Keywords:
Neoplasia, Diagnostic procedure, Contrast agent-intravenous, CT, Kidney
Authors:
A. Tsili, A. Goussia, A. Ntorkou, A. Ntoulia, D. Giannakis, L. G. Astrakas, N. Sofikitis, V. Malamou-Mitsi, M. Argyropoulou; Ioannina/GR
DOI:
10.1594/ecr2013/C-0826
Purpose
Renal cell carcinoma (RCC) represents the commonest primary malignancy of the kidney,
accounting for about 2% of adult malignancies [1,2].
The American Cancer Society estimates that in 2012 there will be 64,770 new cases of renal cancer,
including 92% RCCs,
with an estimated 13,570 deaths due to this disease [3].
With the wide-spread use of cross-sectional imaging studies as many as half of RCCs are found incidentally,
usually diagnosed at an early stage.
This may allow a more limited surgical resection of the neoplasms,
such as laparoscopic or nephron-sparing partial nephrectomy [1].
The Tumor-Node-Metastasis (TNM) classification system defines advanced stage RCC within Gerota’s fascia as T3 (Table 1) [4].
According to the 2010 American Joint Committee on Cancer,
RCCs with extension into the renal vein or its segmental branches and invasion of the perinephric (PN) fat and/or renal sinus (RS) fat are all staged as T3a tumors.
Among the differences of the new TNM staging system when compared to the previous editions was to include invasion of the renal sinus fat and/or perinephric fat in T3a stage [4].
Table 1.
New TMN staging for renal cell carcinoma (Ref.
4).
Classification
|
Description
|
Tx
T0
T1
T1a
T1b
T2
T2a
T2b
T3
T3a
T3b
T3c
T4
Nx
N0
N1
M0
M1
|
Primary tumor cannot be assessed
No evidence of primary tumor
Tumor < 7 cm in greatest dimension,
limited to kidney
Tumor < 4 cm in greatest dimension,
limited to kidney
Tumor > 4 cm but < 7 cm in greatest dimension,
limited to kidney
Tumor > 7 cm in greatest dimension,
limited to kidney
Tumor > 7 cm but < 10 cm in greatest dimension,
limited to kidney
Tumor > 10 cm in greatest dimension,
limited to kidney
Tumor extends into major veins or perinephric tissues but not into the ipsilateral adrenal gland and not beyond Gerota fascia
Tumor grossly extends into the renal vein or its segmental branches,
or tumor invades perirenal and/or renal sinus fat but not beyond Gerota’s fascia
Tumor grossly extends into the vena cava below the diaphragm
Tumor grossly extends into the vena cava above the diaphragm or invades the wall of the vena cava
Tumor invades beyond Gerota’s fascia (including contiguous extension into the ipsilateral adrenal gland)
Regional nodes cannot be assessed
No regional lymph nodes metastases
Metastases in regional lymph node(s)
No distant metastases
Distant metastases
|
Several reports have highlighted that RCCs invading the perinephric fat and/or the renal sinus fat are associated with an unfavorable prognosis [8-14].
Infiltration of the perirenal fat tissue should also modify surgical approach from conservative to radical nephrectomy [1,2].
CT remains the most effective cross-sectional imaging modality for the detection and staging of RCC,
with a staging accuracy up to 91% [1,2,15-28].
Advances in multidetector CT technology have greatly improved the diagnostic performance of the technique in patients with renal malignancies [1,2,18-28].
However,
spread of RCC into the perirenal fat and differentiation between T1/T2 and T3a stages based on CT findings,
is not always feasible [1,2,15,16].
As to our knowledge,
there are a few published reports in the English-language literature on the accuracy of multidetector CT in diagnosing perirenal fat invasion in patients with RCC and no reports on the diagnostic performance of the technique in evaluating renal sinus fat infiltration.
The purpose of this study was to assess the accuracy of multidetector CT in the diagnosis of perinephric and/or renal sinus fat invasion in patients with RCC,
with reference to the CT findings predictive for the diagnosis of invasion.