Langerhans cell histiocytosis presenting as a rapidly evolving frontotemporal syndrome.

Langerhans cell histiocytosis (LCH) is a rare disorder in adults which usually manifests with involvement of multiple organ systems, including the central nervous system. We describe an unusual case of biopsy-proven LCH presenting with frontotemporal-dominant cognitive impairment with hypothalamic involvement, along with multisystem disease. We propose that the dementia was probably an immune-mediated process triggered by LCH which responded dramatically to high-dose steroids.