Langerhans cell histiocytosis with disequilibrium.

Langerhans cell histiocytosis (LCH) is a very rare disease in which granulation tissue forms in various organs and the central nervous system (CNS) due to monoclonal proliferation of Langerhans cells. Some patients develop ataxia, tremor, or neurodegenerative abnormalities (such as personality changes and mental deterioration) several years after the onset as the late effects of LCH. We report a case of a 4-year-old boy with LCH, showing speech disorder, truncal ataxia and a wide-based gait with abnormal findings of central nervous system in CT and MRI image. The results of auditory brain stem response revealed a conduction block in the auditory conduction pathway, suggesting an axonopathy of the brain stem. Disequilibrium may be due to brainstem dysfunction associated with paraneoplastic syndrome because an anti-GluRε2 antibody was seen. Paraneoplastic syndrome is a neuropathy induced through an autoimmune mechanism caused by an antibody directed against the nervous system. Neuro-otological examination is helpful for the assessment of CNS neurodegeneration associated with LCH.