Solid Renal Cell Carcinoma in a Dog

Abstract

Background: Renal cell carcinoma (RCC) is the most important renal neoplasm found in dogs and cats when compared to metastatic or multicentric ones. This malignant epithelial neoplasm affects frequently middle-aged males, whit reserved prognosis. The present study aimed to report a study case about a male dog histologically diagnosed with solid RCC, treated by unilateral nephroureterectomy.

Case: A 8-year-old, male, mixed-breed , castrated dog with 20.4 kg was treated at the “Cães, Gatos & Cia Clinic” in Brusque city, state of Santa Catarina, Brazil. The animal showed acute abdominal pain and hematuria. Abdominal ultrasound (AU), thorax radiograph, complete blood count (CBC), serum biochemistry and urinalysis were also performed. Urinalysis demonstrated brown, turbid and alkaline pH (8) urine, with slightly low density (1,010) containing erythrocytes (> 200,000/mL) and leukocytes (116,000/mL) cells, including degenerated neutrophils and macrophages, and also moderate bacterial flora and few transitional cells. AU revealed a hypoechoic and heterogeneous nodular structure formed by cavitary regions, free fluid and peritonitis areas on the right kidney’s topography were identified too, while radiograph image evidenced a well-defined mass, measuring approximately 8.5 cm. After imaging exams, the exploratory celiotomy executed resulted in the remotion of the malign structure, considering the appropriate safety margin, followed by histopathological examination. The full procedure consisted in the right unilateral nephroureterectomy, and subsequent postoperative care chemotherapy with carboplatin, piroxicam, omega-3 and probiotics supplementation. Neoplastic cells with mantle arrangement were distinguished forming small interspersed groups for thin trabeculae of fibrovascular tissue. These cells exhibited polyhedric shape, distinct cellular boundaries, round or oval central nuclei (loose chromatin with up to 2 small basophilic nucleoli), and a large amount of eosinophilic cytoplasm. Mitotic forms were also observed, moderate pleomorphism and no atypia. These observations were compatible with solid RCC, suggesting immunohistochemical analysis.

Discussion: RCC is a malign and frequent neoplasm in middle-aged male dogs, with nonspecific clinical signs and laboratory test results (CBC and serum biochemistry) making it difficult to diagnose, therefore image exams are essentials to support neoplasia hypothesis. On the other hand, fine needle aspiration, ultrasound-guided or exploratory celiotomy biopsies followed by histopathological examination can also be used; in the present case, the latter was chosen. Furthermore, immunohistochemistry is essential as diagnosis tool to determine RCC cytological or molecular nature. Hence, in cases of unilateral RCC, in which there is no impairment of renal function and metastasis, the treatment is unilateral nephroureterectomy and post-surgical chemotherapy, in addition to palliative care aimed at the patient's welfare. Despite the given instructions offered to the tutor, about immunohistochemistry and chemotherapy importance for patient diagnosis and prognosis, negative response was perceived. As in the present study case, as well as in others, after surgical removal; pursuit of the patient's wellbeing would ensure that the healthy kidney maintained its functions, and also monitor possible metastases emergence. In fact, this and other struggles are faced by veterinarians in Brazil convincing tutors to perform complementary exams and treatments, considered expensive. Such behavior indicates that many patients who could have better and favorable prognosis or longer life span, after being diagnosed and treated for neoplasms, do not have this opportunity.

Keywords: dog, neoplasia, renal cell carcinoma, nephrectomy, chemotherapy.

Título: Carcinoma de células renais sólido em cão

Descritores: cão, neoplasia, carcinoma renal, nefrectomia, quimioterapia.