A 42-year-old woman with a 6-year history of diabetes insipidus and progressive hypersomnolence presented with visual loss. Neuroimaging showed infiltration in the hypothalamus, the optic nerve, and the chiasm, as well as multiple lesions in other areas of the brain parenchyma. Biopsy showed Langerhans cell histiocytosis. This is an unusual presentation of Langerhans cell histiocytosis, involving the visual pathways without manifestations outside of the central nervous system. The differential diagnosis and the magnetic resonance imaging findings will be discussed.