SDHB and hyperinsulinemic hypoglycemia, familial, 4: SDH-deficient RCCs were first recognized as a provisional entity by the 2013 International Society of Urological Pathology (ISUP) Vancouver Classification.4 They are rare, with an estimated frequency of 0.05–0.2% amongst all RCCs, and they display distinct clinical, morphologic, and molecular features.5 Furthermore, within this rare RCC group SDH deficiency due to biallelic SDHB loss appears to be most frequent while biallelic SDHA loss has rarely been reported.5,6 Little is known regarding the genomic context of SDH-deficient RCC and how it relates to therapeutic options.