CASE REPORT Urology Journal/Vol 19 No. 4/ July-August 2022/ pp. 339-342. [DOI:10.22037/uj.v19i.7042] Percutaneous Internal Drainage in Symptomatic Renal Parapelvic Cyst Refractory to Sclerotherapy: A Case Report Suyoung Park1, Jeong Ho Kim1*, Jung Han Hwang1, Ki Hyun Lee2, Sung Hyun Yu1 Percutaneous sclerotherapy is a safe and effective treatment for renal parapelvic cysts. However, if the cyst is in communication with the adjacent renal pelvocalyceal system, sclerotherapy is contraindicated and alternative treatment should be considered. Here, we report a case of a patient with a symptomatic renal parapelvic cyst that was treated using a novel technique involving percutaneous new tract formation between the cyst and renal pelvis. 1Department of Radiology, Gil Medical Center, Gachon University College of Medicine, Incheon, Republic of Korea. 2Department of Radiology, Hwasung DS Hospital, Hwasung, Republic of Korea. *Correspondence: Department of Radiology, Gil Medical Center, Gachon University College of Medicine, Incheon, 21565, Republic of Korea. Tel: +82 032 4603063, Fax: +82 032 4603065, E-mail: ho7ok7@gilhospital.com. Received October 2021& Accepted April 2022 INTRODUCTION Renal parapelvic cysts require treatment for complications such as hydronephrosis, infection, or pain(1). We report a patient with a parapelvic cyst treated with a novel method as percutaneous sclerotherapy was con- traindicated due to communication between the cyst and renal pelvocalyces. CASE REPORT A 68-year-old man with left flank pain visited our medical center. The patient had a medical history of hyperten- sion and cerebral infarction. Urinalysis results were normal. Computed tomography (CT) showed a 10-cm left renal parapelvic cyst and severe left hydronephrosis (Figure 1). Transurethral double-J stent insertion was performed; however, the hydronephrosis remained unresolved. As the renal parapelvic cyst may have resulted in hydronephrosis, which in turn caused the flank pain, percutaneous sclerotherapy was then performed. An 8.5-Fr catheter (Sungwon Medical, Cheongju, Korea) was inserted into the cyst. Communication between the cyst and renal pelvocalyces was absent on fluoroscopy and cone-beam CT after injection of contrast media, immediately after aspiration of 300 mL of clear fluid (Figure 2). Sclerotherapy was performed using 30 mL of 99.9% ethanol as the sclerosant. After 60 min, the ethanol was completely aspirated, and the catheter was retained. The amount of drainage through the catheter was higher than 2000 mL/day, which was maintained for 3 days. The creatinine level in the fluid was 37 mg/dL, suggesting the formation of a new communicating structure with the Figure 1. Contrast-enhanced axial (a) and coronal (b) CT images taken in the renal excretory phase show a large left parapelvic cyst (asterisk) and associated hydronephrosis. urinary tract. Tubography and cone-beam CT (Figure 3) indeed showed a communication between the cyst and renal calyx, which implied a contraindication for addition- al sclerotherapy. Alternatively, internal drainage of the cyst fluid into the renal pelvocalyx was planned. However, cannulation of the communicating tract was attempted, but failed. To overcome this issue, a new tract was created between the cyst and the renal pelvis. Ultrasonography- and fluoroscopy-guided puncture of the upper renal calyx was performed via the catheter route using a 21-gauge needle (Figure 4a). An 8.5-Fr catheter with additional sideholes was inserted through the tract with the tip in the renal pelvis (Figure 5). The catheter was maintained for 1 month to allow tract mat- uration and was removed after tract patency was con- firmed. The cyst and subsequent hydronephrosis were resolved at the 2-month follow-up (Figure 6a). 1-year follow-up noncontrast CT scan (Figure 6b) showed no evidence of any relapsed parapelvic cyst. The flank pain remained absent at an outpatient follow-up 6 months after the last CT scan. DISCUSSION This report describes a novel percutaneous method for the internal drainage of a renal parapelvic cyst. Percu- taneous sclerotherapy is a minimally invasive treatment with low recurrence rates for renal cysts(2,3). However, if the cyst is in communication with the renal pelvocal- yces, the use of a sclerosant may damage their endothe- lium, and alternative treatments should be considered. In our patient, sclerotherapy was performed with no ev- idence of communication between the cyst and pelvoc- alyces. However, communication between the cyst and the adjacent renal calyx subsequently appeared; thus, sclerotherapy could no longer be performed. The concept of draining a cyst into the urinary tract has been introduced as a method involving direct incision Figure 2. Fluoroscopy (a) and cone-beam CT (b) images taken during the first session of sclerotherapy show no contrast leakage out of the cyst. Figure 3. Both fluoroscopy (a) and cone-beam CT (b) images taken before the second session of sclerotherapy show communication (arrow) between the renal parapelvic cyst and adjacent renal upper polar calyx (asterisk). Percutaneous internal drainage for renal parapelvic cyst-Park et al. Vol 19 No 4 July-August 2022 340 Urology Journal/Vol 19 No. 3/ May-June 2022/ pp. 241-245. [DOI:10.22037/uj.v18i.7297] Figure 4. (a) Direct puncture of renal upper polar calyx was per- formed through the parapelvic cyst, and the tract was dilated using a balloon catheter (b). of the cyst wall through retrograde flexible ureterosco- py or antegrade nephroscopy(4-7). To mitigate any risk, accurate information about the surrounding structures must be obtained during cyst wall incision. In this sense, ultrasonography- and fluoroscopy-guided per- cutaneous approaches have the advantage of allowing visual access to the surrounding tissues during surgery. We report a patient with a renal parapelvic cyst that was not eligible for additional sclerotherapy session and was successfully treated with a novel procedure involving a tract formation between the cyst and the renal pelvis. Figure 5. (a) A pigtail catheter with additional sideholes is placed through the newly formed tract with the tip inside the renal pelvis, to keep the tract patent. (b) Diagram shows percutaneous new tract formation and pigtail catheter placement. The catheter passes through the cyst (white arrow) and the renal pelvic wall (black arrow), and its end is located in the renal pelvis (asterisk). Sideholes are marked as semicircles in the pigtail catheter. The procedure reported here could be considered as an effective alternative treatment option when percutane- ous sclerotherapy is not indicated. CONFLICT OF INTEREST No potential conflict of interest was reported by the au- thors. REFERENCES 1. Eissa A, El Sherbiny A, Martorana E, et al. Non-conservative management of simple renal cysts in adults: a comprehensive review of literature. Minerva Urol Nefrol. 2018;70:179- 192. 2. Bean WJ. Renal cysts: treatment with alcohol. Radiology. 1981;138:329-331. 3. Cho DS, Ahn HS, Kim SI, et al. Sclerotherapy of renal cysts using acetic acid: a comparison with ethanol sclerotherapy. Br J Radiol. 2008;81:946-949. 4. Luo Q, Zhang X, Chen H, et al. Treatment of renal parapelvic cysts with a flexible ureteroscope. Int Urol Nephrol. 2014;46:1903- 1908. 5. Zhao Q, Huang S, Li Q, et al. Treatment of Parapelvic Cyst by Internal Drainage Technology Using Ureteroscope and Holmium Laser. West Indian Med J. 2015;64:230-235. 6. Agarwal M, Agrawal MS, Mittal R, Sachan V. A randomized study of aspiration and sclerotherapy versus laparoscopic deroofing in management of symptomatic simple renal cysts. J Endourol. 2012;26:561-565. 7. Basiri A, Hosseini SR, Tousi VN, Sichani MM. Ureteroscopic management of symptomatic, simple parapelvic renal cyst. J Endourol. 2010;24:537-540. Percutaneous internal drainage for renal parapelvic cyst-Park et al. Case Report 341 Figure 6. Both 2-month (a) and 14-month (b) follow-up coronal CT images show resolved parapelvic cyst and hydronephrosis. Percutaneous internal drainage for renal parapelvic cyst-Park et al. Vol 19 No 4 July-August 2022 342