ENO2 and paraganglioma: The confirmed diagnosis of paraganglioma mainly depends on histopathological and immunohistochemical findings as following (i) the classic Zellballen pattern composed of chief cells and sustentacular cells within the tumor; (ii) the chief cells showed positive staining to NSE, CgA, Syn, and negative for CK; and (iii) the sustentacular cells showed positive staining to S-100 or GFAP.