In the cases investigated, several neoplasms, previously diagnosed as ccRCC, showed a thyroid-like aspect, characterised by an eosinophilic content cystic-follicular architecture, with negativity for TTF-1 and thyroglobulin and without, as already mentioned, a specific immunohistochemical pattern. The gene discussed is TTF1; the disease is nonpapillary renal cell carcinoma.