Lymphocytic adenohypophysitis mimicking a pituitary macroadenoma

A 24-year-old woman developed headache and rapidly progressive visual disturbances during the last trimester of her first pregnancy. Magnetic resonance tomography (MRI) of the brain documented an intra- and suprasellar mass lesion. For preservation of vision, transsphenoidal microsurgical decompression was performed. Immediately postoperatively, visual acuity improved and hemianopia resolved. Histological examination yielded the diagnosis of primary lymphocytic adenohypophysitis. This is a rare inflammatory pituitary disease. There are no typical clinical, laboratory, or radiological findings that allow precise preoperative diagnosis. Even though this autoimmune disorder is principally steroid-responsive, an improvement of visual disturbances under steroid therapy cannot be predicted. Therefore, surgery is justified not only to establish the diagnosis, but also to restore vision by decompression of the optic nerves and the chiasm.