The histology and growth kinetics of canine renal oncocytoma.

A renal oncocytoma was diagnosed in a 10-year-old English springer spaniel with a 5-month history of anorexia, vomiting and weight loss. The tumour, which was localized to the kidney, was treated by simple nephrectomy and the dog made a full recovery. Histologically, the tumour consisted of cells with abundant eosinophilic cytoplasm forming acini and alveolar nests set within a loose fibrovascular stroma. The results of cell kinetic studies (AgNOR score 2.68, PCNA index 5.2%) were comparable with findings reported for benign human renal tumours. This appears to be the first reported case of renal oncocytoma in a dog.