Gagel's granuloma (localized Langerhans cell histiocytosis) in the pituitary stalk.

A 46-year-old man with diabetes insipidus, hypothyroidism and hypocortisolism was found to have a tumor of the pituitary stalk. After transsphenoidal resection of the tumor substitution of cortisol and thyroxin was necessary. Pathological examination of the lesion revealed an extremely rare granulomatous infiltration classified as Gagel's granuloma (Langerhans' cell histiocytosis). Pre- and postoperative magnetic resonance imaging (MRI) studies, differential diagnosis and treatment of such lesions are presented.