Linfoma renal primário em cão / Primary kidney lymphoma in a dog

ABSTRACT

Background: Lymphoma is a malignant lymphoid tumor originating in the lymph nodes or other solid organs and comprises90% of all hematopoietic tumors in dogs. However, primary kidney lymphoma is rare and is associated with nonspecificclinical signs. Tumor invasion in both kidneys can cause severe clinical signs due to renal failure, complicating the patient’streatment and prognosis. The aim of this case was to report the case of a dog affected by bilateral primary kidney lymphoma. In addition, to characterize the clinical and histopathological presentation due to the intense morphological changes.Case A 5-year-old male Poodle dog was admitted showing apathy and emesis for 5 days. On physical examination, thedog showed 10% of dehydration, reddish oral mucous membranes, poor body condition (score 1/5), uremic breath, andpain in the kidney area. Complementary tests revealed severe low white blood cells count, high BUN levels, high levels ofpotassium, calcium, and phosphorus (serum biochemistry). Abdominal ultrasound showed bilateral kidney enlargement.Fine needle aspiration of the mass (guided by ultrasound) revealed round cell tumor. Radiographs showed no alterations.The dog died due to his poor condition and necropsy was performed. On post-mortem examination, the kidneys were bothenlarged, pale, and with an irregular subcapsular surface. The histopathological diagnostic was primary renal lymphoma.Immunohistochemical staining revealed that neoplastic cells were strongly positive for anti CD20 and PAX5, while negative for CD3, supporting the diagnosis of B-cell lymphoma.Discussion: The diagnosis was based on clinical, complementary tests, fine needle aspiration, histopathological andimmunohistochemical findings. In dogs, primary kidney tumors are uncommon and usually malignant. The presence ofvomiting, uremic breath, dehydration, weight loss, and erosive and ulcerative lesions on the tongue (uremic glossitis)...