What Is Your Diagnosis?

Alessandro Zotti Department of Veterinary Clinical Sciences, Radiology Unit, University of Padua, 35020 Legnaro, Padua, Italy.

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Furio Corsi Clinica Veterinaria Montecchia, Via P. Schiavo, 20, Selvazzano Dentro, Padua, Italy.

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Alessandra Ratto I.Z.S. Piemonte, Liguria e Valle d'Aosta, CEROVEC, Piazza Borgo Pila 39, Int. 24, 16129 Genoa, Italy.

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Claudio Petterino Department of Public Health, Comparative Pathology and Veterinary Hygiene, University of Padua, 35020 Legnaro, Padua, Italy.

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History

A 10-year-old 9-kg (19.8-lb) sexually intact male mixed-breed dog was brought to its veterinarian for a routine annual examination and vaccination. The dog's general body condition was good and mental status was bright and responsive; no sign of previous illness was reported by the owner. Abdominal palpation revealed a large mass (approx 10 × 8 × 6 cm), with a firm consistency occupying the craniodorsal portion of the right side of the abdomen. The dog had no signs of pain in response to palpation of the mass.

A moderate neutrophilic leukocytosis was detected on a CBC (82% neutrophils; reference range, 60% to 77% neutrophils). Serum biochemical analysis revealed high serum alkaline phosphatase (112 U/L; reference limit, < 100 U/L) and creatine kinase (241 U/L; reference range, 20 to 150 U/L) activities, a high cholesterol (293 mg/dL; reference range, 140 to 200 mg/dL) concentration, and low glucose (57 mg/dL; reference range, 70 to 110 mg/dL), triglyceride (24 mg/dL; reference range, 40 to 150 mg/dL), and albumin (2.8 mg/dL; reference range, 3 to 5 mg/dL) concentrations. Serum protein electrophoresis revealed low albumin (40.6%; reference range, 53% to 65%) and α1-globulin (1%; reference range, 2% to 5%) fractions and high α2- (19.3%; reference range, 8% to 14%) and β-globulin (21.2%; reference range, 10% to 15%) fractions. The albumin-to-globulin ratio was low (0.68; reference range, 0.79 to 1.35).

A dark brown urine sample was obtained via ultrasound-guided cystocentesis. Urinalysis revealed a urine specific gravity of 1.030 (reference limit, > 1.020) and urine protein concentration of 300 mg/dL (reference range, 0 to 30 mg/dL). Leukocytes and RBCs were observed in the urine sediment. Abdominal ultrasonography was performed (Figure 1).

Figure 1—
Figure 1—

Longitudinal (A) and transverse (B) ultrasonographic images of the abdomen of a 10-year-old 9-kg (19.8-lb) sexually intact male mixed-breed dog with no history or signs of illness evaluated as part of a routine annual examination. Abdominal palpation revealed a large mass in the craniodorsal portion of the right side of the abdomen. Ultrasonographic images were obtained with a 7.5-MHz micro-convex array transducer.

Citation: Journal of the American Veterinary Medical Association 237, 7; 10.2460/javma.237.7.777

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →

Diagnostic Imaging Findings and Interpretation

Severe right-sided renal hydronephrosis and hydro-ureter is evident (Figure 2). An ultrasonographic scan of the retroperitoneal space did not identify a ureterolith or any luminal or extraluminal mass surrounding the ureter. No abnormalities were detected on ultrasonography of the urinary bladder and ureterovesical junction. The primary differential diagnosis was ureteral obstruction of unknown etiology with either pyelonephritis or hemorrhage. To further evaluate for ureter obstruction, the dog was referred for computed tomographic examination.

Figure 2—
Figure 2—

Same ultrasonographic images as in Figure 1. Right-sided severe hydronephrosis and hydroureter are evident; notice the dilated renal pelvis (RP) and ureter (U) and the thin rim of renal parenchyma remaining that is only a few millimeters thick (arrows).

Citation: Journal of the American Veterinary Medical Association 237, 7; 10.2460/javma.237.7.777

An enlarged right kidney (9×7×5 cm) was evident on computed tomographic images (Figure 3). The cranial pole of the kidney was characterized by a grossly dilated pelvis with only a thin rim of renal tissue surrounding a nonenhancing, homogeneous, hypoattenuating content. The caudal pole of the right kidney had a polycystic appearance with similar hypoattenuating content as that of the dilated pelvis and poor peripheral rim enhancement with multiple mineralized foci. The entire ureteral diameter was uniformly dilated (0.8 × 0.65 cm) with fluid content similar to that of the dilated renal pelvis. Both the thickened ureteral wall and the compressed kidney cortex had poor contrast medium enhancement; the absence of contrast medium within both the pelvis and ureteral lumen was consistent with severe hydronephrosis and hydroureter. No enlarged renal or sublumbar lymph nodes were detected. The absence of masses in the retroperitoneal space and absence of calculi or strictures along the ureter and at the ureterovesicular junction were confirmed on computed tomographic examination. Differential diagnoses included primary neoplasia of the kidney extending to the ureter or vice versa (eg, transitional cell carcinoma [TCC], squamous cell carcinoma, undifferentiated tumor, and metastatic tumor), chronic bacterial ureteritis, granulomatous ureteritis, and ureteral polyps.

Figure 3—
Figure 3—

Postcontrast transverse computed tomographic images at the level of the cranial (panel A) and caudal (panel B) poles of the right kidney of the same dog as in Figure 1. Images were obtained by use of third-generation conventional computed tomography with a slice thickness of 5 mm. Notice that the right kidney (RK) is markedly enlarged as a result of a dilated renal pelvis and irregular cystic tissue at the caudal pole (window width, 360 Hounsfield units [HU]; window level, 40 HU). The distance between 2 bars of the vertical scale on the right side of images corresponds to 1 cm. The right ureter (U) is also dilated and the wall is thickened. A = Aorta. CVC = Caudal vena cava. LK = Left kidney. Asterisk = Left ureter.

Citation: Journal of the American Veterinary Medical Association 237, 7; 10.2460/javma.237.7.777

Comments

Surgical excision of the right kidney and ureter was performed. Grossly, the kidney was enlarged. Upon longitudinal sectioning of the kidney, a large cyst-like space filled with dark-red gelatinous material and marked atrophy of the cortex and medulla was found. The renal pelvis had an irregular and papillate-like surface that contained a mass of white tissue with multifocal areas of necrosis and hemorrhage. The ureteropelvic junction was infiltrated by the same type of abnormal tissue. The ureter was markedly thickened throughout its length with an irregular surface, and the lumen was narrowed to completely obstructed by the infiltrating white tissue. A histopathologic diagnosis of TCC of the renal pelvis with infiltration of the ureter was made.

Diagnosis of TCC in the renal pelvis can be challenging. Histologic examination of biopsy tissue specimens is the diagnostic standard1, 2; however, both ultrasonography and computed tomography should be considered as valuable diagnostic tools. In the dog of this report, the use of computed tomography allowed for a more detailed examination of abnormalities in the renal parenchyma and urethra.

The treatment of choice for TCC in the renal pelvis is excision. The prognosis depends on the elimination of the primary lesion; the prognosis is poor when the tumor is metastatic, bilateral, or locally invasive. At 4 months after surgery, the patient continued to be in good condition.

  • 1.

    Dudley RM. What is your diagnosis? J Am Vet Med Assoc 2003; 223: 17311732.

  • 2.

    Militerno G, Bazzo R & Bevilacqua D, et al. Transitional cell carcinoma of the renal pelvis in two dogs. J Vet Med A Physiol Pathol Cin Med 2003; 50: 457459.

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