Langerhans cell histiocytosis (LCH) is a systemic disease associated with the proliferation and accumulation (usually in granulomas) of Langerhans cells in various tissues.

The term gait disturbance can refer to any disruption of the ability to walk. In general, this can refer to neurological diseases but also fractures or other sources of pain that is triggered upon walking. However, in the current context gait disturbance refers to difficulty walking on the basis of a neurological or muscular disease.