18F-FDG PET in neurodegenerative Langerhans cell histiocytosis : results and potential interest for an early diagnosis of the disease.

Introduction The so called "neurodegenerative Langerhans cell histiocytosis" (ND-LCH) is a rare and severe complication of LCH presenting as a progressive cerebellar ataxia associated with pyramidal tract signs, and cognitive impairment. MRI is the gold standard to investigate CNS lesions of ND-LCH but little is known about functional changes observed in this disease.