While hypophysitis is more commonly associated with anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) agents, its occurrence following anti-programmed cell death protein 1 (PD-1) inhibitors like nivolumab remains rare and diagnostically challenging due to nonspecific symptoms and frequent absence of radiographic abnormalities. The gene discussed is CTLA4; the disease is hypophysitis.