upstage the tumour but the size of the needle gauge should be mentioned to the pathologist.
The presence of necrotic tumour or chemotherapy-induced change in the renal sinus and/or within the perirenal fat should not be regarded as a reason for upstaging a tumour providing it is completely excised and does not reach the resection margins.
Stage II

a) Viable tumour penetrates through the renal capsule and/or fibrous pseudocapsule into perirenal fat but is completely resected (resection margins “clear”).

b) Viable tumour infiltrates the soft tissues of the renal sinus.

c) Viable tumour infiltrates blood and lymphatic vessels of the renal sinus or in the perirenal tissue but it is completely resected.

d) Viable tumour infiltrates the renal pelvic or ureter's wall.

e) Viable tumour infiltrates adjacent organs or vena cava but is completely resected.

Stage III

Viable or non-viable tumour extends beyond resection margins.

Any abdominal lymph nodes are involved.

Tumour rupture before or intraoperatively (irrespective of other criteria for staging).

The tumour has penetrated through the peritoneal surface.

Tumour implants are found on the peritoneal surface.

The tumour thrombi present at resection margins of vessels or ureter, are trans-sected or removed piecemeal by surgeon.

The tumour has been surgically biopsied (wedge biopsy) prior to preoperative chemotherapy or surgery.

Note: The presence of necrotic tumour or chemotherapy-induced changes in a lymph node or at the resection margins is regarded as proof of previous tumour with microscopic residue and therefore the tumour is assigned stage III (because of the possibility that some viable tumour is left behind in the adjacent lymph node or beyond resection margins).
Stage IV
Haematogenous metastases (lung, liver, bone, brain, etc) or lymph node metastases outside the abdomino-pelvic region.
Stage V
Bilateral renal tumours at diagnosis. Each side should be sub-staged according to the above criteria.