Introduction: Centrally placed completely endophytic renal tumors pose a technical challenge to the surgeons. Identifying the tumor-kidney interface is crucial in partial nephrectomy. Anterior versus posterior approach requires tumor location assessment. We describe a case of 60-year-old female with complex left renal mass which posed technical difficulty in front of us. Methods: 60-year female was planned for left robotic partial nephrectomy for her left sided biopsy proven clear cell Renal cell carcinoma. She underwent right robotic partial nephrectomy. Left renal tumor was completely endophytic and adjacent to a renal cyst (Nephrometry Score 10a). After completely flipping the kidney, we used the intraoperative ultrasound followed by the technique of circular nephrotomy to identify renal tumor pseudocapsule (tumor-kidney interface) and the adjacent simple renal cyst. Results: We were able to enucleate the tumor and perform cyst decortication. No intra-operative complication occurred. Patient was discharged on POD1. Post operative creatinine was 1.23 mg/dl (Pre-op 1.1). Total operative time was 132 minutes. Warm ischemia time was 20 minutes. Final histology was Clear cell RCC, Margins were negative. Conclusions: Use of circular nephrotomy in select cases can allow surgeon to identify the resection plane (tumor pseudo-capsule) and complete the partial nephrectomy without complications. Adequate exposure to access the resection plane is the key principle. Use of ultrasound to determine “plane of attack” (having the shortest distance to tumor from surface) is our preferred approach. SOURCE OF Funding: None
