A case of renal cell carcinoma found through skin metastasis in a dog

Abstract A French bulldog presenting with a skin mass was found to have an enlarged left kidney on a preoperative systemic examination. The left kidney and skin mass were surgically removed. Histopathological and immunohistochemical analyses identified the enlarged left kidney as renal cell carcinoma, with the skin mass likely representing a metastatic lesion. This case was unusual, as the asymptomatic renal cell carcinoma was identified alongside a metastatic skin mass, which was the only clinical indication of the disease. Additionally, the outcomes of toceranib administered as adjuvant therapy following nephrectomy were less favourable than those documented in previous studies. This suggests that renal cell carcinoma with skin metastasis might be associated with a poor prognosis. This report highlights that skin metastasis in dogs can lead to the diagnosis of renal cell carcinoma, as well as that it is important not to overlook skin metastatic lesions, which may indicate an adverse prognosis.