OBJECTIVE: To report the diagnosis and treatment of a patient with a giant renal malformation tumor combined with vena cava tumor embolism, to discuss the treatment options, and to provide reference and guidance for the treatment of rare cases. METHODS: We summarized and analyzed the clinical data and treatment of a patient with a giant renal malformation tumor combined with vena cava tumor embolism, and reviewed the literature for analysis and discussion. RESULTS: Combining the medical history, physical examination and ancillary examination results, the patient was considered to have a clear diagnosis of renal malformation tumor combined with vena cava tumor embolism, and was discharged after radical laparoscopic left nephrectomy and open vena cava tumor embolism removal. Conclusion: Renal malformation tumor combined with renal vein and vena cava tumor embolus is a rare case in urology, and for special cases with huge tumors, radical laparoscopic nephrectomy with open tumor embolus removal is an optional procedure. It can minimize trauma and improve disease prognosis and patient’s quality of life while ensuring surgical safety. Keywords]: renal malformation tumor, vena cava tumor embolus, laparoscopic nephrectomy, vena cava embolus removal Renal malformation tumor, also known as renal vascular smooth muscle lipoma, is a benign tumor of the kidney. It is a benign tumor of the kidney, and its incidence has increased in recent years along with advances in diagnostic techniques. It is rare that renal malformation tumor is combined with tumor embolism, including renal vein tumor embolism and even vena cava tumor embolism. In this paper, we report the clinical information and treatment of a patient with renal giant mismatch tumor combined with vena cava tumor embolism, and analyze and discuss the case with the relevant literature. The patient, a 66-year-old female, was admitted to the hospital 3 months ago, and suddenly developed abdominal pain and vomiting when lifting a heavy object, accompanied by total carnitic hematuria, without vomiting blood or black stool. An ultrasound examination was performed in the emergency room, suggesting “left renal malformation tumor”; an MRI examination suggested an accumulation of fluid in the abdominal cavity and a large mass lesion in the left abdominal cavity, which originated from the left kidney. A bleeding left renal malformation tumor was considered. He was treated with hemostasis and blood transfusion, and the hematuria disappeared and the abdominal pain was relieved. 2 months ago, abdominal pain, vomiting and hematuria appeared again without any cause, and the abdominal pain and hematuria disappeared after super-selective interventional embolization of the left renal artery. This time, he was admitted to the hospital for follow-up. On examination, a large mass, about 15 cm in diameter, hard and without pressure pain, was palpable in the left upper abdomen, and the rest was not special. Auxiliary examination 1. Blood routine, biochemical and coagulation tests did not reveal any special abnormalities. Urine sediment microscopy: RBC 1-3/HP, WBC 18-22/HP. 2. Ultrasound of the urinary tract: left kidney giant malformation tumor, size about 16×15×12cm, occupying almost all of the kidney, only a small amount of normal kidney structure remains in the left kidney. 3.Enhanced CT of abdomen: left renal giant malformation tumor with fatty density filling defect in the left renal vein to the inferior vena cava, which was considered as tumor embolus. A small amount of fat density in the bladder, considering the possibility of tumor breaking through the renal calyces. 4.Urological MR: Giant malformation tumor of the left kidney with compression of the left kidney and mild hydronephrosis in the renal calyces. The abnormal signal in the left renal vein and inferior vena cava, with a high possibility of thrombosis. In this case, the diagnosis of giant renal malformation tumor was clear, the tumor had ruptured and bleeding, and selective arterial embolization had been performed. After careful review of the films and consultation with vascular surgery and cardiac surgery, we considered that the diagnosis of intraventricular tumor thrombus was clear, the upper edge of the tumor thrombus was at the level of the lower edge of the liver, and the composition was mainly fat. After considering the surgical skills of the surgeon, the consultation and the patient’s wishes, we decided to perform posterior laparoscopic radical left nephrectomy and open vena cava dissection for embolization. During the operation, the left nephrectomy was performed in the lateral position, and the posterior laparoscopic left nephrectomy was performed routinely in 3 trocar. The lower pole, dorsal side, ventral side and peripheral space of the kidney were freed successively, and the renal artery was found on the dorsal side of the kidney and then cut off with hem-o-lock clamp, and the upper pole of the kidney was freed and the ipsilateral adrenal gland was preserved. After satisfactory freeing of the left kidney, each trocar was withdrawn and the puncture incision was sutured. The left kidney specimen was removed from the left side of the rib cage by making a 15-cm long oblique incision, cutting the lateral peritoneum along the lateral aspect of the descending colon, severing the splenic colonic ligament, pushing the colon toward the midline, and continuing the complete freeing and removal of the left kidney specimen. After fully exposing the inferior vena cava and bilateral renal veins, probing the tumor embolus located in the inferior vena cava up to the level of the inferior hepatic margin, blocking the right renal vein and the distal and proximal ends of the inferior vena cava respectively with vascular blocking tape, longitudinally dissecting the inferior vena cava, completely removing the tumor embolus and sending it to pathology, confirming that no tumor embolus remained, suturing the vena cava incision twice in succession with vascular anastomoses, releasing the block, checking for no blood leakage, and ending the operation. Postoperative management The patient recovered well and was discharged on the 3rd day after surgery with semi-liquid diet, and the wound drainage was removed on the 5th day, and the wound stitches were removed on the 7th day. Postoperative pathological report: left renal vascular smooth muscle lipoma, size 20cm×20cm×8cm, with fat necrosis and multinucleated giant cell reaction. The kidney was atrophic and fibrotic with renal infarction. The tumor embolus was tumor tissue with the same nature as before. Discussion Renal malformation tumor is a benign tumor of the kidney, which generally progresses slowly and is limited, except for oligoastrocytic malformation tumor. The early diagnosis of renal malformation tumor depends on the positive manifestation of ultrasound and CT, such as ultrasound detecting a hyperechoic mass and CT showing a fatty density (-20~-100HU) mass in the kidney area. Patients with progressive disease often complain of palpable masses in the quadriplegia or even hematuria. At present, it is generally accepted that partial nephrectomy or selective arterial embolization should be performed in the early stage of the disease to prevent serious complications such as bleeding and abdominal pain caused by the enlargement of the tumor. In this case, the patient had a huge renal malformation tumor combined with inferior vena cava tumor embolism, and similar cases are rare. Renal tumor embolism has been reported in many cases, the most common being renal cancer embolism, but also renal pelvis tumor, adrenal tumor, Wilms tumor, and Ewing sarcoma combined with renal vein and vena cava embolism. The present case suggests that benign renal tumors of large size may also form renal vein and vena cava tumor emboli. For patients with large tumors, preoperative ultrasound, CT, and MR examinations are useful for screening the possibility of tumor emboli and selecting the appropriate treatment. Similar to the Mayo classification of renal cancer tumor embolus, renal tumor embolus can be classified into four grades according to the invasion distance of the embolus: grade I: the distal end of the embolus is less than 2 cm from the vena cava; grade II: the embolus enters the vena cava but the upper edge does not reach the level of the lower hepatic margin; grade III: the upper edge of the embolus exceeds the lower hepatic margin; grade IV: the embolus enters the right atrium through the mediastinum. Individualized treatment should be selected preoperatively or intraoperatively based on the grade. Martinez-Salamanca et al. [1] presented the largest case series of renal cancer with vena cava thrombosis to date. 1215 patients with renal cancer underwent radical nephrectomy and thrombus removal, of whom 585 had vena cava accessible thrombus. The median follow-up time was 24.7 months and the median survival was 33.8 months for the 1122 patients who were followed up, with 5-year survival rates of 43.2% (Mayo grade I for renal vein involvement only), 37% (Mayo grades II-III for inferior diaphragmatic vena cava involvement), and 22% (Mayo grade IV for superior diaphragmatic vena cava involvement), respectively, according to the distance of the thrombus invasion. As far as the choice of procedure is concerned, the classic procedure remains open nephrectomy with extracorporeal circulation for inferior vena cava embolization. Open radical nephrectomy with vena cava tumor embolization and vena cava dissection for embolization of large renal malformation tumors has been reported in a large number of cases. Since the 1990s, laparoscopic surgery has become rapidly popular and highly respected, along with the popularization of the concept of minimally invasive surgery and the innovation and advancement of lumpectomy techniques. A growing body of literature indicates that traditional open radical nephrectomy and partial nephrectomy can be and have been largely replaced by lumpectomy and lumpectomy. However, there are a limited number of clinical studies on the use of lumpectomy in cases of renal tumors combined with renal vein and vena cava aneurysm emboli. The tumor embolus Mayo classification was grade II-III in all cases, and no tumor recurrence was seen in five of the patients during a mean follow-up time of 16 months, suggesting a good prognosis. The authors concluded that this procedure proved to be technically safe and feasible, but a thorough preoperative assessment of the patient’s general condition and strict control of the surgical indications are required. Relative contraindications to surgery include oversized tumors (>8 cm in diameter), excessive BMI (>30), and low ECOG strength score (<2). It is necessary to choose the right time to convert to open, to free the kidney more safely, and to obtain the appropriate operating field and space. With the multidisciplinary support of vascular surgery and cardiac surgery, intraoperative application of ultrasound can be chosen to survey and locate the tumor embolus and remove it under direct vision, thus ensuring the safety of the operation. A case of lumpectomy for radical nephrectomy and open vena cava embolization for renal tumor. The perinephric space was freed by lumpectomy, the renal artery was dissected by clamping, and the vena cava was removed under direct vision after an 8-12 cm long incision between the 11 ribs was made to remove the tumor and the tumor embolus specimen together, and then the vena cava was repaired with continuous sutures. The average intraoperative blood loss was 517 ml (250-900 ml), the average operative time was 248 minutes (225-274 min), and the average postoperative hospital stay was 6.2 days (4-11 days), with no clear complications in the perioperative period. This suggests that lumpectomy-assisted radical nephrectomy with open vena cava embolization is a difficult but technically feasible procedure that can significantly reduce surgical trauma and improve prognosis. In this case, after considering the surgical skills of the surgeon, the consultation of cardiac surgery and vascular surgery, and the patient's wishes, the decision was made to perform posterior laparoscopic radical left nephrectomy and open vena cava dissection for embolization. The operation went smoothly. The diameter of the left renal tumor was about 20 cm, and the length of the tumor embolus in the vena cava was about 2.5 cm, and the operation took about 4.5 hours, with 400 ml of intraoperative bleeding and no blood transfusion. The postoperative hospital stay was 7 days. The patient recovered well, and no serious complications occurred during the perioperative period. The operator's experience is that even for the huge renal malformation tumor, the magnification effect of the lumpectomy can make the local structure of the huge renal malformation tumor more clearly and accurately displayed during the lumpectomy operation, which can facilitate the location and distribution of the lesion margin and blood vessels, making the operation more precise and detailed, reducing unnecessary injuries, and the incidence of complications such as intraoperative hemorrhage and organ damage will be much lower than that of open surgery. Open surgery. For patients, not only the length of the wound is shortened, but also the benefits and prognosis are better in terms of refinement and individual treatment. Looking ahead, with the continuous advancement of lumpectomy techniques and surgical instruments, more minimally invasive and novel procedures are becoming possible.Romero et al [13] reported the first case of fully lumpectomy operated intraventricular embolization of the vena cava.Martin et al. reported 14 cases of T3b renal tumor patients undergoing pure lumpectomy with radical nephrectomy and inferior vena cava embolization. They added an additional access at the umbilical level and used laparoscopic manipulation to push the vena cava embolus back into the renal vein before performing radical nephrectomy, thus eliminating the need for open vena cava dissection for embolization. Only one of the 14 patients reported developed pulmonary embolism on the fifth postoperative day, which improved after anticoagulation therapy. Abaza et al [15] reported five cases of robotic-assisted radical resection of renal tumors with inferior vena cava dissection for embolization. The entire procedure from blocking and dissection of the vena cava to removal of the tumor embolus was accomplished with the application of robotic-assisted lumpectomy. The average intraoperative blood loss was only 170 ml (50-400 ml), the average operative time was 327 minutes (240-411 min), and the average postoperative hospital stay was only 1.2 days, with no clear complications in the perioperative period. This undoubtedly demonstrates the great advantages of robotic-assisted lumpectomy, which can simplify the complex operations involved and facilitate and make possible a purely lumpectoscopic inferior vena cava dissection for embolization. Conclusion In this paper, we report a case of a large renal malformation tumor combined with vena cava tumor embolism, and similar cases are rare, suggesting that large benign renal tumors may also form renal vein and vena cava tumor embolism, and that preoperative examination and rational selection of treatment methods are needed. Laparoscopic radical left nephrectomy and open inferior vena cava dissection for embolization are the optional procedures. Laparoscopic surgery can provide better benefits and prognosis for patients in terms of refinement and individual treatment. With the further development of laparoscopic technology, especially robot-assisted laparoscopic technology, laparoscopic surgery for T3b-based renal tumors with tumor embolism invasion is the trend of urological surgery in the future.