Histogenesis Of Parapelvic Cysts And The Technique Of Internal Drainage With Retrograde Ureteroscope And Holmium Laser

Objective:Parapelvic cysts are non-genetic renal cystic diseases, which are found to be proximal to renal pelvis or renal pedicle, cysts arise as results of congenital dysplasia or acquired obstruction in kidney. Their incidence was reported up to 1-3% in all simple renal cysts. The terms parapelvic and peripelvic generally describe the location of cysts, and it originated from renal parenchyma or sinus renalis. Peripelvic cysts derive from renal sinus, while cysts originating from outside of renal sinus and intruding into sinus are called parapelvic cysts, that may originated from the renal parenchyma. Pyelogenic cysts can be misdiagnosised as parapelvic cysts in imaging examination when cysts intrude into renal sinus.Parapelvic cysts, Peripelvic cysts and pyelogenic cysts, these three kinds of cysts come from different origins of tissue, so the epithelial cells in the cyst wall are not the same types. They could derive from renal tubule, lymph vessel, blood vessel and even transitional epithelium. The origins of the cyst walls can be detected by correlating markers. CK18, D2-40 and CD34 have been known as specific marker of renal tubule, lymphatic epithelium and vascular endothelium respectively. Cystic fluid may be urinous, serous or lymphatic, which can be used to explore tissue origins.Since the special location in renal hilum and collecting system, parapelvic cysts can often cause compressing symptoms with its volume. Comparing to cysts of other location, parapelvic cysts are prone to cause obstruction, infection, hypertention, flank pain, hematuria and calculus. The treatment options of parapelvic cysts include open surgery, percutaneous aspiration with or without injection of sclerosants, percutaneous ablation, antegrade percutaneous nephroscopy unroofing or internal drainage, laparoscopic unroofing and internal drainage with retrograde ureteroscopy. The main purposes of the treatment are to drain the cyst fluid adequately and prevent the kidney, renal pelvis and renal hilus from compressing damage. Laparoscopic cyst unroofing has been the standard technique for treatment of parapelvic cysts. With the development of endourology, rigid or flexible ureteroscope could be a novel technique for parapelvic cysts in selected patients.Ureteroscope has been widely used in the diagosis and treatment of upper urinary tract diseases, including calculus, obstruction and tumors. Because the parapelvic cysts are closely related to renal pelvis and renal calyce; they are often separated only by a thin layer from collecting system, providing the anatomy basis for ureteroscope application. Currently, the successful application of ureteroscope unroofing for the treatment of symptomatic parapelvic cysts has been reported. However, few reports have a large sample and a long time follow-up to evaluate the safety and efficiency. The components of cyst fluid is not unidentified, whether the components of urine changes after internal drainage, whether the renal pelvis surgery could lead to obstruction, urinoma, infection, calculus and hematuresis, are need to be clarified further.The present study is to explore the histogenesis of parapelvic cysts using biochemical analysis of cystic fluid, morphology of capsule wall and immunohistochemistry. Our aim is to evaluate the efficacy and safety of internal drainage technique using ureteroscope and Holmium laser to treat renal parapelvic cysts by comparing with laparoscopic unroofing of parapelvic renal cysts. Feasibility and superiority of ureteroscope and its surgical indication and contraindication are also elucidated.Methods:1. Expression of CK18, D2-40 and CD34 in endothelial cells of parapelvic cysts using immunohistochemistry.2. Biochemical analysis of cystic fluid. About 2-5ml fluid was retracted during operation. Concentrations of sodium, potassium, chlorinum, urea nitrogen, creatinine, glucose and total protein were measured. Compare the concentration of substances in cyst fluid and plasma.3. Cyst fluid qualitative analysis. Adopt the automatic urine analyzer to have qualitative analysis of cyst fluid, and compare it with the routine urine test results.4. The patients were registered in Shandong Provincial Qianfoshan Hospital from 2006.8 to 2013.1.62 patients with parapelvic cyst were divided into two groups randomly. Group A received operation by ureteroscope with Holmium laser, while group B using laparoscopic technique.5. Ureteroscopy Group. F8/9.8 Wolf rigid ureteroscope was inserted into the renal pelvis retrogradely. Inside the ureteropelvic region, the cyst wall was generally found to be compressing the collecting system and was noted to be obstructing the urinary collecting system. Then, the cyst wall with obvious suppression mark observed by CT before operation was carved by 365 μm holmium laser. When the cyst was confirmed, the cut was expanded to remove the cyst wall about 1 cm diameter. Then, the cyst was connected with collective system. The cyst that the rigid ureteroscope could not reach was operated by flexible ureteroscope and 200μm holmium laser. The 5F double-J stent was placed with the proximal end coiled in the cyst cavity to drain the cystic fluid. Base on the observation of cyst by ureteroscope, there were two kinds of cysts. The first was shown as blue in ureteroscopy and easy to be separated with other parts of renal pelvis it could be carved by holmium laser directly. For the other kind of cyst, the cyst wall was relatively thick and besides the mark of suppression, it had the same color with other parts of renal pelvis, it is necessary to carefully cut the mucous membrane of renal pelvis, tissue under mucous membrane, and cyst wall step by step in the position without pulsation in order to avoid the damage on blood vessel and renal parenchyma.6. Laparoscopy Group. The retroperitoneal route was the preferred access in all patients. The procedure was usually performed with 3ports. Parapelvic cysts were resected entirely, or resected circlely near renal parenchyma if the cysts could not be removed entirely.7. Curative effect and follow up. The first time of follow-up was the third mouth after operation. Record the postoperative and follow-up results of each group, including symptoms improvement, laboratory examination and imaging examination results, and compare them to preoperative conditions, evaluate the safety and efficacy of operation method of ureteroscopy group. Compare the two groups, including:the operation time, amount of intraoperative bleeding, pain score, postoperative activity time, postoperative hospital stay, postoperative complications, recurrence, etc. Radiographic success was defined as no recurrence of the cyst on the most recent imaging, partial success indicated a reduction in cyst volume of at least 50%.Results:1. The lining wall of parapelvic cysts and lymphatic cysts were simple epithelium, but pyelogenic cysts were transitional epithelium. The epithelium in parapelvic cysts expresssed CK18 but not D2-40 and CD34 (P<0.05). The same results were found in pyelogenic cyst. The epithelium in lymphatic cysts expresssed D2-40 but not CK18 and CD342. Cyst fluid biochemical parameters:Urea nitrogen and glucose level in cystic fluid were higher than in plasma, and total protein was lower in cystic fluid significantly(P<0.05).3. Cyst fluid qualitative analysis parameters:glucose+～++, protein+～+++,were higher than in urine(P<0.05).4. Ureteroscopy Group.31 cases were treated successfully (93.9%),2 cases failed to be operated by ureteroscope due to the narrow ureter and was operated by laparoscope instead.15 cases adopt electronic flexible ureteroscope, but 6 cases’suppression of cyst on the renal pelvis cannot be determined. The mean operation time was 56.2 min (range 30-101min). The mean time of handling the cyst was 19.1 min (range 8-31 min). The mean estimated blood loss was 26.8 ml (range 10-56ml). During the operation, there was no massive haemorrhage, no damage on the organ around or ureter and other serious complications.3 cases suffered obvious urinary irritation, were prescribed M receptor blockers. There were no serious hematuresis, urinary extravasation, obvious infection, thrombus after operation.24 cases out of 27 who suffer with abdominal or flank pain were cured or relieved. The routine urine test, blood routine test and biochemical test were assessed during the period of follow-up and are all normal. The average follow-up period was 37 months (range 6-72). CT and type-B ultrasonic were used for radiographic follow up. No urinary calculus or tumor were found. In 27 of 31 patients, the cyst could not be found and the kidney was recovered to its normal shape. The diameter of cyst was reduced for more than 50% compared with that before operation in 3 cases, the total effective rate is 96.8%.5. Laparoscopy Group.28 cases were treated successful cases (96.6%),1 case altered to open surgery in 29 cases. The mean operation time was 96.5 min (range 71-135min). The mean time of handling the cyst was 26.8 min (range 15-41 min). The mean estimated blood loss was 68.6 ml (range 35-430ml). No major complication was encountered. Leakage of urine was found in 2 cases postoperatively (the corresponding pathological pattern is pyelogenic cysts). The average follow-up period was 37 months (range 6-72). 22 cases out of 26 who suffer with abdominal or flank pain were cured or relieved. In 18 of 28 patients, the cyst could not be found and the kidney was recovered to its normal shape. The diameter of cyst was reduced for more than 50% compared with that before operation in 8 cases, the total effective rate is 92.9%.6. Data comparison and analysis:Compare the achievement ratio of operation, follow-up recurrence rates and perioperative indexes of two groups, including:the operation time, amount of intraoperative bleeding, pain score, out-of-bed time, postoperative hospital stay time, postoperative complications. There was no significant difference between ureteroscopy and retroperitoneoscopy group in the rate of operational success, symptom improvement and total utility in imaging(P>0.05).The non-recurrence rate in ureteroscope group was 87.1%(27/31), while that of retroperitoneoscopy group is 64.3%(18/28), there was significant difference between the two groups (P<0.05). The operative complications, operative time, the treatment time of cyst, amount of intraoperative bleeding, pain score, out-of-bed time, postoperative hospital stay time of ureteroscopy group were better than those of the retroperitoneoscopy group (P<0.05).Conclusions:1. CK18 expressed in endothelial cells of parapelvic cysts, indicated that parapelvic cysts derived from renal tubule.2. Biochemical parameters in cystic fluid indicated that it was urine of different concentration or different gradient, which indirectly showed that parapelvic cysts derived from renal tubule.3. Internal drainage technique using ureteroscope and Holmium laser was using natural passage, so this treatment would have better curative effect, minor trauma, quick recovery and few complications in selected cases, more fit with human body physiology.4. Compared with retroperitoneoscopy, ureteroscope treatment had better curative effect in imaging examinations, fewer complications and more extensive indications so it could be suitable for totally inner kidney’s parapelvic cysts and pyelogenic cysts.5.Rigid ureteroscope was more suitable to treat parapelvic cysts than flexible ureteroscope. Parapelvic cysts were classified into two types under the direct observation then they were needed different strategies to cut open.Significance:1. To clarify that parapelvic cysts derived from renal tubule and provide theoretical basis for internal drainage technique.2. Internal drainage technique is safe and efficient to treat parapelvic cysts with retrograde ureteroscope and holmium laser, the technique is suitable for totally inner parapelvic cysts and pyelogenic cysts.It is superior to laparoscopic surgery, and become a new kind of minimally invasive surgery.3. Internal drainage technique could be performed in most hospitals, and provides a new operative treatment option.