INVESTIGATIVE UROLOGY

Laparoscopic Partial Nephrectomy for Renal Masses: Effect of Tumor Location
Venkatesh R, Weld K, Ames CD, Figenshau SR, Sundaram CP, Andriole GL, Clayman RV, Landman J
Division of Urology, Department of Surgery, Washington University School of Medicine, St. Louis, Missouri, USA
Urology. 2006; 67: 1169-74

• Objectives: To report our single institutional experience of laparoscopic partial nephrectomy (LPN) for enhancing renal masses and evaluate outcomes and histopathologic findings with respect to the location of the renal mass.
• Methods: A retrospective review of LPN for 123 renal masses completed by 7 urologists was performed. Of these lesions, 49 (40%) were exophytic, 19 (15.5%) endophytic, 47 (38%) mesophytic, and 8 (6.5%) were hilar. We defined exophytic as more than 60%, mesophytic as 40% to 60%, and endophytic as less than 40% of the renal mass protruding off the surface of the kidney on radiologic imaging studies. Hilar lesions were those located within 5 mm of the renal hilar structures, regardless of the surface characteristics.
• Results: The mean tumor size was 2.6 cm (range 1 to 9). Hilar vessel clamping was performed during 55 procedures (44.7%); the mean warm ischemia time was 27 minutes (range 12 to 52). On final histopathologic examination, 3 patients (2.5%) had positive tumor resection margins. Overall, 26 (20.6%) complications occurred. The complication rate was significantly less for patients who underwent LPN for an exophytic (10%) or a mesophytic (12.8%) mass than for those with an endophytic (47%) or a hilar (50%) mass. Histopathologic examination of the renal masses revealed malignant pathologic features in 86 (69%) and benign findings in 37 (31%). In our series, only 55% of exophytic tumors were malignant and, if malignant, were invariably low grade (96%).
• Conclusions: The complications of LPN and the malignancy rate of the renal lesions were related to the tumor location within the kidney.
  
  
• Editorial Comment
  The authors nicely demonstrate that the intrarenal tumor location has a significant impact on the complication rate during laparoscopic partial nephrectomy. The authors remembered us that the lesions close to the hilum are the most prone to surgical complications (50%). Also, it was reported that the upper pole tumors resulted in the greatest average blood loss and complication rate (25.8%).
  I would like to take the opportunity to remember those involved in upper pole resection that the vascular anatomy in this region, as related to the kidney collecting system, is the most complex (1). Of utmost importance is the fact that the posterior segmental artery itself was in close relationship to the upper infundibulum or to the junction of the pelvis with the upper calyx in 57.3% of the cases (1,2). Therefore, this artery is at great risk during incisions close to the hilum (less than 1 cm). Injury to the posterior segmental artery (retropelvic artery) will result in significant hemorrhage and may be associated with destruction of a large area of the remaining renal parenchyma. In some cases, the area supplied by the posterior segmental artery corresponds to approximately 50% of the functioning renal tissue in normal kidneys (3).

References
1. Sampaio F: Anatomical background for nephron-sparing surgery in renal cell carcinoma. J Urol. 1992; 147: 999-1005.
2. Sampaio F: Renal anatomy. Endourologic considerations. Urol Clin North Am. 2000; 27: 585-607.
3. Sampaio F, Schiavini JL, Favorito LA: Proportional analysis of the kidney arterial segments. Urol Res. 1993; 21:371-4.

Dr. Francisco Sampaio
Full-Professor and Chair, Urogenital Research Unit
State University of Rio de Janeiro
Rio de Janeiro, Brazil