October's Case of the Month

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Renal Mass in a Juvenile Dog

Dr. Anne Desrochers

Patient Information:

Age: 3 months
Gender: Female
Species: Canine
Breed: Mix

History: 

Pet presented for routine vaccination. Abdominal mass palpated on physical examination. Bloodwork and abdominal radiographs not performed.

Image Interpretation:

Left kidney: a large ill-defined mixed echogenicity mass containing a few anechoic fluid-filled cavitated areas was seen originating from the cranial pole of the left kidney. The mass measured at least 7.7x8.8cm in diameter (too big to obtained accurate measurements) and vascular signal was obtained when assessing the lesion with color flow Doppler. The renal pelvis was moderately dilated measuring 8.2mm.

Additional Testing:

Fine-needle biopsies of the mass were obtained. Cytology results revealed: based on a low number of cellular aggregates comprised of polygonal cells with large oval nuclei, an undifferentiated tumor is suspected with 70% confidence. Top differentials include nephroblastoma (seems most likely given the patient's age) or a possible carcinoma. Recommend biopsy/histopathology of this poorly exfoliating lesion to obtain a definitive diagnosis.


Diagnosis:

Neproblastoma is a rare tumor and is most often found in juvenile dogs. It is a malignancy that arises from the embryonic remnants of the immature kidney. All reports of renal nephroblastoma in dogs less than 1 year of age, treatment with surgery alone or with surgery and adjuvant chemotherapy did not prevent progression of disease and death.


Outcome: 

The patient underwent exploratory surgery for nephrectomy but humane euthanasia was elected during the procedure due to extensive adhesion of the renal tumor to the mesentery and adjacent abdominal organs. Submission for histopathology for definitive diagnosis was not pursued.

Image: Longitudinal view showing the presence of a mass associated with the cranial pole of the left kidney and secondary pyelectasia due to compression of the renal pelvis. Image obtained with a high frequency transducer.

Image: Longitudinal view showing the presence of a mass associated with the cranial pole of the left kidney and secondary pyelectasia due to compression of the renal pelvis. Image obtained with a high frequency transducer.

Image: A dense aggregate of polygonal cells with large oval nuclei.

Image: A dense aggregate of polygonal cells with large oval nuclei.

Special thanks to Dr. Naqi and the staff at Banfield Fairlakes and Dr. Casey LeBlanc DVM, PhD, ACVP (Clinical Pathology) at EasternVetPath for their help with this case.