Computed tomographic findings of primary renal tumors in dogs and cats

Primary renal tumor is uncommon in dogs and cats, with few previous computed tomography (CT) reports. Previous studies have reported that contrast-enhancing CT is helpful in differentiating the type of renal tumors. This study aimed to describe CT findings of renal tumors in dogs and cats and identify contrast-enhancing pattern according to 3 post-contrast phases. In this retrospective study, the following CT findings were recorded for each patient: (1) renal tumor involvement, (2) enhancement pattern, (3) vascular invasion, (4) presence of lymphadenopathy and organ metastasis, (5) presence of mineralization, and (6) attenuation values of renal tumors on pre- and post-contrast corticomedullary, nephrographic and excretory phase images. Eight dogs and 2 cats met the inclusion criteria, of which 7 had renal cell carcinoma, 2 had lymphoma and one had nephroblastoma. Renal cell carcinomas tended to show heterogeneous and progressive contrast enhancement, unilateral renal involvement and relatively high incidence of lymphadenopathy. Renal lymphomas showed heterogeneous and progressive contrast enhancement and bilateral renal involvement. Nephroblastoma showed heterogeneous and plateau pattern of contrast enhancement and unilateral renal involvement. Findings from the current study support that CT with triphasic contrast study is helpful in renal tumor characterization and vascular invasion and metastasis evaluation. Further large-scale studies are necessary to examine the association between CT and histopathological findings.