36 Kidney
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SUMMARY OF CHANGES
• T1 lesions have been divided into T1a and T1b.
• T1a is defined as tumors 4 cm or less in greatest dimension, limited to the kidney.
• T1b is defined as tumors greater than 4 cm but not more than 7 cm in greatest dimension, limited to the kidney.
C64.9 Kidney
INTRODUCTION
Cancers of the kidney are relatively rare, accounting for less than 3% of all malig- nancies. Nearly all malignant tumors are carcinomas arising from the renal tubular epithelium or, less frequently, from the renal pelvis (see Chapter 37).
These tumors are more common in males. Pain and hematuria are usually the presenting features, but a majority of kidney tumors are not being detected inci- dentally in asymptomatic individuals. These carcinomas have a tendency to extend into the renal vein and even into the vena cava. Staging depends on the size of the primary tumor, invasion of the adjacent structures, and vascular extension.
Since publication of the Fifth Edition of the AJCC Cancer Staging Manual, the evidence has become compelling that the T1 category should be subdivided into stages T1a and T1b, the former being tumors of 4 cm or less and the latter being tumors greater than 4 cm to 7 cm. The rationale is twofold: (1) the recur- rence of survival difference between the two and (2) the current practice of applying partial nephrectomy for solitary tumors 4 cm or less in diameter. In the case of partial nephrectomy for tumors <4cm in diameter, evidence suggests that survival outcomes are equivalent to outcomes with radical nephrectomy.
ANATOMY
Primary Site. Encased by a fibrous capsule and surrounded by perirenal fat, the kidney consists of the cortex (glomeruli, convoluted tubules) and the medulla (Henle’s loops, pyramids of converging tubules). Each papilla opens into the minor calices; these in turn unite in the major calices and drain into the renal pelvis. At the hilus are the pelvis, ureter, and renal artery and vein.
Gerota’s fascia overlies the psoas and quadratus lumborum. The anatomic sites and subsites of the kidney are illustrated in Figure 36.1.
Regional Lymph Nodes. The regional lymph nodes, illustrated in Figure 36.2, are:
Renal hilar Paracaval
FIGURE 36.1. Anatomical sites and subsites of the kidney.
C77.2
FIGURE 36.2. Regional lymph nodes of the kidney.
Aortic (para-aortic, periaortic, lateral aortic) Retroperitoneal, NOS
Metastatic Sites. Common metastatic sites include bone, liver, lung, brain, and distant lymph nodes.
DEFINITIONS Primary Tumor (T)
TX Primary tumor cannot be assessed T0 No evidence of primary tumor
T1 Tumor 7 cm or less in greatest dimension, limited to the kidney T1a Tumor 4 cm or less in greatest dimension, limited to the kidney (Figure
36.3)
T1b Tumor more than 4 cm but not more than 7 cm in greatest dimension, limited to the kidney (Figure 36.4)
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£4 cm T1a
FIGURE 36.3. T1a: tumor 4 cm or less in greatest dimension, limited to the kidney.
>4–£7 cm T1b
FIGURE 36.4. T1b: tumor more than 4 cm but not more than 7 cm in greatest dimension, limited to the kidney.
T2 Tumor more than 7 cm in greatest dimension, limited to the kidney (Figure 36.5)
T3 Tumor extends into major veins or invades adrenal gland or perinephric tissues but not beyond Gerota’s fascia
T3a Tumor directly invades adrenal gland or perirenal and/or renal sinus fat but not beyond Gerota’s fascia (Figure 36.6)
FIGURE 36.5. T2: tumor more than 7 cm in greatest dimension, limited to the kidney.
T3a T3a
Perinephric fat
Gerota fascia Adrenal gland
FIGURE 36.6. Two views of T3a, defined as tumor directly invades adrenal gland (right) or perirenal and/or renal sinus fat (left) but not beyond Gerota’s fascia.
T3b Tumor grossly extends into the renal vein or its segmental (muscle- containing) branches, or vena cava below the diaphragm (Figure 36.7) T3c Tumor grossly extends into vena cava above diaphragm or invades the
wall of the vena cava (Figure 36.8)
T4 Tumor invades beyond Gerota’s fascia (Figure 36.9) Regional Lymph Nodes (N)
NX Regional lymph nodes cannot be assessed N0 No regional lymph node metastases
N1 Metastasis in a single regional lymph node (Figure 36.10)
N2 Metastasis in more than one regional lymph node (Figures 36.10, 36.11) Distant Metastasis (M)
MX Distant metastasis cannot be assessed M0 No distant metastasis
M1 Distant metastasis
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T3b
FIGURE 36.7. T3b: tumor grossly extends into the renal vein or its segmental (muscle-containing) branches, or vena cava below the diaphragm.
T3c
FIGURE 36.8. T3c: tumor grossly extends into vena cava above diaphragm or invades the wall of the vena cava.
Perinephric fat Gerota fascia
N1 N2
FIGURE 36.10. N1, on the left, is defined as metastasis in a single regional lymph node. N2, on the right, is defined as metastasis in more than one regional lymph node.
N2
FIGURE 36.11. N2: Metastasis in more than one regional lymph node.
STAGE GROUPING
I T1 N0 M0
II T2 N0 M0
III T1 N1 M0
T2 N1 M0
T3 N0 M0
T3 N1 M0
T3a N0 M0
T3a N1 M0
T3b N0 M0
T3b N1 M0
T3c N0 M0
T3c N1 M0
IV T4 N0 M0
T4 N1 M0
Any T N2 M0
Any T Any N M1
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