Late-Onset Hypophysitis Induced by Nivolumab in Advanced Esophageal Squamous Cell Carcinoma.

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment, particularly in advanced esophageal squamous cell carcinoma (ESCC), where nivolumab has demonstrated significant survival benefits. However, these therapies may precipitate immune-related adverse events (irAEs), including endocrine disorders such as hypophysitis. 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.