Endocrine Abstracts

Hypophysitis is classified according to the anatomic location of pituitary involvement and the cause (primary or secondary forms). The primary forms are characterized by an idiopathic inflammatory process confined to the pituitary gland, while the secondary forms are triggered by a definite etiology. Recently, as a secondary form of hypophysitis, an immune-mediated paraneoplastic syndrome defined as paraneoplastic autoimmune hypophysitis has been reported. This novel clinical entity, paraneoplastic autoimmune hypophysitis consists of several conditions such as anti-PIT-1 hypophysitis and a part of isolated ACTH deficiency and immune checkpoint inhibitor-related hypophysitis with common underlying mechanisms, in which an ectopic pituitary antigen expression in the complicated tumor evoked autoimmunity against pituitary-specific antigens, resulting in hypophysitis and exhibiting the injury of specific anterior pituitary cells by cytotoxic T cells. These conditions can explain at least in part, the underlying mechanisms of acquired specific pituitary hormone deficiencies. In addition, it is important to apply a comprehensive discipline of onco-immuno-endocrinology to understand the pathophysiology and this approach, the expansion and application of immune-mediated paraneoplastic syndrome to endocrine diseases may give a new clue to understand pathophysiology of the autoimmunity against endocrine organs. In this lecture, the process and lessons from the journey to encounter this novel concept will be discussed.