Enucleation/partial nephrectomy for large mixed epithelial stromal tumor and herniating into the pelvicalyceal system

OBJECTIVES: Mixed Epithelial and Stromal Tumor of the kidney is an adult renal neoplasm. It is mostly benign in nature. Typically it is composed of a mixture of epithelial and mesenchymal components. We hereby report on the feasibility of performing partial nephrectomy/enucleation for Huge Mixed Epithelial Stromal Tumor of the kidney without sacrificing the involved renal unit even in the tumors herniating into the collecting system. METHODS: Two female patients on long term hormonal therapy developed large enhancing multiloculated and septated renal masses. Kidney mass size was 18.5 cms in one patient and 11.5 in the second. In one patient, the mass was herniating into the collecting system. Both patients had enucleation/partial nephrectomy. RESULTS: Enucleation and partial nephrectomy were successfully performed in both patients. In the patient with the mass herniating into the collecting system, the horns of the mass herniating into the collecting system were easily enucleated with repair of the collecting system and salvage of the involved renal unit. Post op pathology revealed MEST in both patients. There were no intraoperative or postoperative complications. CONCLUSIONS: Enucleation and partial nephrectomy for huge MEST is feasible. Mixed Epithelial Stromal Tumor herniating into the pelvicalyceal system may not warrant nephroureterectomy as previously reported.