Off-Clamp Laparoscopic Partial Nephrectomy for a Fat-Poor Angiomyolipoma Arising from the Renal Capsule: A Case Report

Renal function can be significantly preserved after nephron-sparing surgery by decreasing the intraoperative ischemic duration or by performing off-clamp surgery. We report the case of a 56-year-old woman diagnosed with a minimal-fat angiomyolipoma arising from the renal capsule, which was successfully treated by retroperitoneoscopic partial nephrectomy without hilar clamping. Computed tomography revealed a 16 × 13 mm homogenous lenticular mass protruding from the lateral aspect of the left kidney. On both T1- and T2-weighted magnetic resonance images, the mass exhibited homogenous low-signal intensity and well-defined margins. Laparoscopic magnification indicated that the exophytic tumor was attached to the renal cortex by a small peduncle. The tumor was resected completely with negative surgical margin. The estimated glomerular filtration rate after surgery was nearly equal to that before surgery. Off-clamp laparoscopic partial nephrectomy is a feasible surgical option to prevent ischemic renal damage in select patients presenting with small, exophytic, and peripheral renal masses.