Author response: Papillary RCC and oncocytoma: Longer follow-up reported

Dear Editor, The clinical significance of papillary renal cell carcinoma (RCC) within renal oncocytoma remains unclear. The tumour volume, tumour subtype and presence of recurrence or metastasis during the follow-up period may be helpful to understand the natural history and the clinical significance of these tumours. Therefore, the current tumour free follow-up period of the case reported by Floyd et al contributes to the literature. However, there is a possibility that their case may be accepted as a papillary adenoma within a renal oncocytoma because of the small diameters of tumour (1.5 mm).¹ Papillary adenomas and papillary RCC are histologically and cytogenetically identical, and are currently seperated based on size. Tumours ≤5 mm in maximum dimension are believed to have a limited growth potential and are designated as adenomas.^{2, 3} Thus, our case stil can be accepted as with the longest tumour free follow-up period concerning papillary RCC within renal oncocytoma with the largest papillary RCC diameter (15 mm).⁴