Primary Diffuse Large B Cell Lymphoma in Kidney with Involvement of Central Nervous System and Heart in a Siamese Cat

Background: Lymphoma is the most common neoplasia in cats and usually happens in middle-aged males of European breeds, FeLV-positive test is also observed in 25% to 50% of these cases. The diagnostic of renal lymphoma is based on clinical signs, the diagnosis is based on clinical signs associated with additional tests. Histological an immunohistochemical evaluations allows the classifcation which can provide prognostic information. Central nervous system metastasis is frequently reported, but lingual and lung lobe extension were also reported. Here, we report a case of renal lymphoma with systemic involvement of heart and CNS in a cat. Case: A 3-year-old male Siamese cat presented with weight loss, emesis, anorexia, polydipsia and polyuria for at least 3 weeks. The clinical parameters were stable, but presenting pale mucosal membrane and also severe dehydration. Complete blood count and chemistry profle revealed anemia and severe azotemia. On abdominal palpation, bilateral renomegaly and irregular contours of both kidneys were also detected. The kidneys were enlarged and had irregular contours on palpation, confrmed by abdominal ultrasonography, that revealed kidneys with markedly irregular contours, and the presence of fluid with high cellularity between cortical and renal capsule (capsular fluid). An aspiration citology by fne-needle from the capsular fluid guided by ultrasound was collected and sent to cytological analysis, which suggested lymphoma. The aspirate was moderately cellular and consisted of large round cells with distinct, scant, basophilic cytoplasm, round nuclei with dense chromatin, inconspicuous nucleoli, and large amount of naked cells. On the second day of treatment the cat presented a cardiopulmonary arrest not responsive to cardiopulmonary cerebral resuscitation, died, and the owner authorized the necropsy, allowing the renal biopsy showing that the same neoplastic cells presented in kidneys were also seen in heart and central nervous system, suggesting the occurrence of primary renal lymphoma with involvement of to these tissues, and the diagnosis was high grade diffuse large cell lymphoma. And also histopathological exam diagnosed high grade diffuse large cell lymphoma. Discussion: The patient died, and the post-mortem histological analysis confrmed the diagnosis of primary diffuse large B cell lymphoma in kidney with systemic involvement of heart and central nervous system (CNS). Lymphoma is the most common renal tumor in cats, howev