IFNG and pheochromocytoma: Prominent staining cells for immunoreactive IFN-γ was observed in 12 out of 35 (34.3%) of the adrenal cortical adenomas, two of four (50%) of the adrenal cortical carcinomas, eight out of 30 (26.7%) of the phaeochromocytomas and 16 out of 60 (26.7%) of the clear cell RCC.