A novel technique for creating solid renal pseudotumors and renal vein-inferior vena caval pseudothrombus in a porcine and cadaveric model

Purpose: We developed a simple means to replicate kidney tumors in an animal and cadaver model that could be used to create pseudotumors of different sizes and locations for use in surgical training. Materials and Methods: Various substances were injected ex vivo into the parenchyma of porcine kidneys to identify an optimal pseudotumor model. Renal pseudotumors were created percutaneously and endoscopically using 8 live pigs and a human cadaver model. A renal vein pseudothrombus porcine model was also created by injecting pseudothrombus material into the renal vein after renal hilar clamping. Procedures performed on pseudotumors included robotic partial nephrectomy, percutaneous biopsy and robotic nephrectomy with renal vein thrombectomy. All specimens were analyzed after resection. Results: The most ideal pseudotumor models were created from a mixture of gelatin, Metamucil (R) and methylene blue (metagel) or from Kromopan (R) hydrocolloid. We created 33 tumors 0.5 to 3.5 cm in size (mean 2.8). All tumors were a solid palpable mass on gross examination and ultrasonography revealed clearly visible hyperechoic lesions in 30 of 33. A renal vein tumor pseudothrombus model was successfully created in 3 pigs. We successfully performed robotic excision of pseudotumors, including partial nephrectomy for 16 and radical nephrectomy with renal vein thrombectomy for 3. Percutaneous needle core biopsy under ultrasound guidance was also successfully performed. Conclusions: We describe what is to our knowledge a novel technique of creating solid renal tumors and tumor thrombi that can be used for training in minimally invasive kidney surgery.