It is difficult to use immunohistology panels to distinguish between sporadic and BHD-associated renal cell carcinomas (RCCs). Kato et al. (2016) used fluorescent and chromogenic in situ hybridisation (FISH and CISH respectively) to assess the status of chromosome 17q, 2p and 6p in both BHD-associated and sporadic tumours of various histologies. Whilst most of the sporadic chromophobe RCCs were monosomic at 17q, 2p and 6p, the BHD-associated chromophobe RCC and HOCTs were all disomic (apart from one chRCC which was monosomic at 17q). These statistically significant differences identify FISH/CISH analysis at these loci as a novel diagnostic marker of chromophobe RCC tumours associated with BHD. Suspected cases should then be followed up with genetic testing, enabling patients and family members to access appropriate screening.