Hypothalamic-infundibular histiocytosis: magnetic resonance findings

We report the magnetic resonance imaging (MRI) of a case of Langerhans cell histiocytosis in the pituitary. Isolated central nervous system involvement is uncommon. An eighteen-years old female patient who had an acute onset of central diabetes insipidus because of the Langerhans cell histiocytosis. The MRI evidenced a lesion in the hypothalamic-pituitary axis. The hyperintensity in the posterior pituitary lobe, which is seen in normal subjects on T1-weighted images, was absent. The pituitary stalk was thickened and enhanced homogeneously following contrast administration. During the follow-up, the infundibullar lesion extended to the hypothalamic region and other systemic manifestations appeared. Diagnosis of Langerhans cell histiocytosis was confirmed by lung biopsy. After radiotherapy and chemotherapy, MRI showed regression of the hypothalamic-pituitary lesion. The combination of these findings, although nonspecific of Langerhans cell histiocytosis, should nevertheless prompt further studies, including chest films, bone scanning and temporal bone computerized tomography in order to narrow the differential diagnosis.