CTSK and oncocytic neoplasm: listed the value of PAX8, CK7, CK20, CD117, TFE3, CathepsinK, SDH, FH and 2SC antibodies in the differentiation of various “eosinophilic” morphologically confusing renal tumors, such as FH-deficient RCC, SDH-deficient RCC, oncocytoma, eosinophilic solid cystic renal cell carcinoma (ESC-RCC), low-grade oncocytic tumor, (LOT), etc. (9).