Neurodegeneration in the course of Langerhans cell histiocytosis.

Cerebral involvement in the course of Langerhans cell histiocytosis has been described especially in children. It is mainly characterized by hypothalamic-pituitary functional deficit, due to granuloma growth. Here we describe a rare case of adult-onset histiocytosis developing a neurodegenerative disease resembling multiple system atrophy. The patient we describe here started suffering from subtle personality changes which progressed to a severe neurological syndrome 2 years after the diagnosis of histiocytosis. Twenty years before she developed a diabetes insipidus, without any apparent cause. Brain MRI scans at the time of neurodegeneration revealed slight signal alterations at the cerebellum, especially involving the dentate nuclei and the white matter. Despite being rare, histiocytosis should be considered in adult patients with cerebellar abnormalities and/or with unexplained diabetes insipidus to rapidly discern and treat histiocytosis before the onset of its neurodegenerative, untreatable phase.