Reliability of CT finding of the pararenal muscle invasion in renal cell carcinoma

Exact delineation of the local extension of renal cell carcinoma is essential for correct preoperative staging, planning of surgical approach, and prognostication. Recently, there have appeared many article on the role of CT in staging renal cell carcinoma. However, little information is available regarding the accuracy of CT in determining the spread of renal cell carcinoma to adjacent muscles. Authors retrospectively reviewed and analyzed CT scans of 34 patients with confirmed renal cell carcinoma to determine the accuracy of the diagnosis of renal cell carcinoma invasion of the perirenal muscles. 1. Obliteration of the fat planes between renal tumor and adjacent muscles or the diaphragmatic crura was noted in 22 patients (64.7%). There was, however, no actual neoplastic invasion of adjacent muscles, except in one patient who had nonspecific inflammation. 2. In the 22 patients with obliterated fat planes, nine showed ill-defined, irregular interface. Two of these nine patients had an obtuse angle between renal mass and adjacent muscles without evidence of invasion. 3. Our study indicates that the obliteration of the fat plane is not reliable sign of muscle invasion