Watch the mass, save the gland (radiation therapy perhaps later)

This 35-year-old woman presented with central diabetes insipidus and a lesion of approximately 1.5 cm located in the pituitary stalk. The neuroradiologist provided the differential diagnoses of langerhans cell histiocytosis (LCH), sarcoidosis, germ cell tumor, and Rathke’s cleft cyst. In addition, other rare inflammatory lesions, including IgG4-related disease and lymphocytic infundibuloneurohypophysitis, should be considered. To help formulate the diagnosis, additional investigations include a bone scan, a positron emission tomography scan, and spine magnetic resonance imaging, as well as measurement of cerebral spinal fluid angiotensin converting enzyme, antipituitary antibodies, and high serum IgG4 concentration.