Eight cases of autoimmune hypophysitis in a single centre – an underestimated disease?

Autoimmune hypophysitis is a very rare disease and the diagnosis is mostly achieved by excluding other causes. Hypophysitis can cause pituitary expansion and hypopituitarism closely mimicking the features of a pituitary adenoma. It should be considered in the differential diagnosis of any nonsecreting pituitary mass. Between 1992 and 2005 we observed eight patients (five women [age: mean, 33.4 years; range, 19–42 years], three men [age: mean, 38 years; range, 10–73 years]) with the diagnosis of autoimmune hypophysitis. No relevant previous diseases or gynaecological disorders were reported. Systemic granulomateous diseases were excluded, and the diagnosis of autoimmune hypophysitis was based on the typical morphological lesions of the pituitary gland and stalk, as well as on the follow-up examinations (1 to 10 years). The patients were evaluated for their pituitary functions. The leading symptom was polyuria/polydipsia (n=5) or headache (n=3). One patient presented with additional idiopathic vitiligo, another patient with Hashimoto thyroiditis. All five patients with diabetes insipidus showed a thickening of the pituitary stalk, whereas patients with insufficiency of the adenohypophysis presented a homogenous enhancement of the entire gland in MRI imaging. In the follow-up, five patients had a normal pituitary MRI scan, however, in three patients the pathological MRI image persisted. None of the patients showed an improvement of their pituitary function, despite reversibility of MRI findings in 5/8 patients. High-dose glucocorticoid therapy was given in two cases without any clinical changes.