Endocrine Abstracts

Autoimmune hypophysitis (AH) is characterized by lymphocytic infiltration and eventually destruction of the pituitary tissue. AH accounts for ~1% of pituitary masses and 0.5% of hypopituitarism. Although it has been recognized as an uncommon pituitary disease, its true frequency is not known but certainly underestimated. AH may affect pre- and post-menopausal women, men and children, but most cases are reported in women during reproductive age. AH may be associated with other autoimmune disorders including Hashimoto’s thyroiditis, pernicious anemia, type 1 diabetes mellitus, Graves’ disease, autoimmune adrenalitis. Based on the anatomical location, several types of AH is described as follows: lymphocytic adenohypophysitis (LAH), in which inflammation is limited to the anterior pituitary and it usually manifests during pregnancy, lymphocytic infundibuloneurohypophysitis (LINH), in which male and female are equally affected, and lymphocytic panhypophysitis (LPH). Diabetes insipidus may be seen especially in patients with LINH. Diffuse thickening of the pituitary stalk, enlarged pituitary gland associated with homogeneous contrast enhancement, suprasellar expansion especially tongue-like extension and loss of neurohypophyseal ‘bright spot’ in the imaging studies are helpful radiological findings in the diagnosis of AH. In spite of normal MRI findings, varying degrees of hypopituitarism may exist in patients with AH. Recent data suggest that AH may be associated with empty sella which may be the final outcome of AH. Empty sella is a common radiological feature of Sheehan’s syndrome, for this reason it should be included in the differential diagnosis of AH. The diagnosis of LH is difficult at least in patients without histopathological findings. Presence of antipituitary antibodies (APA) especially antibodies to pituitary hormone-producing cells may be helpful in the diagnosis of AH. On the other hand, recent data have shown that pituitary autoimmunity may play some role in the development of hypopituitarism seen in patients suffered from traumatic brain injury (TBI). Pituitary dysfunction development ratio in TBI has been found to be significantly higher in APA positive patients when compared with APA negative patients.