Retroperitoneal laparoscopic partial nephrectomy for treatment of metanephric adenoma (Report of 6 cases)

Abstract

Objectives: To investigate the clinical and pathological features of metanephric adenoma (MA) and the clinical outcome after retroperitoneal laparoscopic nephron-sparing surgery.

Methods: Six out of 183 partial nephrectomies performed during January 2009 to August 2014 were confirmed to be MA confirmed by postoperative pathological study. Perioperative parameters of the six patients were then retrospectively collected, analyzed and compared with current literature, including warm ischemia time (WIT), total operation time, estimated blood loss (EBL), positive surgical margin (PSM), and complications. Surgical and oncological outcome of all six patients were evaluated based on a mean follow up of 17 months (5-48 months).

Results: Tumors in all six cases were all successfully removed by partial nephrectomy. Mean WIT was 24.7 min (19-35 min). Mean operation time was 103.6 min (82-147 min). Mean EBL was 53.5 ml (20-85 ml). No conversion, transfusion or other major complication were observed in all six cases. Postoperative pathology confirmed negative surgical margin in all six cases. During a mean of 17 month follow up (5-48 months), no local recurrence or metastasis were found in all six cases.

Conclusion: MA is a rare benign primary kidney epithelial cancer, which could hardly be differentiated from renal malignancies based on preoperative imaging. Our data suggested that retroperitoneal laparoscopic partial nephrectomy can be used for surgical treatment of MA, in terms of tumor control and preservation of renal function.

Keywords: Laparoscopic partial nephrectomy; Metanephric adenoma; Retroperitoneal.

Fig. 1

Preoperative CT scan. a Non-contrast CT scan results indicated that there was soft tissue density shadows in the lower-middle portion of the right kidney, with a clear boundary, a size of 4.2 × 3.8 cm and a CT value of 30–36 HU. b, c The density is uniform, and the enhancement degree of the tumor was significantly lower than that of the surrounding normal renal parenchyma

Fig. 2

Trocar configuration for retroperitoneal laparoscopic partial nephrectomy

Fig. 3

Pathological study. a tumor cross-section. b, c cells analyzed under microscopy showed the same size, with a relatively small volume, adenoid gland shape, small tubular arrangement, unclear nucleoli, no nucleus fission, and a loose and bright mesenchyme. (magnification: b × 4 objective; c × 10 objective)

Fig. 4

CT scan results of 4 months follow-up after surgery, a preoperative CT scan; b 4 month postoperative scan