Langerhans cell histiocytosis of the optic chiasm.

Langerhans cell histiocytosis (LCH) is a rare disease with clonal proliferation of dendritic histiocytes forming a pseudotumoral growth. LCH occurs most frequently in infancy or early childhood. It can present either as a localized self-limiting form or as a diffuse form with multisystem involvement. Herein an unusual case of LCH involving the optic chiasm is presented. To the authors' knowledge, this is the first reported case of LCH presenting with visual disturbance. The clinical, radiological and histopathological findings are discussed.