Renal masses herniating into the hilum: technical considerations of the "ball-valve phenomenon" during nephron-sparing surgery

Abstract

Objectives: To describe our technique to recognize and resect renal tumors "ball-valving" into the sinus. Partial nephrectomy (PN) offers a functional advantage over radical nephrectomy for many cases of localized renal cell carcinoma. However, PN is underutilized particularly in anatomically challenging cases. Often unrecognized is the tendency for central renal tumors to herniate into the renal sinus.

Methods: From our prospective kidney cancer database, we identified 36 patients who underwent open, laparoscopic, or robotic PN for solitary localized renal cell carcinoma herniating into the renal sinus.

Results: Axial and reformatted radiographs were reviewed for all renal hilar lesions. Intraoperative techniques include hilar dissection, establishment of a sinus plane allowing tumor and parenchymal retraction, reduction of the tumor out of the sinus, resection, and repair. Mean preoperative lesion size was 3.8 cm. Indications for PN included 15 of 36 (42%) absolute, 13 of 36 (36%) relative, and 2 of 36 (6%) reoperative PN. No procedure was converted to radical nephrectomy. Of the 36 PN, 5 (14%) were performed using a minimally invasive approach and no minimally invasive surgery procedures were converted to open. No patient required renal replacement.

Conclusions: Recognition of the tendency for hilar masses to herniate or "ball-valve" into the renal sinus is essential for effective PN of central tumors. By using our technique, we have demonstrated success in nephron-sparing surgery with minimal intraoperative complications and favorable postoperative outcomes in patients with central tumors herniating into the renal sinus.

Figure 1

Axial cut of a computed tomography scan of a patient with bilateral renal masses. The left mass arises from the anterior aspect of the kidney and herniates into the renal sinus, illustrating the “ball valve” phenomenon.

Figure 2

Illustration summarizes the salient points of the technique to first reduce and then resect “ball-valving” tumors that herniate into the renal sinus. Intra-operative ultrasound is utilized to assess the depth and width of the tumor to assist with the planned resection. The plane between the tumor and the renal sinus fat is developed; the tumor is reduced; and the resulting space is packed tightly with a hemostatic agent such as Fibrillar (Ethicon, Somerville, NJ). The hilar vessels are then clamped, and the tumor is excised sharply off of the originating parenchyma. Fibrillar provides the surgeon with a topographical landmark for the medial boundary of the dissection and prevents inadvertent entry into the hilar structures.

Figure 3

Panel (A): Axial cut from a contrast-enhanced CT scan of a 64 year-old male with a solitary left kidney and a history of multiple prior abdominal surgeries. The arrow indicates the direction of rotation required to reduce the herniated tumor from the renal sinus during partial nephrectomy. Panel (B): Intra-operative photograph following tumor resection. The renal pelvis (*), infundibulum, and calyces are visible after the herniated tumor is reduced and resected from the sinus.