Conservative and Radiological Management of Simple Renal Cysts: a Comprehensive Review BJUIBJU INTERNATIONAL Andreas Skolarikos , M

Conservative and radiological management of simple renal cysts: a comprehensive review BJUIBJU INTERNATIONAL Andreas Skolarikos , M. Pilar Laguna * and Jean J.M.C.H. de la Rosette * Athens Medical School, 2nd Department of Urology, Sismanoglio Hospital, Athens, Greece, and * Academic Medical Center University of Amsterdam, Department of Urology, Amsterdam, The Netherlands Accepted for publication 9 September 2011

To review the conservative and radiological What ’s known on the subject? and What does the study add? management of simple renal cysts a Simple renal cysts are a common entity, which may need observation and follow-up or systematic literature review was performed. treatment. Simple renal cysts are commonly found in the adult population. Increasing age is The study, for the fi rst time, systematically reviews the indications for follow-up or highly associated with its incidence. When radiological treatment of simple renal cysts. they remain asymptomatic they require neither treatment nor follow-up. When the shape of the cyst is slightly irregular ultimate technique and agent remain to be when asymptomatic. Radiological follow-up is mandatory to exclude clarifi ed. High rates of cyst disappearance intervention with the use of sclerosants malignant progression. Symptomatic cysts and long-lasting cyst volume reduction needs further evaluation and comparison require intervention. Ultrasound or have been reported with the use of various with other treatment methods. computed tomography guidance have been sclerosants. Ethanol in high concentrations effectively used for cyst puncture. However, and multiple injections is more commonly simple fl uid aspiration is ineffective leading used with new agents showing similar KEYWORDS to cyst recurrence. Aspiration should be effi cacy and better complication profi le. accompanied with the injection of a Studies comparing radiological intervention simple renal cyst , natural history , sclerosing agent to destroy renal cyst to surgical excision are lacking. Simple conservative treatment , radiological epithelium. Several issues such as the renal cysts may not require treatment intervention

INTRODUCTION creatinine, smoking, male gender, ‘ radiological treatment ’ , ‘ aspiration ’ , hypertension and age. However, given ‘ sclerotherapy ’ , ‘ sclerosants ’ and ‘ sclerosing Renal cysts are acquired lesions of the the retrospective nature of the reported agent ’ in the Medline, Embase and PubMed kidney that more commonly affect studies, these associations could be databases. Meta-analyses, randomised the elderly population [ 1 – 3 ] . Autopsy coincidental. The only persistent cofounder controlled trials, systematic reviews, studies reported a 50% incidence of of all reported associations is increasing age controlled cohort studies and observational renal cysts after the age of 50 years [ 2 ] . [ 5,12,13 ] . It is estimated that 20% of the studies were reviewed. The literature search However, the actual incidence is difﬁ cult population by the age of 40 years, and revealed > 150 studies, of which mainly to determine. Populations having health > 30% by the age of 60 years harbour renal studies published in English language were screening [ 4,5 ] showed lower prevalence of cysts [ 3 ] . reviewed. Excluding the vast majority of simple renal cyst than populations who case reports and irrelevant studies, ≈ 100 were admitted or followed at clinics [ 6 – 8 ] , Simple renal cysts usually remain untreated studies were available for citation. The while the prevalence of simple renal cyst requiring intervention only when they cause creation of tables incorporating the results detected by CT was higher than the symptoms or undergo a complication [ 5,14 ] . of simple renal cyst aspiration and prevalence determined by ultrasonography Herein, we have performed a systematic sclerotherapy for future literature (US) [ 9 ] . review of conservative treatment and comparison was intended. radiological intervention for simple renal It is thought that renal cysts originate by cysts. RESULTS the weakening of the tubular basement membrane of the distal convoluted or MATERIAL AND METHODS CONSERVATIVE TREATMENT OF SIMPLE collecting duct cells. As a result, a diverticula RENAL CYSTS is formed that can subsequently develop in We performed a systematic literature search to a simple renal cyst [ 10,11 ] . Risk factors using the terms ‘ renal cyst ’ , ‘ natural history ’ , The decision to treat or not to treat for the formation of renal cysts are serum ‘ observation ’ , ‘ conservative treatment ’ , asymptomatic simple renal cysts should be

Although more and higher level evidence is TABLE 1 Bosniak renal cyst classifi cation needed, essentially the current evidence is not to pursue asymptomatic benign renal Stage Cyst wall Septa Calcifi cation Enhancement cysts even when these are increasing in size. I Hairline thin No No No Although there no evidence-based II Minimal regular Few, hairline thin Smooth, hairline No guidelines the available data suggests that thickening thin class II Bosniak cysts are benign but may IIF * Minimal regular Multiple, minimal Thick, nodular No need periodic evaluation by US for the fi rst thickening smooth thickening 2 – 3 years, especially in younger patients III Irregular Measurably thick, Thick, nodular, Yes with cyst diameters of > 3 cm. Class IIF cysts thickening irregular irregular should be followed by CT at 3, 6 and 12 IV Gross irregular Irregular gross Thick, nodular, Yes, tissue months and annually thereafter [ 13,15 ] . This thickening thickening irregular and cyst follow-up approach has been shown to be safe and has prevented an unnecessary * F in IIF is for follow-up. Cyst size of > 3 cm in diameter is another criterion for follow-up and by surgical intervention in > 95% of patients extension inclusion in class [ 18 ] . [ 18,25 ] .

In 2 – 4% of the cases, simple renal cysts become symptomatic due to enlargement or the development of a complication such as based on the natural history of this entity. Only a few studies have reported a clinical haemorrhage, infection or rupture. In At diagnosis, 70 – 80% of simple renal cysts course of malignant change from simple addition, they may cause calyceal or renal are solitary unilateral and cortical [ 15 ] . Renal renal cysts. These studies mainly presented pelvic obstruction [ 8,13 – 15 ] . They may then cysts tend to progress in number and size case reports [ 20 – 22 ] . When pathology was present with fl ank pain, abdominal with age, while spontaneous regression is correlated with the Bosniak classifi cation, discomfort, a palpable mass, or haematuria. extremely rare [ 16 ] . Long-term follow-up of the risk of malignancy occurring in a simple However, in a controlled epidemiological patients with asymptomatic cysts showed cystic lesion was 1.7% [ 23 ] . In a prospective study of 1526 consecutive patients the that the diameter of a renal cyst may study of 61 patients with simple renal cysts prevalence of hypertension, fl ank pain, increase by ≈ 1.6 mm or about 5% annually, followed for up to 14 years, only two erythrocytosis, haematuria, and proteinuria and may double the original size over 10 developed renal neoplasms originating from was not increased in patients with simple years [ 5,7,17 ] . Simple cysts tend to increase the renal cyst [ 5 ] . Bosniak category II lesions renal cysts. The association of these rapidly in size during the fi rst 2 or 3 years are minimally or moderately complicated symptoms with simple renal cysts has to be after recognition, but their enlargement cysts for which radiographic surveillance is considered merely coincidental [ 8 ] . Clinical decelerates with longer follow-up periods. usually recommended, as the risk for symptoms are more common with neoplasm The vast majority of renal cysts increase in malignancy is 5 – 10% [ 23,24 ] . In all these than simple cysts, and the onset of size to less than twice their original size [ 5 ] . studies, the total number of patients symptoms should always raise the possibility included was small and it is likely that the of an associated malignancy and the need Several studies indicated that cyst real risk of malignancy in simple renal cysts for additional diagnostic studies [ 13 ] . aggressiveness is predicted by age, cyst is actually much lower than the shape and laterality. Renal cysts in younger aforementioned [ 5,23 ] . These studies The association between simple renal cysts patients progress more rapidly than those in indicated that neither the actual size nor and the incidence of hypertension is older patients, while multi-loculated cysts size changes were specifi c for the controversial. Since the initial report about grew more rapidly than simple cysts. development of a renal neoplasm. The rate the development of hypertension by simple Bilateral cysts may also be more aggressive of increase in the cyst size in patients with renal cyst by Farrell and Young [ 26 ] , several compared with unilateral ones [ 5,7,17 ] . renal cancer was similar to that in other authors reported cure or improvement of Based on the Bosniak renal cyst patients of the same age. Based on these hypertension after decompression of a large classifi cation system, multi-loculated cysts data it is extremely diffi cult to clarify cyst [ 27 – 30 ] . Most studies currently indicate are classifi ed into category 2, which do not whether the regular follow-up of the renal that when patients are stratifi ed with require further evaluation ( Table 1 [ 18 ] ). cysts is of benefi t in the early detection of a clinical parameters associated with Category IIF lesions are well-emarginated malignancy. Patient prognosis in the above hypertension, the presence of cyst is containing multiple hairline thin septa or studies was mainly determined by the related to hypertension but not to renal minimal smooth thickening of their wall or histological type of the malignant lesion at dysfunction. The number and the size of the septa without measurable enhancement. diagnosis [ 5 ] . Radiographic surveillance is an cysts are independent risk factors to the These lesions are considered to be benign, effective method for managing patients prevalence of hypertension [ 4,11,31,32 ] . but require follow-up with CT. Their with minimally or moderately complex renal confi guration should be stable over time cysts. Malignant lesions can be identifi ed RADIOLOGICAL INTERVENTION with changes in the cystic wall shape and removed while still of low grade and indicating a cystic renal neoplasm, stage and surgery can be avoided in most Symptomatic simple renal cysts can be necessitating further evaluation [ 18,19 ] . patients [ 24 ] . treated in various ways ranging from simple

aspiration with or without the use of system can be excluded. Adapting modern volume, the maximal dose being 75 – 200 mL sclerotic agents, to surgical excision via CT techniques and keeping the number of CT in various reports [ 53,55 – 60 ] . Although open, percutaneous, laparoscopic, or robotic slices to a minimum reduces the radiation volumes of ethanol up to 350 mL have been surgery [ 5 ] . Imaging guided percutaneous dose to the patient [ 93,96 ] . uniquely administered for the treatment of renal cyst aspiration with or without a giant renal cyst without any complication sclerosing therapy has been performed to Simple cyst drainage without sclerotherapy [ 46 ] , the vast majority of the studies have treat simple renal cysts since 1970s. The is associated with a recurrence rate of used < 100 mL of ethanol as their upper method has been considered minimally 30 – 80%. The secretory epithelium, lining the limit. invasive, safe and of low cost [ 33 – 98 ] . cystic wall, leads to the high rate of fl uid re-accumulation after simple aspiration Ethanol is most commonly applied in a However, the procedure has not been [ 33,35,42 ] . In fact, the water turnover in prolonged 20-min single-session standardized as yet. US and CT have both simple renal cysts can be as high as [ 39,41,42,44,47,53,55,57 – 59,63,86,96 ] . been used to guide therapy and document 200 mL/24 h [ 31 ] . In most cases after simple However, recurrence rates of > 30% have its result, but no comparative study exists aspiration cyst fl uid re-accumulates so that been reported and multiple sessions may be between the two imaging methods. The 24 months after treatment there is no required to achieve a durable result ultimate outcome of the procedure has not difference in size between cysts that were [ 43 – 45,47,50,52,59,88,95,97 ] . Multiple been clarifi ed. Renal cyst disappearance, aspirated and those that had no treatment sessions are time-consuming (12-h to 2-day reduction of cyst size or fl uid volume and [ 43 ] . interval between sessions) and may be elimination of patients ’ symptoms have all related with increased ethanol leakage and been used separately as endpoints of Attempts have been made to destroy the additional patient discomfort. The latter is treatment success. The improvement in secretary epithelium by injection of various associated with the occurrence of infection, symptoms is not necessarily associated with sclerosing agents into the cysts to reduce the multiple punctures needed for repeated complete resolution of the cyst, while the rate of recurrence. Various slcerosants aspiration or with the placement of a disappearance of the cyst is not always have been used to provoke infl ammation catheter in the renal cyst for several days associated with symptom relief. The duration and adhesion of the cystic wall. These for complete drainage of the transudate by of success and follow-up of the result varies agents include ethanol [ 33 – 64 ] , glucose [ 65 ] , sclerotherapy. in the published data. phenol [ 66 ] , pantopaque [ 35,67,68 ] , bismuth phosphate [ 69,70 ] , ethanolamine oleate The recurrence of renal cysts after In addition, although favourable therapeutic [ 71 – 74 ] , quiacrine hydrochloride [ 71,75 ] , sclerotherapy is attributed to incomplete outcomes have been reported by varying the morrhuate sodium [ 76 ] , tetracycline and ablation of the cyst wall. The recurrence is sclerosing technique and the agent, the mynocycline [ 77 – 80 ] , fi brin glue [ 81 ] , carbon mainly due to the dilution of ethanol by the optimal technique of treating renal cysts dioxide [ 82 ] , polidocanol [ 83 ] , acetic acid fl uid remaining in the renal cysts. In and the best agent for renal cyst [ 84 – 89 ] , povidone iodine [ 90,91 ] , n-butyl addition, the collapsed cyst after aspiration sclerotherapy remain to be determined. cyanoacrylate and iodized oil [ 92,93 ] , of the content might have many folds Several factors in renal cyst sclerotherapy chitosan [ 94 ] , sodium tetradecyl sulphate with pursed areas inaccessible to ethanol. require optimisation. These factors include (STDS) [ 95 ] , hypertonic saline [ 96 ] and This pertains especially to extremely large the choice of the agent, its concentration OK-432 [ 97,98 ] . cysts (> 500 mL liquid evacuated) or when a and volume in relation to cyst volume, the low volume of the agent is injected [ 41,88 ] . duration of sclerotherapy per session, the Several factors must be considered before number of injections required in relation to selecting the most effective agent with the The use of a three-way tube to prevent cyst volume, patient position after least complications. Such factors include the air from getting into the renal cyst, sclerosant administration, whether toxicity, adverse systemic and local effects, repetition of fl uid aspiration to reduce the continuous drainage is needed before and secondary infection, availability and presence of debris adherent to the cyst wall after slcerotherapy, and duration of cost-effectiveness. Several materials used as [ 52 ] , continuous-negative pressure catheter drainage. sclerosants in the past have been abandoned drainage [ 63 ] , continuous drainage of the because of adverse reactions. cyst for 24 h before therapy [ 54 ] , prolonged Both US-fl uoroscopy combination [ 33 – contact of the cyst wall with the sclerosing 63,65 – 92,94,95,97,98 ] and CT [ 64,93,96 ] are Ethanol is the most commonly used agent for 90 min [ 53 ] to 4 h [ 58 ] , no used in percutaneous treatment of renal sclerosing material for cyst ablation [ 33 – 64 ] drainage of the agent after fi nishing the cysts. Real-time US is preferred if the cyst is ( Table 2 [ 39,41 – 44,47,48,50,52,54,57 – procedure [ 57 ] and multiple injections allow clearly visualised and a safe access route 59,63,64 ] ). When injected at 95% or 99% ethanol to reach the entire cyst wall in high can be guaranteed. US is cost-effective and concentrations it rapidly destroys (1 – 3 min) concentrations [ 43 – 45,48,50,52,59,88,95,97 ] . without radiation but it is very dependent the secreting cells on the cystic wall, Finally, monitoring ethanol concentration upon the skill of the operator. CT is without affecting the renal parenchyma, as with measuring fl uid density during CT may preferable in diffi cult anatomies and body it penetrates the fi brous capsule of the cyst increase the success rate of sclerotherapy habitus such as the obese patients. In in 4– 12 h. The time of exposure to the [ 64 ] . addition, by injecting i.v. contrast medium sclerosant varies widely from 10 min to 4 h the presence of a communication between [ 58,60 ] . The volume of alcohol injected after There may be a relation between the degree the simple renal cyst and the collecting aspiration varies from 20% to 50% of cyst of response and cyst size, with larger cysts

172 © 2012 BJU INTERNATIONAL CONSERVATIVE AND RADIOLOGICAL MANAGEMENT OF SIMPLE RENAL CYSTS (1) bleeding (1) Fever (2) fever (7) Nausea (3) Complication (number of patients) Volume Volume reduction,% na 0 6 reduction stable 6 increased Symptoms disappearance, % Cyst size reduction (% of cysts) Cyst disappearance, % 6019 919 100 29 61.5 0 38.5 na 100 100 na na na Na Fever (2) Follow-up, months 28 21.4 57.1 100 97.9 60 71 22 66 na Na 36 76 21 100 na (3) Haemorrhage (1) Pain 24 52 na 0 mL 0 uoroscopy, single uoroscopy, 24 20 na na na injections (for large cysts) cysts) cysts) retained material injections (for large cysts) drainage drainage US, single multiple US, single (small US, multiple (large US/CT, number of US/CT, sessions US, single 6 56.6 36.6 93mL 11.6 0 US, multiple 55 22 na 75 asymptomatic US, single 4 h US, single 4 singleCT, 6 55 25 na na Flank pain (5) Fever (3) US, single multiple US, multiple 30 83.82 11.76 na na (6) Pain US, singleUS, continuous 24 28 na 93mL 18.5 Intoxication (8) Headache 100/na) 100/na) < < 150/na) 100/na) 150/na) 100/na) 100/na) 100/na) < < < < < < cyst puncture instilled with instilled 24 h instilled 24 after cyst puncture 95 ( 99.5 ( 95 ( 95 ( % Ethanol (mL/% of cyst volume) 95 ( 95 ( 99 ( 99.9 ( Cyst size cm/ volume mL 64 30 na/280 40 6.75/na 99 US, multiple 15.4 73 23 91 na (10) Pain/fever 13 95 (na/25) US, multiple 24 100 na na na 19 95 (na/25) US, single 24 68 na na na (2) haematuria Pain/fever 42570– 9.8/100 95 (na/33) US, single prolonged 46 na/330 238 9.1/394 99 (20/na) 252 8.8/357 99 (20/na) No cysts . .

. . al

al . [ 50 ] 32 7.8/na al . [ 52 ] 17 10/na 99.8 (na/15) US, multiple 12 85.7 14 100 na Abdominal discomfort

. ] [ 41 30 na/170 95 US, single 19 83 17 100 na Microscopic haematuria (2)

et . [ 43 ] 72 10.8/na 95 US, multiple 48 97 – 56 na Surgical exploration for al al . [ 48 ] 77 8.62/na

et al

et . [ 44 ] 42 6.12/na 99 US, single 12.9 19 38 71.4 na 0 . [ 42 ] 20 na/25 – 500 Aspiration US/ﬂ

. [ 63 ] 46 na/309 al . [ 39 ] 22 na/190 – 780 96 (na/25) US, single 3 – 6 100 na na na Microscopic haematuria (2) al

et al al al et al Simple renal cyst sclerotherapy with ethanol with ethanol cyst sclerotherapy Simple renal

et . [ 58 ] 14 8.3/223 . [ 64 ] 45 6.53/na et et 2 et et

al al

et et Gomha [ 59 ] [ 57 ] [ 47 ] [ 54 ] Mohsen and Falci-J ú nior na, not available Lin Ö zg ü r Hanna el-Diasty TABLE TABLE Reference Zerem Chung Paananen Touloupidis Fontana Delakas De Dominicis Gasparini Xu

necessitating multiple injections [ 48,59,95 ] . Interestingly, the complete disappearance of the cyst may take as long as 6 – 12 months, and as a consequence, abdominal US showing residual cyst during this period (2) Fever (5) Eczema (1) (3) does not signify failure or recurrence. Initial vomiting (3) Leukocytosis (4) Complication (number of patients) relapse of a cyst after ethanol sclerotherapy Fever (1) may be secondary to transient, reactive or inﬂ ammatory ﬂ uid collections, which eventually disappear within several months

[ 57,62 ] . 93) Volume Volume reduction, % Alcohol injection is associated with complications, including pain, fever, and systematic reactions, e.g. intoxication and shock. The complications are more common in the management of large cysts, which Symptoms disappearance, % require more alcohol for sclerosing. Pain can be avoided by injection of a local anesthetic in the cyst before the injection of the

sclerosing agent and/or with systemic Cyst size reduction, % of cysts analgesia 30 min before the procedure, or sedation [ 42,57 ] .

Alcohol intoxication is an extremely rare

complication. When hepatic cysts have been 0 5 na na Fever (2) 44.8 31.8 na na (21) Pain/fever treated by ethanol sclerotherapy the mean Cyst disappearance, % (SD ) blood alcohol concentration was found to be 0.38 (0.32) g/L in all measured patients and the highest value was 1.02 g/L [ 40 ] . 3 3 36 44 50.7 na 79 (8) Haemorrhage Pain 36 10 27 na 5 (4) Haemorrhage Pain > > Ethanol sclerotherapy of renal cysts may Follow-up, months lead to measurable alcohol levels in the blood in 40% of patients. The values are low enough (0.01 – 0.30 g/L) to treat the patients uoroscopy, uoroscopy, safely on an outpatient basis. Increased uoroscopy, single levels were detected in cases with some single US/ﬂ US/CT, number US/CT, sessions US, single 10 76.7 20 na na (9) Nausea/ Pain US, single 30.5 66 97.4 100 na 0 haemorrhage into the cyst caused by the puncture [ 50 ] . When alcohol intoxication occurred, the maximum blood alcohol concentration was 73 – 120 mg/dL at 3 h 0.1 – 0.6 g after alcohol instillation. All symptoms and + signs disappeared during the ﬁ rst 24 h after 100/20) < bismuth phosphate (na/23) the procedure [ 63 ] . When large cysts are ( Aspiration Sclerosant (mL/% cyst volume) treated and a volume of > 100 mL ethanol is Ethanolamine oleate US, single 3 0 na 10097 (mean – 90 anticipated it is recommended that ethanol dose titration with an alcohol breath analyzer should be done in each and every 6/60 – 150

case. × Cyst size, cm/ volume mL 9 Extravasation of the sclerosing agent is a 59 5.2/na 30 4.7/na Aspiration US, single 20 Aspiration US, single 9.9 5 20 na na na 6257 3.1/na 5.4/na Observation Aspiration US/ﬂ 36 0 7 na 0 rare complication. It rarely causes serious 35 na/283 50% acetic acid (na/8) US, single 27.3 63 96.9 100 na 0 problems even when peripelvic cysts have No cysts been treated [ 48,58 ] , although ﬁ brosis of the PUJ and subsequent obstruction have been . [ 74 ] 4 al reported [ 36 ] . . [ 78 ] 177 5.5/na Minocycline US, single . [ 90 ] . ] [ 91 5 16 6 – 15/na 3 – 10.5/na Povidone-iodine Povidone iodine US, single US, multiple 22 7.2 18.5 60 na 20 25 100 33 – 86 na 0 0 . [ 93 ] 27 5.6/na NBCA and iodized oil CT, single 9.1 na 2.1 87 na 0 et al . [ 87 ] 32 na/245 50% acetic acid . [ 80 ] 56 6.9/na Tetracycline US, single 9.8 39.3 46.4 89.7 na na

al al . [ 83 ] 15 3% polidocanol US, single 1 – 24 93 na na na 0 . [ 98 ] al 61 8.2/na OK-432 US, single 12 74 22.9 100 na Pain (12) Fever (6)

Simple renal cyst sclerotherapy with agents other than ethanol with agents other than ethanol cyst sclerotherapy Simple renal al

. [ 89 ] 60 na/244 50% acetic acid al et

et et

3 al et

et et Bleeding in a voluminous cystic cavity after et et rapid percutaneous drainage can occur. Hietala ] [ 70 Ohkawa Kilinc Ohta Phelan Madeb Yamamoto Choi Baysal Holmberg and TABLE TABLE Reference NBCA, n -butyl-cyanoacrylate; na, not available. Kwon Some investigators registered up to Yoo

57 cmH2 O at percutaneous puncture of renal cysts [ 34,38 ] .

It seems that the success rate with ethanol is better (97%) than that reported with Leukocytosis (3) (2) Pain score 3.8 (2) Pain score 2.1 (1) Pain Leukocytosis (2) pantopaque (23 – 82%) [ 67,68 ] , bismuth Complication (number of patients) phosphate (44 – 81%) [ 69,70 ] , minocycline and tetracycline (44 – 71%) [ 77 – 80 ] , povidone-iodine (18 – 60%) [ 90,91 ] , ethanolamine oleate (65 – 97%) [ 71 – 74 ] ,

Volume Volume reduction, % carbon dioxide (71 – 100%) [ 84 ] , and chitosan (90%) [ 94 ] ( Table 3 [ 70,74,78,80,83,87, 89 – 91,93,98 ] ). However, other sclerosants such as acetic acid (66 – 96.7%) [ 84 – 89 ] , STDS [ 95 ] and OK-432 [ 97,98 ] seem equally or more effective than ethanol. Symptoms disappearance, %

There are several studies directly comparing ethanol with other slcerosing agents [ 86,88,95 – 97 ] ( Table 4 [ 49,86,88,95 – 97 ] ). Acetic acid has a strong ability to penetrate

Cyst size reduction (% of cysts) cells and can dissolve lipids and extract collagen. Acetic acid has been reported to be an effective sclerosing agent for renal cysts owing to its faster and more complete sclerosing effect compared with ethanol. In addition, the amount of sclerosing agent 66 89 na na (3) Pain 32 72.8 na na (3) Pain

Cyst disappearance, % and the frequency of the procedure are decreased when acetic acid is used [ 86,88 ] . Demir et al . [ 95 ] in a randomised study, 9.2 82 9 na na Haematuria (2) Fever 9.5 26 18 na nacompared Haematuria (1) Fever ethanol to STDS, an embolization 12 12 Follow-up, months > > agent. Both agents were simple noninvasive, cost-effective and well tolerated sclerosants ed ed for the treatment of simple renal cysts. STDS caused less pain and it may be preferable. Egilmez et al . [ 96 ] in a randomised trial

ng 17.7 100 na 100 nareported that Transfusion (1) ethanol sclerotherapy under uoroscopy, single uoroscopy, uoroscopy, single uoroscopy, to cyst size) to cyst size) CT guidance was more effective than US, single 18 90.6 9.4 97 97.3 (15) Pain CT, singleCT, singleCT, 6 6 94 72 2.7 2.7 na na (10) Pain 0 US, single 14 75.4 23 100 na (6) Fever (3) Pain US, multiple 13 60 30 80 86 (5) Pain US, single 17 na na 0 na (1) Pain US/ﬂ US/ﬂ 20% hypertonic saline sclerotherapy. Sclerotherapy was more effective in the 25 < 25) 25)

< ethanol group while hypertonic saline may <

100/ 100/ be an option for patients preferring to < 200/24.5) 100/25) 100/ 100/ 75/20) < < < < undergo a less painful treatment procedure.

100/25) OK-432 is a lyophilized incubation mixture < of the low virulent Su strain of type III, 100/25) < ( group A Streptococcus pyogenes of human Sclerosant (mL/% of cyst volume) number sessions US/CT, OK-432 ( 50% acetic acid (na/ 95% ethanol ( 95% ethanol ( 50% acetic acid/ 99% ethanol ( 99% ethanol ( origin with penicillin G potassium that has lost its streptolysin S-producing ability. The mechanism of action of OK-432 is probably damage to the endothelial lining which

Cyst size, cm/ volume mL causes obliteration of the cavity and prevents further accumulation of ﬂ uid in the

7 8/250 Laparoscopy de-rooﬁ lesion. OK-432 does not penetrate the cystic 61 8.2/337 No cysts 36 na/178 20% hypertonic saline 32 na/208 36 na/165 34 8.5/256 3% STDS (na/25) US, multiple (stratiﬁ 32 na/301 wall, does not cause any scarring of the

. renal parenchyma and as a result, drainage . [ 95 ] 34 8.5/252 95% ethanol (na/25) US, multiple (stratiﬁ . [ 49 ] 6 6/90 al

. [ 97 ] ] 97 [ . 50 8.4/359 99% ethanol (na/25) US, multiple 22 68 16 90.3 na (13) Fever (4) Pain al al Simple renal cyst sclerotherapy: comparative studies studies comparative cyst sclerotherapy: Simple renal . [ 88 ] 40 na/168 . [ 86 ] 28 na/209

is not required. Ham et al . [ 97 ]

et al al

4 al et

et retrospectively compared the result of et et [ 9 6 ] ethanol 99% multiple injection sclerotherapy TABLE TABLE Reference na, not available. Cho Okeke Egilmez Ham Seo Demir with OK-432 single injection sclerotherapy.

The latter was simpler, safer and more CONFLICT OF INTEREST S . Should a benign renal cyst be effective for the treatment of simple cysts, aspirated? Br J Urol 1983 ; 55 : 457 – 9 especially large cysts. None declared. 15 Bisceglia M , Galliani CA , Senger C , Stallone C , Sessna A . Renal cystic Ethanol sclerotherapy has been compared diseases: a review . Adv Anat Pathol with other treatment methods for simple REFERENCES 2006 ; 13 : 26 – 56 renal cysts. Okeke et al . [ 53 ] have compared 16 Kessel HC , Tynes WV . Spontaneous single-session ethanol sclerotherapy and 1 Laucks SP Jr , McLachlan MS . Aging regression of renal cysts . Urology 1981 ; laparoscopic de-roofi ng in the management and simple cysts of the kidney . Br J 17 : 356 – 7 of symptomatic simple renal cysts with a Radiol 1981 ; 54 : 12 – 54 17 Dalton D , Neiman H , Grayhack JT . The limited number (six and seven patients in 2 Kissane JM , Smith MG . 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