Introduction Progressive cyst expansion, an infected cyst or significant discomfort or pain in patients with PCKD require prompt and adequate treatment.
Nowadays in these cases, various treatment methods are allowed, such as simple catheter drainage, sclerotherapy with catheter insertion or surgical excision of the cyst.
In sclerotherapy with catheter insertion, leakage of the sclerosing agent leads to serious complications such as pain, adhesion and damage of kidney architecture.
Severe dilation of the renal pelvocalyceal system caused by ureteropelvic junctional obstruction (UPJO) could mimic an enlarged cyst in some cases, and sclerotherapy can lead to severe damage in the urinary tract.
In literature, it is rare to find reports dealing with hydronephrosis mimicking an enlarged cyst in PCKD.
Therefore we show a case of an initially diagnosed enlarged cyst and a sclerotherapy which was planned, but finally, a severe hydronephrosis, caused by the UPJO of upper pole moiety in PCKD with urinary duplication, mimicking an enlarged cyst, was diagnosed.
And the treatment plan was changed to a balloon dilatation or pyeloplasty of UPJO of upper pole moiety.
Polycystic Kidney Disease (PCKD) Autosomal dominant polycystic kidney disease (PCKD) is the most common hereditary kidney disease with a prevalence of 1/500 to 1/1000.
It is the fifth most common cause of end-stage renal disease (ESRD) and constitutes 10% of all chronic dialysis patients (1).
Patients with PCKD frequently suffer from severe, recurrent, and often persistent flank pain that is most often attributed to compression of the surrounding structures by the progressive enlargement of cysts, but it can also be caused by cyst rupture, hemorrhage, or infection (2-5).
In PCKD patients, the use of CT contrast material is limited for preventing deterioration of the renal function, so identification of an infected renal cyst is often difficult on either ultrasonography or CT.
PET-CT (Fig.1) or diffusion-weighted MRI allow exact localization of the infected cyst in PCKD (6).
Radiological Management in PCKD For relieving pain and/or for resolving cyst complications (hemorrhage or infection), prompt and adequate treatment for the dominant or complicated cysts is required.
In these cases, various treatment methods are allowed, such as simple needle aspiration, catheter drainage, sclerotherapy with catheter insertion or surgical unroofing of the cyst. 1.
Simple Needle Aspiration or Catheter Drainage Simple needle aspiration or catheter drainage are easy and safe methods for prompt decompression of the cyst and rapid resolving of cyst complications (hemorrhage or infection).
Simple needle aspiration or catheter drainage are often inefficient because cysts will reaccumulate fluid when the cyst volume is large (1,5) (Fig. 2).
In some cases, with a relatively small-sized complicated cyst, these procedures can make a cyst shrink enough for relieving pain or resolving cyst complications (Fig. 1, Fig. 3). 2.
Cyst Sclerotherapy with Catheter Drainage Surgical or laparoscopic deroofing is invasive and, in the case of recurrence, repeat surgical interventions have limitations (1).
Cyst sclerotherapy with catheter drainage is well-known as a minimally invasive, safe, and effective alternative to conventional surgical/laparoscopic deroofing for decompression of the dominant cysts in PCKD with maintenance of renal function, and repeat procedures are possible in the case of recurrence (1-5).
Various sclerosing agents, such as absolute alcohol, butyl cyanoacrylate-iodized oil, povidone-iodine, sodium tetradecyl sulfate foam, and minocycline hydrochloride, have been used in the management of renal cysts, with varying success rates (1-5). 3.
Ethanol Cyst Sclerotherapy with Catheter Drainage (Fig. 4) Other sclerosing agents are effective only in smaller cysts, may not be safe for repeated use, and are prone to a greater incidence of septic complications (2).
Absolute ethanol as a sclerosing agent has a wide safety margin, a strong aseptic effect, and the capacity to safely sclerose the epithelial lining of the cyst wall without damaging the renal parenchyma.
And alcohol sclerotherapy can be safely repeated in a large cyst with no serious long-term side effects or sequels (1,2).
To establish a successful therapeutic result and possible repeat instillation of ethanol in a large cyst, catheter drainage is preferred in ethanol sclerosing therapy (2).
On the following day, after completely draining the cystic fluid and ascertaining its volume, an amount of ethanol equal to one-quarter to one-half of the volume of the drained fluid or the images-based estimated cyst volume is instilled into the cyst through the catheter (2).
The patient is instructed to lie in the supine, prone, and left and right lateral positions to facilitate adequate exposure of the cyst wall to the sclerosing agent.
The ethanol is then aspirated, and the catheter is left in place for drainage of remaining fluid and for a possible additional treatment session on the following day.
The Pig-tail catheter is removed after completely draining all fluid (2).
In cases in which greater volumes of absolute ethanol (more than 100 mL) are needed to ablate large cysts, an alcohol breath analyzer is necessary to detect significant toxicity for closer monitoring (1).
And full hydration with normal saline through the IV line during the procedure seems to alleviate an alcoholic intoxication. 4.
A Critical Checking Point before Sclerosing Therapy in Patients with PCKD : Differentiation between a dominant cyst and a hydronephrosis mimicking a large cyst In ethanol sclerotherapy with catheter drainage, leakage of the sclerosing agent leads to serious complications such as severe pain, adhesion and damage of kidney architecture (1,2).
Severe dilation of the renal pelvocalyceal system caused by ureteropelvic junctional obstruction (UPJO) could mimic an enlarged cyst in PDKD patients.
In these cases, sclerotherapy can cause severe damage in the collecting system, and can also lead to a serious situation requiring total nephrectomy.
This must be avoided in PCKD patients because maintenance of renal function with preservation of renal tissue is very important to delay the onset of end-stage renal disease in PCKD.
In literature, a few cases have been reported about hydronephrosis due to UPJ obstruction in patients with PCKD (7-10).
However, it is rare to find reports dealing with hydronephrosis mimicking an enlarged cyst in PCKD.
Case We present a case of a diagnosed enlarged cyst for which ethanol sclerotherapy was initially planned, but finally, a severe hydronephrosis, caused by the UPJO of upper pole moiety in PCKD with urinary duplication, mimicking an enlarged cyst, was diagnosed (Fig. 5).
A 42-year-old male patient with PCKD complained about an intermittent flank pain and showed an asymmetric gradual enlargement of one of the cysts in the left kidney on follow-up imaging studies during a 3-year period.
We planned to initially insert an ultrasound-guided percutaneous pigtail catheter into the cyst and ethanol ablation would be performed on a following day after draining of all cyst fluid.
Initial tubography was not performed because the lesion was too large to fully opacify the cyst with contrast material instillation.
The amount of drained fluid during one day was significantly larger (over 1300 mL) than the estimated cyst volume (14.3x7x8.5 cm, 445 mL), and it was suggested that the dominant cyst-like lesion in the left kidney might be a collecting system rather than a true cyst.
With catheterography, DISIDA scan and MR urogram, the dominant cyst-like lesion in the left kidney was finally diagnosed as a severely dilated upper pole moiety pelvocalyces due to UPJO in PCKD with urinary duplication.
DTPA-radioisotope scan was helpful for confirmation of the dilated pelvocalyces in PCKD.
MR urogram clearly showed the UPJ obstruction site which was not definite on unenhanced CT.
In this case, the treatment plan was changed from ethanol ablation to balloon dilatation or pyeloplasty of UPJO of upper pole moiety.
The guide wire was not passed through the UPJO site during the retrograde approach of balloon dilatation, and finally, surgical pyeloplasy with double J-catheter insertion was performed.
Severe adhesion between upper pole moiety UPJ and a vascular structure with thick band formation could be found in the operative field.
Summary It may be possible that severe dilation of pelvocalyces in PCKD mimicks an enlarged cyst on imaging studies, especially in PCKD patients with urinary duplication.
In such cases, ethanol ablation can be dangerous, causing serious damage to the collecting system and may lead to a surgical removal of the affected kidney.
Therefore, differentiation between a true dominant cyst and a severely dilated collecting system is critically important.
Tubography may not be helpful in differentiation between a true dominant cyst and a dilated collecting system when the lesion is too large.
When the volume of drained fluid during one day after catheter insertion is larger than the estimated volume of the lesion with imaging studies (ultrasonogram or CT scan), it could suggest that the lesion might be a dilated collecting system.
DTPA-radioisotope scan is helpful for confirming the dilated collecting system.
MR urogram is effective in differentiation between a dominant cyst and a severely dilated collecting system with clear visualization of UPJO site.
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