Subcutaneous ureteral bypass for treatment of bilateral ureteral obstruction in a cat with retroperitoneal paraganglioma

Corie Borchert Department of Interventional Endoscopy and Radiology, Animal Medical Center, New York, NY 10065.

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Allyson Berent Department of Interventional Endoscopy and Radiology, Animal Medical Center, New York, NY 10065.

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Chick Weisse Department of Interventional Endoscopy and Radiology, Animal Medical Center, New York, NY 10065.

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Abstract

CASE DESCRIPTION A 7-year-old female domestic shorthair cat was referred for evaluation of azotemia and unilateral hydronephrosis.

CLINICAL FINDINGS Abdominal ultrasonography revealed right-sided hydronephrosis and dilation of the proximal aspect of the ureter; the left kidney was small with irregular margins. A highly vascular, irregular retroperitoneal mass, not clearly associated with the ureteral obstruction, was also visualized. Surgical exploration confirmed a retroperitoneal mass involving the caudal mesenteric artery and both ureters, with hydroureter on the right side.

TREATMENT AND OUTCOME A subcutaneous ureteral bypass (SUB) device was surgically implanted to treat right ureteral obstruction, and the mass was biopsied. Shortly after surgery, progressive azotemia and hyperkalemia were detected; ultrasonographic examination revealed left-sided hydronephrosis and hydroureter, which was suspected secondary to inflammation of the mass causing a left-sided ureteral obstruction. A second surgery was performed to place an SUB device for the left kidney and remove the retroperitoneal mass; both ureters were ligated at the mid- and distal aspects and then transected and removed with the mass. A neuroendocrine paraganglioma was identified by histopathologic evaluation of the mass. Hydronephrosis improved (right kidney) or resolved (left kidney) after surgery, and azotemia improved. Chemotherapeutic intervention was declined. Markers of renal function were static during the 14-month follow-up period. At the last follow-up evaluation, the patient was reportedly doing well, and both SUB devices were patent.

CLINICAL RELEVANCE This was the first report of retroperitoneal paraganglioma in a domestic cat causing bilateral ureteral obstruction. Bilateral SUB device placement enabled en bloc mass resection and provided long-term relief of ureteral obstruction.

Abstract

CASE DESCRIPTION A 7-year-old female domestic shorthair cat was referred for evaluation of azotemia and unilateral hydronephrosis.

CLINICAL FINDINGS Abdominal ultrasonography revealed right-sided hydronephrosis and dilation of the proximal aspect of the ureter; the left kidney was small with irregular margins. A highly vascular, irregular retroperitoneal mass, not clearly associated with the ureteral obstruction, was also visualized. Surgical exploration confirmed a retroperitoneal mass involving the caudal mesenteric artery and both ureters, with hydroureter on the right side.

TREATMENT AND OUTCOME A subcutaneous ureteral bypass (SUB) device was surgically implanted to treat right ureteral obstruction, and the mass was biopsied. Shortly after surgery, progressive azotemia and hyperkalemia were detected; ultrasonographic examination revealed left-sided hydronephrosis and hydroureter, which was suspected secondary to inflammation of the mass causing a left-sided ureteral obstruction. A second surgery was performed to place an SUB device for the left kidney and remove the retroperitoneal mass; both ureters were ligated at the mid- and distal aspects and then transected and removed with the mass. A neuroendocrine paraganglioma was identified by histopathologic evaluation of the mass. Hydronephrosis improved (right kidney) or resolved (left kidney) after surgery, and azotemia improved. Chemotherapeutic intervention was declined. Markers of renal function were static during the 14-month follow-up period. At the last follow-up evaluation, the patient was reportedly doing well, and both SUB devices were patent.

CLINICAL RELEVANCE This was the first report of retroperitoneal paraganglioma in a domestic cat causing bilateral ureteral obstruction. Bilateral SUB device placement enabled en bloc mass resection and provided long-term relief of ureteral obstruction.

A 7-year-old spayed female domestic shorthair cat was evaluated by the primary care veterinarian because of an approximately 14-day history of weight loss and hyporexia. The cat had been adopted at 2 years of age and had a history of suspected osteoarthritis. Hematologic and serum biochemical analyses performed by the referring veterinarian revealed CBC results within the respective reference ranges, azotemia (BUN concentration, 38 mg/dL [reference range, 14 to 36 mg/dL]; creatinine concentration, 3.5 mg/dL [reference range, 0.6 to 2.4 mg/dL]), and unremarkable total thyroxine concentration (2.0 μg/dL; reference range, 0.8 to 4.0 μg/dL). Additional serum biochemical screening revealed no evidence of intestinal malabsorption or pancreatitis (cobalamin concentration, 939 ng/L [reference range, 290 to 1,500 ng/L]; folate concentration, 13.4 μg/L [reference range, 9.7 to 21.6 μg/L]; and feline pancreatic lipase concentration by immunoassay, 3.1 μg/L [reference range, 0.1 to 3.5 μg/L]). Urinalysis results indicated mildly low urine specific gravity (1.031; lower reference limit, > 1.035) with mild proteinuria (1+ result on dipstick testing) and inactive sediment. Microbial culture of a urine sample did not yield bacterial growth. Examination of orthogonal abdominal radiographs revealed an irregularly shaped left kidney and hepatomegaly. A presumptive diagnosis of chronic kidney disease was made, and the owner was instructed to feed a feline diet formulated to support renal function. Over the following 2 weeks, the cat appeared increasingly lethargic, had polydipsia, and had vomited once. The owner switched the diet to a commercial wet food because the cat was not eating the recommended food. Results of a repeated CBC performed by the referring veterinarian revealed no abnormalities, whereas serum biochemical analysis identified persistently high BUN (55 mg/dL) and creatinine (3.0 mg/dL) concentrations, although the creatinine concentration was slightly lower than the previous value. Urine specific gravity and proteinuria were unchanged from the previous results. Repeated microbial culture of a urine sample did not yield any growth. Proteinuria was quantified by calculation of the urine protein-to-creatinine ratio, which had normal findings (0.1; upper reference limit, < 0.2). Noninvasive systemic arterial blood pressure evaluation performed at the referring veterinarian's facility revealed mild to moderate hypertension (systolic pressure, 173 mm Hg [upper reference limit, < 160 mm Hg]). Abdominal ultrasonography performed by the referring veterinarian showed a small, irregularly shaped left kidney; severe hydronephrosis of the right kidney (renal pelvis in transverse plane, 2.1 cm; upper reference limit, < 0.2 cm)1; and dense fecal material in the descending colon. The findings were otherwise unremarkable. The cat was referred to the Animal Medical Center, New York, for further evaluation.

On physical examination at the authors' institution, the cat was quiet, alert, responsive, and mildly hyperthermic (rectal temperature, 39.3°C [102.7°F]; reference range, 37.5° to 39.2°C [99.5° to 102.5°F]). A grade 2/6 left parasternal heart murmur was detected on thoracic auscultation. Abdominal palpation revealed a subjectively small left kidney and a normal-sized right kidney; palpation did not elicit splinting in the abdomen. The cat had a moderately distended urinary bladder and mild epaxial muscle wasting. Results of ultrasonographic examination of the abdomen revealed severe dilation of the right renal pelvis (1.93 cm measured in the transverse plane; upper reference limit, < 0.2 cm1; Figure 1) with anechoic contents, mild dilation of the proximal aspect of the right ureter (0.2 cm), and the presence of nonshadowing debris in the proximal portion of the right ureter. The left kidney was small (length, 2.7 cm; reference range, 3.0 to 4.5 cm1) with severely irregular margins characterized by cortical retraction in numerous regions without apparent renal pelvis dilation (< 0.2 cm). The urinary bladder was normal in appearance. Cranial and dorsal to the urinary bladder, a 2.2-cm diameter, heterogeneous, vascular mass was visualized. A large-diameter arterial vessel extended ventrally from the region of the aorta and coursed through the middle of the retroperitoneal mass. This mass was not seen to be associated with either the right or left ureter. Severe hydronephrosis of the right kidney with associated mild proximal hydroureter and intraluminal debris, moderate azotemia, and a retroperitoneal mass were diagnosed. Because of its location, sampling of the retroperitoneal mass by fine-needle aspiration was not performed. Ultrasonographic evaluation of the remainder of the abdomen revealed no abnormal findings. Three-view thoracic radiographs (left lateral, right lateral, and ventrodorsal) were performed; there were no findings consistent with metastatic disease, and the heart was a normal size and shape. Renal decompression was recommended as an attempt to preserve function of the right kidney. After discussion of various options for decompression, placement of an SUB devicea was elected.

Figure 1—
Figure 1—

Preoperative and intraoperative images of a 7-year-old female domestic shorthair cat that was referred for evaluation of azotemia and unilateral hydronephrosis. A—Longitudinal-plane ultrasonographic image obtained at the time of initial examination by the interventional endoscopy service. Severe right-sided hydronephrosis and mild hydroureter are present (calipers show the ureter is 2.6 mm in diameter). Content of the renal pelvis is anechoic. B—Transverse-plane color flow Doppler ultrasonographic image of a heterogeneous retroperitoneal mass at the approximate level of L4 shows a high degree of vascularity, with a large-diameter arterial vessel passing through the middle of the mass. C—Intraoperative photograph of the retroperitoneal mass. The dilated proximal part of the ureter (black arrow) enters the mass (white arrow), and the distal aspect of the ureter, which is not dilated (yellow arrow), courses caudally to the urinary bladder.

Citation: Journal of the American Veterinary Medical Association 253, 9; 10.2460/javma.253.9.1169

Prior to surgery, the cat underwent diuresis with IV fluid therapy for 18 hours (3 mL/kg/h [1.36 mL/lb/h]). The cat was premedicated with midazolam (0.25 mg/kg [0.11 mg/lb], IV) and fentanyl (5 μg/kg [2.3 μg/lb], IV), and general anesthesia was induced with propofol (3 mg/kg, IV). The patient was intubated, and anesthesia was maintained with isoflurane in oxygen. Heart rate, respiratory rate, noninvasive oscillometric blood pressure measurements, oxygen saturation (as measured by pulse oximetry), and end-tidal carbon dioxide concentration were monitored for the duration of the anesthetic period. After induction of general anesthesia, the cat was positioned in dorsal recumbency, and the ventral aspect of the abdomen was clipped of hair and aseptically prepared for surgery. A CRI of dopamine (7.5 μg/kg/min [3.41 μg/lb/min], IV) was administered for the duration of the procedure for management of mild hypotension. Intraoperative analgesia was provided with a CRI of fentanyl (0.5 μg/kg/h (0.23 μg/lb/h], IV). Results of venous blood gas measurements during the procedure indicated metabolic acidosis, and a CRI of sodium bicarbonate solution (IV; dose not recorded) was initiated. An injection of desmopressin acetate (1 U/kg [0.45 U/lb], SC, once) was also administered to decrease the risk of procedural bleeding associated with the potential for uremic thrombocytopathia.2 Crystalloid fluids with 2.5% dextrose (10 mL/kg/h [4.54 mL/lb/h]) were administered for maintenance fluid support throughout the procedure.

A ventral midline abdominal incision was made, and the upper urinary tract was evaluated. The right ureter was severely dilated. The SUB device, comprising a locking loop renal catheter and a fenestrated, cuffed urinary bladder catheter, joined by a shunting port to be located outside of the abdominal wall for subcutaneous access, was placed in a standard manner with fluoroscopic guidance as described elsewhere.3 A large, highly vascularized, multilobulated retroperitoneal mass approximately 2 cm in diameter enveloped the distal third of both ureters for a distance of approximately 1 to 2 cm. The left ureter coursed along the lateral aspect of the mass, and the right ureter passed within the mass (Figure 1). The urinary bladder was not involved. The right ureter was dilated proximal to the mass, but the left ureter was not dilated.

Stay sutures were placed in the retroperitoneal mass to isolate the medial aspect, and immediately the ECG recorded a tachyarrhythmia in response to surgical manipulation. A wedge biopsy of the mass was obtained and submitted for histopathologic examination. Minimal bleeding occurred, and an electrothermal bipolar tissue sealing system was used to ensure hemostasis. Careful attention was paid to avoid any manipulation of the left ureter during biopsy of the mass. The biopsy site was compressed by placement of 4-0 monofilament poliglecaprone 25b suture in a mattress pattern. The abdomen was routinely closed with a 3-layer technique.

A triple-lumen catheter was placed in the right jugular vein, and an ET was placed in the left cervical region. The patient recovered from anesthesia and was monitored in the intensive care unit. Treatments included administration of balanced electrolyte solution (0.45% NaCl with 2.5% dextrose; 2.5 mL/kg/h [1.1 mL/lb/h], IV), pantoprazole (1 mg/kg, IV, q 24 h), maropitant (1 mg/kg, IV, q 24 h), marbofloxacin (5 mg/kg, IV, q 24 h), and buprenorphine (0.01 mg/kg [0.005 mg/lb], IV, q 8 h). A replacement fluid (lactated Ringer solution) was used additionally to maintain body weight on an as-needed basis throughout the following 24 hours. The delivery rate ranged from 1 to 2 mL/kg/h (0.45 to 0.9 mL/lb/h). A slurry of wet cat food designed for renal support3,c was administered via the ET at a third of the resting energy requirement divided over 4 daily feedings. Prazosin hydrochloride (0.25 mg/kg [0.11 mg/lb], q 12 h) and an oral electrolyte solutiond (2.5 mL/kg/h) were also delivered via the ET. The cat was monitored for signs of fluid overload, hemorrhage, and discomfort by observing respiratory rate and effort, measuring heart rate and body weight, and performing noninvasive blood pressure measurements every 4 to 6 hours.

Twelve hours after surgery, progressive azotemia was noted (BUN and serum creatinine concentrations, 75 and 5.0 mg/dL, respectively). The recently placed right-sided SUB device was assessed to be intact and flushed easily from the kidney to the urinary bladder. Focused abdominal ultrasonography of the urinary tract revealed fluid around the right kidney, which was surrounded by hyperechoic retroperitoneal fat. The right renal pelvis was decompressed to 0.7 cm in the transverse plane. Hyperechoic fat and fluid were also visualized around the left kidney; the left renal pelvis measured 0.4 cm in the transverse plane, and the left ureter measured up to 0.2 cm in diameter. Echogenic debris was also seen in the tapering aspect of the left ureter. The newly developed left-sided hydronephrosis and hydroureter were presumed to be caused by inflammation surrounding the retroperitoneal mass after surgical manipulation and compression of the left ureter. Medical management with dexamethasone sodium phosphate (0.1 mg/kg [0.045 mg/lb], IV) was initiated, and prazosin treatment was continued (0.25 mg/kg via ET, q 12 h) in attempts to alleviate any ureteral inflammation or spasm, and mannitol was used to improve diuresis and increase scavenging of free radicals associated with possible acute kidney injury (bolus of 0.25 g/kg, IV, over 20 minutes, followed by a CRI at 1 mg/kg/min, IV).

Results of histologic analysis of the biopsy sample were still pending 48 hours after surgery; ultrasonography at this time revealed persistent left renal pelvis dilation with a measurement of 4.5 mm in the transverse plane (Figure 2). Progressive azotemia (BUN concentration, 111 mg/dL; serum creatinine concentration, 9.5 mg/dL) and hyperkalemia (serum potassium concentration, 6.7 mmol/L; reference range, 3.7 to 5.2 mmol/L) were present, and the patient was anuric, suggesting failure of right renal function with a fully patent SUB device on that side. A second surgery was performed to place an SUB device for the left kidney and fully resect the retroperitoneal mass. Surgical preparation and anesthetic monitoring were performed as previously described. Laparotomy was performed with a ventral approach through the same incision. The left kidney was isolated; the left ureter was observed to be dilated. After retroperitoneal perinephric fat dissection, a 22-gauge catheter was inserted through the caudolateral aspect of the left kidney into the renal pelvis for pyelocentesis and pyeloureterography. The contrast agent (sterile iodinated contrast medium, diluted 1:1 in sterile saline [0.9% NaCl] solution) was seen to stop at the level of the retroperitoneal mass. A 0.018-inch, angle-tipped hydrophilic guide wiree was inserted through the catheter into the renal pelvis and then into the lumen at the proximal aspect of the ureter. The catheter was removed, and an 18-gauge IV catheter was advanced over the guidewire. Then the 0.018-inch guidewire was removed, and a 0.035-inch angle-tipped hydrophilic guidewiree was advanced through the 18-gauge catheter and into the ureter. Next, the nephrostomy catheter, with the locking string removed, was advanced over the wire to terminate in the proximal part of the dilated ureter. This was done to help minimize potential trauma to the renal pelvis because it was small in size. The polyethylene terephthalate cuff of the catheter was secured to the renal capsule with cyanoacrylate gluef as previously described. The urinary bladder catheter was placed in a standard manner lateral to the right-sided urinary bladder catheter. The nephroureterostomy and cystostomy tubes were then connected with the subcutaneous shunting port lateral to the midline incision. The port and catheters were then leak tested, and a digital subtraction contrast evaluation was performed to confirm patency (Figure 2).

Figure 2—
Figure 2—

Perioperative diagnostic images of the same cat as in Figure 1. A—Ultrasonographic image (transverse plane) of the left kidney revealing dilation of the renal pelvis 48 hours after surgery for placement of an SUB device for the contralateral kidney and biopsy of the retroperitoneal mass in Figure 1. Mild hydronephrosis is present (renal pelvis measures 4.5 mm). B—Ventrodorsal fluoroscopic image obtained following placement of a second SUB device. Lt = Left.

Citation: Journal of the American Veterinary Medical Association 253, 9; 10.2460/javma.253.9.1169

Next, the previously biopsied retroperitoneal mass was visually examined within the mesocolon; both left and right ureters were seen to traverse the mass with the right ureter in the center and the left ureter along the left lateral margin. This mass was immediately ventral to the aorta and vena cava. Blunt dissection with right-angle forceps and a handheld cautery unitg was performed to isolate the mass. Both ureters were ligated proximally at the mid ureter and distally near the urinary bladder and then transected. The mass was removed without hemorrhage or other complications and submitted for histologic examination. The abdomen was closed routinely, and the patient recovered from anesthesia uneventfully.

Postoperative treatments included maropitant (1 mg/kg, IV, q 24 h), pantoprazole (1 mg/kg, IV, q 24 h), oxymorphone (0.025 mg/kg/h [0.01 mg/lb/h], IV by CRI), and metoclopramide (2 mg/kg/d, IV, by CRI). Progressive anemia (PCV, 17% [reference range, 28.2% to 52.7%]; serum total protein concentration, 6.4 g/dL [reference range, 6.3 to 8.8 g/dL]) was detected 2 days after surgery, and a packed RBC transfusion (10 mL/kg) was performed. Serial serum biochemical tests for renal function showed improvements in azotemia over 48 to 72 hours after surgery, with serum creatinine concentration decreasing to approximately the presurgical value (3.4 mg/dL) prior to discharge. The patient was discharged from the hospital 4 days after surgery. Prescribed treatments included mirtazapine (0.75 mg/kg [0.34 mg/lb], via ET, q 72 h), omeprazole (1 mg/kg, via ET, q 24 h), maropitant (1 mg/kg, via ET, q 24 h), and buprenorphine (0.01 mg/kg, transmucosally, q 8 to 12 h); provision of a renal care cat foodc was advised. The ET was removed at the time of the recheck examination and suture removal 2 weeks after surgery.

A neuroendocrine carcinoma was diagnosed on histologic analysis of the retroperitoneal mass. The tumor had poor demarcation with infiltration of the surrounding fat. Islands and packets of neoplastic cells were separated by fine to moderate fibrovascular stroma (Figure 3). The cells were described as polygonal to elongated and contained small to moderate amounts of eosinophilic cytoplasm with occasional fine vacuolation, oval nuclei with coarsely stippled to ropy chromatin, and 1 to 2 small nucleoli. Mild to occasional moderate anisocytosis and anisokaryosis were also observed in the cell population, and the mitotic index was 10 mitotic figures/10 hpf. Immunohistochemical staining was performedh to assess for epithelial (pancytokeratin clone AE1-AE3),i mesenchymal (vimentin),j and neuroendocrine (synaptophysink and chromograninl A) markers (Figure 4). There was diffuse positive cytoplasmic immunoreactivity to synaptophysin and chromogranin A, strong cytoplasmic immunoreactivity in numerous cells for vimentin, and no immunoreactivity for pancytokeratin AE-AE3. The results confirmed the lesion was a neuroendocrine tumor and ruled out metastatic carcinoma and granulosa cell tumor. The final interpretation was retroperitoneal neuroendocrine carcinoma with incomplete margins, most consistent with a malignant paraganglioma.

Figure 3—
Figure 3—

Photomicrograph of a section of the retroperitoneal mass in Figure 1. An infiltrative proliferation of neoplastic cells arranged in islands and packets is evident. H&E stain; bar = 100 μm. Inset—In a higher-magnification image, mitotic figures (arrow) are seen. H&E stain; bar = 20 μm.

Citation: Journal of the American Veterinary Medical Association 253, 9; 10.2460/javma.253.9.1169

Figure 4—
Figure 4—

Photomicrograph obtained after immunohistochemical analysis of the mass in Figure 1 shows diffuse strong cytoplasmic immunoreactivity of the entire neoplastic population for synaptophysin and chromogranin A (brown) and moderate to strong immunoreactivity for cytokeratin AE1-AE3 (blue). Results are indicative of a neuroendocrine carcinoma tissue type. Staining of the sample for vimentin had negative results. Immunohistochemical stain; bar = 50 μm. On the basis of anatomic location and histopathologic findings, a diagnosis of neuroendocrine carcinoma was made. Courtesy of IDEXX. Copyright © 2018, IDEXX Laboratories, Inc. Used with permission.

Citation: Journal of the American Veterinary Medical Association 253, 9; 10.2460/javma.253.9.1169

The cat continued to do well after discharge, with appetite and urination reported as normal on recheck examination 1 week after hospital discharge; focused ultrasonographic evaluation of both renal pelvises revealing improvement in size, compared with that at the time of obstruction for the right kidney (0.8 cm); and decreased dilation for the left kidney relative to the last measurement (< 0.2 cm) in the previously described planes. Three weeks after discharge, the cat was returned to the hospital because of an acute history of vomiting and inappetence. On physical examination, the patient's hydration status appeared normal, and no abnormalities were detected. Focused ultrasonographic examination at that time showed a further decrease in right renal pelvis dilation in the transverse plane (0.4 cm), with no change in the measurement for the contralateral renal pelvis (< 0.2 cm). Hematologic evaluation revealed decreased serum creatinine (3.4 mg/dL) and BUN (46 mg/dL) concentrations, improved PCV (34%) and serum total protein concentration (8.0 g/dL), and serum electrolyte (sodium, potassium, and ionized calcium) concentrations within respective reference ranges. In-house cytologic assessment of a urine sample from the SUB device revealed no evidence of microorganisms or inflammatory cells. The patient was administered maropitant (1 mg/kg, SC) and released to the owners. The owners were instructed to administer maropitant (1 mg/kg, PO, q 24 h) and mirtazapine (0.75 mg/kg, PO, q 24 h), monitor the cat, and contact the clinicians if clinical signs appeared to worsen at home. The cat improved at home and was reported to have increased appetite with no further vomiting noted.

Consultation with the oncology department was pursued, and the owner declined further diagnostic tests, staging, and treatment with chemotherapy. Two months after surgery, the cat's body weight was stable (4.94 kg [10.9 lb]), and physical examination results were unremarkable other than the 2 subcutaneous ports palpable on the ventral abdominal wall. Azotemia was persistent (serum creatinine and BUN concentrations, 3.4 and 66 mg/dL, respectively), with a serum symmetric dimethylarginine (commonly described as SDMA) concentration of 18 μg/dL (reference range, 0 to 14 μg/dL). Results of a CBC were unremarkable. The owners were feeding the recommended food and also administering metronidazole (10 mg/kg, PO, q 12 h) and probiotic supplements to address intermittent diarrhea.

On recheck examinations 4 and 8 months after surgery, serum creatinine concentrations were 3.0 and 2.9 mg/dL, respectively, and BUN values were 76 and 73 mg/dL, respectively. Focused ultrasonography of the renal pelvises revealed similar mild pyelectasia (measurements of the right and left renal pelvises in the transverse plane were 0.7 and 0.64 cm, respectively). The SUB devices were flushed without difficulty, and aerobic microbial culture of a urine sample had negative results. The patient's appetite reportedly had improved.

The cat was reevaluated 9 months later because of urination outside of the litter box. The owners reported the urine was malodorous, but no signs of pollakiuria, stranguria, or hematuria were seen. Both SUB devices flushed normally. Results of a urinalysis revealed inactive sediment, and urine culture results were negative for aerobic bacterial growth. The inappropriate urination resolved within 1 week after the examination. Fourteen months after surgery, the patient was reportedly doing well with follow-up visits scheduled at 6-month intervals. Clinicopathologic findings included serum creatinine and BUN concentrations of 3.2 and 61 mg/dL, respectively, and a serum symmetric dimethylarginine concentration of 25 μg/dL; renal pelvis dilation was considered lessened (in transverse plane; 0.3 and 0.0 mm for the right and left renal pelvises, respectively) on ultrasonographic examination, and both SUB devices were considered patent on the basis of flushing (Figure 5).

Figure 5—
Figure 5—

Ultrasonographic images of the same cat as in Figure 1 obtained 14 months after bilateral SUB device placement. A—An image of the right kidney (transverse plane) shows a marked decrease in renal pelvis diameter, compared with that prior to SUB placement. B—An image of the left kidney (transverse plane) shows the SUB catheter traversing the renal parenchyma (arrow); there is no evidence of renal pelvis dilation. C—An image of the urinary bladder shows 1 of 2 straight bladder catheters (arrow) where it enters the lumen at the apex.

Citation: Journal of the American Veterinary Medical Association 253, 9; 10.2460/javma.253.9.1169

Discussion

Paragangliomas are extra-adrenal tumors of embryonic neural crest chromaffin cell origin.4 These tumors can arise from the vagal nerve, adrenal medulla, neuroendocrine organs of the autonomic nervous system and paraganglia of chemoreceptors, and other ganglia throughout the thorax, peritoneum, and retroperitoneum.5 Paragangliomas are rarely reported in human medicine, with an incidence of 2 to 5 patients/million/y.6 Reported symptoms in human patients with paragangliomas and pheochromocytomas are secondary to excessive release of catecholamine neurotransmitters into the circulation and include headaches, heart palpitations, anxiety, vomiting, and sweating.7 In people, paragangliomas most commonly develop in a chromaffin body alongside the abdominal aorta in the infrarenal region known as the organ of Zuckerlandl.8 Although there are concentrations of paraganglia ventrolateral to the descending aorta, such as the adrenal glands and caudal mesenteric artery,9 paraganglia in dogs are most commonly found in the aortic carotid bodies.10 In cats, the incidence and anatomic location of paragangliomas are poorly characterized overall. Reported paraganglioma sites in felids have included the caudal equina (in a domestic cat)11 and retroperitoneal space (in a cougar [Puma concolor]).12 The tumors can be functional or nonfunctional, and this status can often be distinguished by the patient's history, vital signs, and physiologic response to surgical manipulation (eg, hypertension or cardiac arrhythmias),13 similar to that described in the patient of this report. Definitive diagnosis requires biopsy with histologic analysis including immunohistochemical staining for chromogranin, synaptophysin, and neuron-specific enolase.14 Characterization and grading of these tumors can play a role in prognosis because lower expression of chromogranin A has been reported in higher-grade paragangliomas,15 which typically have greater metastatic potential than lower-grade paragangliomas.16 Complications and causes of death in human patients with paragangliomas are reportedly most commonly associated with hemodynamic events such as hypertensive crises and surgical intervention.7

The cat of the present report developed ureteral obstruction and azotemia because of the location and invasiveness of a retroperitoneal paraganglioma. Surgical manipulation of the mass, which involved both ureters but was causing unilateral (right-sided) obstruction, resulted in obstruction of the left ureter and was associated with oliguria and severe acute progression of the preexisting azotemia and progressive hyperkalemia. The most common causes of feline ureteral obstructions identified in a literature review17 included ureterolithiasis, ureteral stricture (up to 32% of cats), dried solidified blood (approx 5% to 8%), and trigonal tumors affecting the ureterovesicular junction (< 1%). Ureteral obstruction resulting from a retroperitoneal tumor, as in our patient, appears to be uncommon, and excision of the mass necessitated ureteral ligation and resection and urinary flow diversion. Placement of the 2 SUB devices allowed for surgical excision of the mass with distal ureteral resection, ureteral diversion, and resolution of the obstruction in an expedited manner.

A thorough diagnostic evaluation (serum biochemical evaluation, urinalysis, urine culture, and diagnostic imaging) aids in the diagnosis of a ureteral obstruction, which is associated with a combination of renal pelvis dilation (> 2 mm) and concurrent hydroureter.3 The obstructive lesion is often not visualized by standard imaging methods, and when this is the case, a stricture, tumor, or dried solidified blood should be considered the most likely cause.3

Medical management is initially recommended for normokalemic patients that are nonoliguric and nonanuric. Treatments in cats can include aggressive fluid therapy (5 to 7 mL/kg/h [2.3 to 3.2 mL/lb/h], IV) for 24 to 48 hours, diuretic administration (mannitol, 0.25 to 0.5 g/kg [0.114 to 0.23 g/lb], IV as a bolus over 30 minutes, followed by a CRI of 1 mg/kg/min, IV), α-adrenergic receptor antagonism (prazosin, 0.25 to 0.5 mg/cat, PO, q 12 h), and antimicrobial administration, when appropriate.18 Medical treatment is most successful for ureterolith-induced obstructions and was reported to benefit 7 of 52 (13%) of patients in 1 study.19 However, when medical management of ureteral obstruction fails, alternative intervention is often required. Because of the high reported morbidity and mortality rates associated with more invasive surgical treatments such as neoureterocystostomy, other interventional techniques have been developed including nephrostomy tubes,17 ureteral stents,17 and SUB devices.20,21 Given the unknown prognosis in the cat of this report, which had invasive neoplasia involving both ureters and severe azotemia, the option previously found to have the lowest associated morbidity and mortality rates, as well as the shortest surgical times,3 was chosen. In cats, according the American College of Veterinary Internal Medicine consensus statement and published short-term and long-term outcomes, compared with those following alternative approaches, placement of an SUB device is considered the treatment of choice in this situation.18 The SUB device placed in our patient was comprised of the previously described locking loop nephrostomy catheter, multifenestrated cystostomy catheter, and metallic shunting port for placement outside of the abdominal wall in the subcutaneous space to allow for fluid drainage, sample collection, and flushing of the device.

The authors elected to advance the left nephrostomy tube into the proximal aspect of the ureter because of the minimal renal pelvis dilation and appreciable ureteral dilation. This is commonly considered in the authors' practice when the renal pelvis measurement is < 5 to 8 mm in the transverse plane as a means of avoiding renal pelvis trauma during coiling of the locking loop pigtail nephrostomy tube.

Complications associated with placement of the described SUB device in dogs and cats have been previously reported.3,22 A recent study22 in cats identified worsening azotemia, device leakage, kinking of catheters, and blood clot development in small numbers of patients; perioperative death was uncommon. Long-term complications include device occlusion from mineralization (40/165 [24%]), with device replacement required in 21 of 165 (12.7%) patients.3 Chronic urinary tract infections have been reported in 10 of 122 (8%) of these patients, with dysuria in 8 of 133 (6%).23 The only factor found to be associated with survival time was serum creatinine concentration 3 months after surgery, and survival time did not differ from that for other cats with chronic kidney disease of similar International Renal Interest Society stage at that time (overall median, 827 days).24

To the authors' knowledge, this is the first clinical report of retroperitoneal paraganglioma in a domestic cat and the first report of tumor resection necessitating ureter removal and the use of SUB devices. Bilateral placement of SUB devices in this patient allowed for aggressive resection with a good short- and long-term (> 426 days) outcomes. Further staging was not pursued by the owner, and the metastatic potential of paragangliomas in cats is presently unknown. Future investigation into the common anatomic locations of paragangliomas in cats and dogs, as well as potential diagnostic features such as urine metanephrine concentrations and possible prognostic factors, could be considered as more cases are recognized.

Acknowledgments

No external funding was provided for this report.

Drs. Berent and Weisse are consultants for Norfolk Vet Products, the company that makes and sells the SUB device.

The authors thank Dr. Elizabeth Appleman for contributions to the case and Dr. Taryn Donovan for providing photomicrographs of H&E-stained slides.

ABBREVIATIONS

CRI

Continuous rate infusion

ET

Esophagostomy tube

SUB

Subcutaneous ureteral bypass

Footnotes

a.

Norfolk Vet Products, Skokie, Ill.

b.

Monocryl suture, Ethicon LLC, Johnson & Johnson, Somerville, NJ.

c.

Hill's Prescription Diet Feline k/d, Hill's Pet Nutrition Inc, Topeka, Kan.

d.

Pedialyte, Abbott Laboratories Inc, Abbott Park, Ill.

e.

Weasel Wire, Infiniti Medical LLC, Menlo Park, Calif.

f.

GLUture Topical Adhesive, Abbott Laboratories, Abbott Park, Ill.

g.

Ligasure, Covidien, Medtronic, Minneapolis, Minn.

h.

IDEXX Laboratories pathology services, IDEXX Laboratories Inc, Westbrook, Me.

i.

Mouse anti-human cytokeratin clone AE1/AE3, Dako North America Inc, Carpenteria, Calif.

j.

Mouse anti-vimentin antibody, Dako North America Inc, Carpenteria, Calif.

k.

Mouse anti-human synaptophysin, Dako North America Inc, Carpenteria, Calif.

l.

Mouse anti-chromogranin A antibody, Biocare Medical Inc, Pacheco, Calif.

References

  • 1. Matoon JS, Nyland TG. Distal ureters, urinary bladder, and urethra. In: Small animal diagnostic ultrasound. 3rd ed. St Louis: Elsevier-Saunders, 2015;569580.

    • Search Google Scholar
    • Export Citation
  • 2. Lee HK, Kim YJ, Jeong JU, et al. Desmopressin improves platelet dysfunction measured by in vitro closure time in uremic patients. Nephron Clin Pract 2010;114:c248c252.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3. Berent AC. Interventional radiology of the urinary tract. Vet Clin North Am Small Anim Pract 2016;46:567596.

  • 4. Lam AK. Update on paragangliomas and pheochromocytomas. Turk Patoloji Derg 2015;31(suppl 1):105112.

  • 5. Rizzo SA, Newman SJ, Hecht S, et al. Malignant mediastinal extra-adrenal paraganglioma with spinal cord invasion in a dog. J Vet Diagn Invest 2008;20:372375.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6. Kirmani S, Young WF. Hereditary paraganglioma-phaeochro-mocytoma syndromes. In: Adam MP, Ardinger HH, Pagon RA et al, eds. GeneReviews. Seattle, Wash: University of Washington, 1993. Available at: www.ncbi.nlm.nih.gov/books/NBK1548/. Accessed Jan 1, 2017.

    • Search Google Scholar
    • Export Citation
  • 7. Kumar S, Choudhary GR, Singh S, et al. Spectrum of retroperitoneal and genitourinary paraganglioma: experience at a North Indian tertiary center. Cent European J Urol 2015;68:421427.

    • Search Google Scholar
    • Export Citation
  • 8. Hayes WS, Davidson AJ, Grimley PM, et al. Extraadrenal retroperitoneal paraganglioma: clinical, pathologic, and CT findings. AJR Am J Roentgenol 1990;155:12471250.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9. Mascorro JA, Yates RD. The anatomical distribution and morphology of extraadrenal chromaffin tissue (abdominal paraganglia) in the dog. Tissue Cell 1977;9:447460.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 10. Capen CC. Endocrine glands. In: Maxie G, ed. Jubb, Kennedy, and Palmer's pathology of domestic animals. 5th ed. Philadelphia: Saunders Ltd, 2005;325428.

    • Search Google Scholar
    • Export Citation
  • 11. Davis WP, Watson GL, Koehler LK, et al. Malignant cauda equina paraganglioma in a cat. Vet Pathol 1997;34:243246.

  • 12. Duhamelle A, Langlois I, Pey P, et al. Malignant paraganglioma in a cougar (Puma concolor). J Zoo Wildl Med 2014;45:994998.

  • 13. Weiss SW, Goldblum JR. Paraganglioma. In: Enzinger and Weiss's soft tissue tumors. 5th ed. Philadelphia: Mosby-Elsevier, 2008;9891015.

    • Search Google Scholar
    • Export Citation
  • 14. Burke A, Virmani R. Benign tumors of neural or smooth muscle origin. In: Atlas of tumor pathology. 3rd series. Washington, DC: Armed Forces Institute of Pathology, 1996;105109.

    • Search Google Scholar
    • Export Citation
  • 15. Brown PJ, Rema A, Gartner F. Immunohistochemical characteristics of canine aortic and carotid body tumours. J Vet Med A Physiol Pathol Clin Med 2003;50:140144.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16. Aresu L, Tursi M, Iussich S, et al. Use of S-100 and chromogranin A antibodies as immunohistochemical markers on detection of malignancy in aortic body tumors in dog. J Vet Med Sci 2006;68:12291233.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 17. Berent AC. Ureteral obstructions in dogs and cats: a review of traditional and new interventional diagnostic therapeutic options. J Vet Emerg Crit Care (San Antonio) 2011;21:86103.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18. Lulich JP, Berent AC, Adams LG, et al. ACVIM small animal consensus recommendations on the treatment and prevention of uroliths in dogs and cats. J Vet Intern Med 2016;30:15641574.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 19. Kyles AE, Hardie EM, Wooden BG, et al. Management and outcome of cats with ureteral calculi: 153 cases (1984–2002). J Am Vet Med Assoc 2005;226:937944.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 20. Cray M, Berent AC, Weisse CW, et al. Treatment of pyonephrosis with a subcutaneous ureteral bypass device in four cats. J Am Vet Med Assoc 2018;252:744753.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 21. Steinhaus J, Berent AC, Weisse C, et al. Clinical presentation and outcome of cats with circumcaval ureters associated with a ureteral obstruction. J Vet Intern Med 2015;29:6370.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 22. Berent AC, Weisse CW, Bagley DH, et al. Use of a subcutaneous ureteral bypass device for treatment of benign ureteral obstructions in cats: 174 ureters in 134 cats (2009–2015). J Am Vet Med Assoc 2018;253:in press.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 23. Livet V, Pillard P, Goy-Thollot I. Placement of subcutaneous ureteral bypasses without fluoroscopic guidance in cats with ureteral obstruction: 19 cases (2014–2016). J Feline Med Surg 2017;19:10301039.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 24. Horowitz C, Berent A, Weisse C. Predictors of outcome for cats with ureteral obstructions after interventional management using ureteral stents or a subcutaneous ureteral bypass device. J Feline Med Surg 2013;15:10521062.

    • Crossref
    • Search Google Scholar
    • Export Citation
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