Li Y, et al. - This research ascertained if some unclassified renal cell carcinomas (RCCs) in children and young adults characterized by predominantly eosinophilic cytoplasm exhibited an association with the succinate dehydrogenase (SDH)-deficient RCC, fumarate hydratase (FH)-deficient RCC, or eosinophilic solid and cystic (ESC) RCC. The findings recommended that pathologists ought to exhibit low threshold for performing FH, SDHB, and CK20 immunohistochemistry (IHC) when confronted with unclassified eosinophilic RCC or “oncocytoma” in young patients.