Ultrasound-Assisted Drainage and Alcoholization of Hepatic and Renal Cysts: 22 Cases
Twenty-two dogs and cats with symptomatic renal or hepatic cysts that had undergone ultrasound-assisted drainage and alcoholization were retrospectively evaluated. Common presenting complaints were anorexia, reluctance to move, and vomiting. Abdominal pain was observed in all cases. Systemic hypertension was identified in four dogs and four cats with renal cysts. Cyst drainage and alcoholization were achieved without complications in 19 animals, and all clinical signs resolved after the procedure. In three cases, transient bleeding was observed during alcoholization, and the procedure was interrupted. Blood pressure normalized in the four dogs with renal cysts, but it remained elevated in the four cats.
Introduction
Renal and hepatic cysts are epithelium-lined cavities filled with a liquid of differing composition, depending on the organ of origin and presence of complicating factors.1,2 The lesions may be single or multiple. Cysts can be classified as simple (i.e., the contents do not contain cells, bacteria, or fungi) or as complicated.1,2 The pathogenesis of the cysts is not well defined.3 The epithelial cells lining the cyst are metabolically active, and the dynamic activity of these cells is responsible for any progressive increase in volume of the cyst.3 In humans, the cysts can cause ischemia in the surrounding renal parenchyma, leading to renal failure and to activation of the renin-angiotensin-aldosterone system, with development of systemic hypertension.4–6 Renal cysts in humans can also cause urinary obstruction from compression of the renal papillary ducts or the renal pelvis.1,7 With regard to hepatic cysts in humans, obstruction of the biliary tree is the most important complication, although rare.8 In people, common complaints with either renal or hepatic cysts are pain, decreased physical activity, and decreased appetite.1,2,9,10 In most cases, cyst drainage and alcoholization improve renal hypertension, urinary and biliary obstruction, and clinical signs.2,6,9,11,12
In dogs and cats, renal cysts are commonly observed in breeds predisposed to polycystic kidney disease, where the cysts may cause renal failure.13,14 In animals, cysts can also be found secondary to chronic nephropathies. In these latter cases, the cysts usually occur as single lesions.15 Less frequently, solitary renal cysts have been recognized as incidental findings in clinically healthy dogs.16 Obstruction of the proximal ureter has been documented in one cat, and obstruction of the renal pelvis has been described in a dog.17,18 With renal cysts, clinical signs are generally related to kidney failure, and abdominal pain is not always recognized in dogs and cats.19,20 Systemic hypertension has been reported with renal cysts in cats, although its clinical relevance is debated.17,19,20 Hepatic cysts in cats and dogs are generally associated with liver tumors, polycystic kidney disease, liver hydatidosis, and congenital hepatopathies.14,21–25 In these conditions, cysts do not always contribute to the clinical signs.21,24
The aim of the present study was to characterize the clinical and laboratory features of dogs and cats with symptomatic renal and hepatic cysts. The ultrasonographic technique of cyst drainage and alcoholization, as well as the complications and short-term outcomes were also evaluated.
Materials and Methods
The clinical records of dogs and cats admitted between October 2002 and October 2004 with a diagnosis of symptomatic renal or hepatic cysts that were submitted to ultrasound-assisted cyst drainage and alcoholization were retrospectively evaluated. Animals were excluded if ultra-sonographic follow-up was not available at 3 to 4 weeks following the procedure. From the clinical records, information was collected on signalment, major complaints and physical findings at presentation, results of laboratory tests, ultrasonographic findings, and systemic blood pressure measurements. Blood pressure was evaluated on admission, 24 to 48 hours following intervention, and 3 to 4 weeks after intervention.
To perform drainage and alcoholization of cysts, all animals were fasted for 12 hours prior to intervention. Tramadola (2.0 mg/kg intramuscularly [IM]) was administered 1 hour before induction of anesthesia, which was done with intravenous (IV) propofolb (dogs, 6.5 mg/kg; cats, 8.0 mg/kg). Anesthesia was maintained by repeated IV boluses of propofol (1.0 mg/kg). The intervention was carried out in a single session using two consecutive alcoholizations of the cystic cavity. The cyst was drained using a spinal needle (22 or 23 gauge) introduced via an ultrasound-assisted, percutaneous approach. Once the needle was positioned in the cystic cavity, the stylet was removed and connected to a three-way valve. Drainage of the cystic fluid was slowly achieved by aspiration with a syringe. In each case, the syringe volume was never more than double the estimated cyst volume. To avoid excessive negative pressure when aspirating the cyst and to have better manual control during the procedure, larger syringes were not used. An aliquot of 0.5 mL of the cystic fluid was collected in sterile, buffered transport medium and kept at 4° to 8°C for aerobic bacterial culture. The remaining amount of liquid was used for cytology. Slides were stained with May-Grünwald Giemsac and were examined by the same person.
When drainage of the cyst was completed, a volume of 95% ethanol that was equivalent to half of the amount drained was injected through the same needle. The alcohol was left in the cyst cavity for 3 minutes and then slowly removed. The alcoholization was repeated with 2% lido-cained added to the alcohol (lidocaine to alcohol solution volume was 1:10). The mixture was left in place for 3 minutes and was again drained. Tramadol (2 mg/kg IM or per os at 12 hours) was stopped 24 hours after the procedure if pain was not identified with abdominal palpation.
Blood pressure was measured by Doppler sphygmomanometrye in a quiet room after a 10- to 20-minute period of acclimatization. Five measurements were obtained with the animal in lateral recumbency, and they were repeated after 5 to 10 minutes. The mean blood pressure was calculated, excluding the highest and lowest values. For dogs and cats, cuffs that were 40% and 30% of the front limb circumference were used, respectively. Systemic hypertension was defined as systolic values >150 mm Hg in dogs and >170 mm Hg in cats.26
Results
Clinical Findings
Renal cysts were diagnosed in 10 animals (five dogs, five cats), and hepatic cysts were diagnosed in 12 animals (three dogs, nine cats) [Figures 1, 2]. Eight dogs and two cats were intact males, seven cats were castrated males, four cats were spayed females, and one cat was an intact female. Median age for dogs was 11 years (range 8 to 13 years), and for cats the median age was 7 years (range 3 to 12 years). One dog was a German shepherd dog, another was a West Highland white terrier, and the remaining were mixed-breed dogs. Ten cats were Persians, two were domestic shorthairs, and two were exotic shorthairs.
In the five cats with renal cysts, one large cyst was present in each case, and some smaller cysts were present in some cats. In these cases, drainage and alcoholization were performed only on the most prominent cyst. In four of the cats with hepatic cysts, some small cysts were also found in the kidneys. In the remaining animals, only single renal and hepatic cysts were present. The median sizes of the renal cysts were 35 mm (range 28 to 65 mm) in dogs and 25 mm (range 19 to 32 mm) in cats. For the hepatic cysts, median sizes were 38 mm (range 35 to 43 mm) in dogs and 20 mm (range 15 to 26 mm) in cats. Polycystic renal disease was found in the five cats with renal cysts and in four cats with hepatic cysts and small cysts in the kidneys. In five dogs with a renal cyst and in three dogs and five cats with hepatic cysts, the primary renal and hepatic disorder was not established. In these cases, ultrasonography of the kidney and liver parenchyma was normal, but biopsy was not pursued.
Complaints at presentation included anorexia in three dogs and two cats with renal cysts, and in all animals with hepatic cysts. Reduced physical activity was noted in all animals with renal cysts and in two dogs and eight cats with hepatic cysts. Vomiting was reported in three cats with renal cysts and in five cats with hepatic cysts. The major finding on physical examination was pain upon abdominal palpation, which was identified in all animals. An enlarged and irregular kidney was palpated in each of the five cats with renal cysts. An abdominal mass was palpated in a dog with a renal cyst.
Laboratory Results
Among the animals with renal cysts, one cat was mildly anemic (hematocrit 27%; reference range 30% to 45%). The same cat and two others had mild to moderate azotemia (average serum creatinine was 3.5 mg/dL; range 2.4 to 4.1 mg/dL; reference range <1.6 mg/dL). Two of the azotemic cats also had low urine specific gravity (1.019 to 1.022; reference range 0.035 to 1.060). On urinalysis, microscopic hematuria was found in a dog and a cat.
Among the animals with hepatic cysts, anemia was identified in one dog (hematocrit 36%; reference range 42% to 55%) and a cat (hematocrit 21%). In each case, the anemia was nonregenerative. The anemic cat also had mildly elevated alanine aminotransferase (89 U/L; reference range <50 U/L) and elevated bilirubin (0.6 mg/dL; reference range 0.1 to 0.2 mg/dL). Liver enzymes were normal in all other animals. Increased serum creatinine was found in the dog (2.1 mg/dL; reference range <1.5 mg/dL) and cat with anemia, and in two other cats. Average serum creatinine in the three azotemic cats was 3.1 mg/dL (range 2.6 to 3.2 mg/dL). Polycystic renal disease was diagnosed in all three cats. Each of the azotemic animals had reduced urine specific gravity and proteinuria, with a quiet urine sediment. The protein-to-creatinine urinary ratio was 1.8 in the dog (normal value <0.7). In cats, the protein-to-creatinine urinary ratio varied from 0.7 to 3.3 (normal value <0.5). Cytology of the cystic fluid was compatible with a simple cyst in all (n=22) cases, and bacterial culture was negative in all (n=22) cases.
Other Findings
The renal cyst caused dilatation of the renal pelvis in one dog.11 Renal cysts were associated with systemic hypertension in all affected dogs and cats. Systolic blood pressure in dogs ranged from 160 to 190 mm Hg (median 175 mm Hg), and in cats it ranged from 180 to 195 mm Hg (median 190 mm Hg). With regard to animals with hepatic cysts, a 3-year-old exotic shorthair cat also had obstruction of the bile duct. On ultrasonography, the cyst was compressing the duct, which appeared dilated. This cat was the one with documented anemia, increased serum alanine aminotransferase, and increased bilirubin levels. Blood pressure was not determined in any of the animals with hepatic cysts.
Complications and Follow-up
Abdominal bleeding occurred with two renal cysts (in one dog and one cat) and one hepatic cyst (in one dog). In all three animals, bleeding started from the cyst when ethanol was introduced, and the procedure was interrupted in each case. Bleeding was mild, and additional treatment for hemorrhage was not required.
Following drainage and alcoholization, the 19 animals that had no complications showed resolution of their abdominal pain within 24 hours. At 24 hours, abdominal discomfort was still present in the three cases that experienced bleeding during intervention, and oral tramadol was administered. Anorexia, vomiting, and physical activity improved within 3 to 4 weeks following the procedure in the 19 animals without complications. Within 24 to 48 hours, serum creatinine and alanine aminotransferase were normal in these 19 animals. At 3 weeks, serum creatinine was further increased from 3.1 to 3.9 mg/dL in one cat with a hepatic cyst and azotemia. In all other animals with initial laboratory abnormalities, reevaluation at 3 to 4 weeks showed normal renal and hepatic biochemical test results. Blood pressure was normal at 3 to 4 weeks in the four dogs with renal cysts but did not improve in the four cats. In the three animals with bleeding, ultrasonographic evaluation performed 24 to 48 hours after alcoholization showed the formation of a blood clot and/or the presence of echogenic contents in the cyst. On repeat ultrasonography at 3 to 4 weeks, none of the 19 animals that completed the procedure without complications had a recurrence of the cyst. At this time the site of the cystic lesion was replaced by a hyperechoic lesion with indistinct margins, and it was smaller than the original cyst in all cases. In the dog with a renal cyst causing urinary obstruction, the pelvis was no longer dilated. In the cat with bile duct compression, the bile duct remained dilated, even though the hepatic cyst was not identified. In this cat, serum alanine aminotransferase and bilirubin levels did not improve.
Discussion
In humans, one of the most common complaints associated with renal and hepatic cysts is pain, as the lesions distend the innerved organ capsule and stimulate nociceptive fibers.1,2,9,10 In this report, all animals were presented for changes in their behavior that also suggested nociceptive stimulation.27,28 Based on laboratory data, it was unlikely these signs arose from other clinical renal and hepatic disorders. Pain was elicited upon abdominal palpation in all affected animals. Compared to previous reports, the cysts in the animals of the present study were quite large and presumably big enough to distend the organ capsule and elicit pain. In addition, 3 to 4 weeks following the procedure, evidence of pain had subsided, and activity and attitude had improved. Because of its retrospective nature, some bias may have occurred in the assessment of these animals, especially in the follow-up period.
In humans, it is widely accepted that the activation of the renin-angiotensin-aldosterone system is the principal factor causing hypertension with renal cysts.2,4,29 The role of endocrine activation is further demonstrated by the good therapeutic response to angiotensin-converting enzyme inhibitors and the resolution of hypertension after drainage of the cysts.5,6 In the present study, systolic arterial hypertension was found in all animals with renal cysts; however, the response of hypertension to cyst drainage and alcoholization was different in dogs and cats. Even though most cats with polycystic kidney disease are not hypertensive, it is possible that the cats in the present study had more advanced renal compromise and secondary hypertension from activation of the renin-angiotensin-aldosterone system.19,20,30 This possibility may also explain the reason for the different responses observed in dogs, because dogs with renal cysts and hypertension were never azotemic. Another possibility to justify the different response may be related to the number of cysts present. All dogs had a single cyst, while the cats had several cysts. It is possible that relief of renal compression provided by treating one single cyst in the cats was inadequate.
In humans, complications of aspiration of renal and hepatic cysts are uncommon, but abdominal bleeding is the most frequent, especially with cystic lesions of the kidney.31,32 In the present study, the bleeding observed in three animals may have been caused by inadvertent puncture of a vessel or by excessive changes in the internal pressure of the cyst cavity, generated by excessive negative pressure during drainage or overextension of the cyst during alcohol injection. Even though bleeding was observed in some cases, interruption of the procedure was sufficient to prevent further hemorrhage.
Other potential risks related to insertion of a needle in a cystic lesion are seeding of neoplasms and secondary infections.33,34 Tumor metastasis has been described in dogs following fine-needle aspirates of transitional cell carcinomas.33 If this risk also applies to hepatic and renal tumors, it may potentially be offset by the introduction of ethanol to decrease the viability of the tumor cells. Dissemination of bacteria should be of limited concern with proper technique. In fact, drainage and alcoholization have been successfully reported in dogs and cats with hepatic abscesses.34
Another concern is the possibility that renal cyst alcoholization might impair kidney function, but results of the study reported here showed that serum creatinine remained stable over the first 3 to 4 weeks, both in animals that had normal or elevated creatinine levels before the procedure. Even though renal function impairment was not identified in this study, more sensitive diagnostic tools were not utilized. In nonazotemic animals with unilateral renal impairment, further damage could go undetected by routine clinical tests of renal function (i.e., serum creatinine). Alcoholization also appeared to be safe for treating hepatic cysts, in that none of the animals had an increase in liver enzymes following the procedure. One cat’s azotemia worsened, and in this case it was possible that anesthesia and inadequate IV fluid administration during the procedure led to further renal compromise.
Even though the results of this retrospective study showed that drainage and alcoholization of cysts in dogs and cats ameliorated the associated clinical signs, it was not established whether the procedure would also suffice for long-term control. None of the animals were reevaluated with ultrasonography to verify the possibility of cyst recurrence beyond 3 to 4 weeks. Eleven owners were contacted between 4 and 15 months following the procedure, and in all cases the clinical signs had not recurred.
Conclusion
Ten renal cysts and 12 hepatic cysts were diagnosed in dogs and cats. Ultrasound-assisted drainage and alcoholization of the cysts controlled the clinical signs and secondary disorders in most animals. Normalization of blood pressure was not achieved in cats with renal cysts. Based on the minimal invasiveness of the procedure and low rate of complications in this study, the procedure is a valid option for both dogs and cats with renal and hepatic cysts.
Contramal; Prodotti Formenti, Milan, Italy
Rapinovet; Schering-Plough, Milan, Italy
May-Grünwald Giemsa; Mallinkrodt-Baker, Milan, Italy
Lidocaine 2%; Farmaceutici Gellini, Aprilia, Italy
Dop 2001; SAMED, Merlino (LO), Italy
Citation: Journal of the American Animal Hospital Association 43, 2; 10.5326/0430112
Citation: Journal of the American Animal Hospital Association 43, 2; 10.5326/0430112
Simple renal cyst localized in the caudal pole of the left kidney in a 13-year-old, male German shepherd dog. The thin hyperechoic wall, anechoic content (black), and distal acoustic enhancement (white area) are ultra-sonographic features of a simple cyst.
Simple hepatic cyst in an 8-year-old, spayed female, mixed-breed dog. A thin wall, anechoic content, and distal acoustic enhancement are identifiable in this approximately 4.5-cm diameter (between calipers) cyst.
