CA9 and kidney cancer: The differential diagnosis for ONs also includes those benign or malignant renal neoplasms with granular cytoplasm, such as high‐grade RCC (HG‐RCC), eosinophilic variant of clear cell RCC (CCRCC), eosinophilic solid and cystic RCC, eosinophilic vacuolated tumor, fumarate hydratase‐deficient RCC (FH‐dRCC), papillary neoplasm with reverse polarity, TFE3‐rearranged RCC (TFE3‐rRCC), etc. Combined immunostains for CD117, CK7, CK20, AMACR, CA9, FH, GATA3, TFE3, etc. may help to distinguish ONs from these mimics.