MRI features of neurodegenerative Langerhans cell histiocytosis.

CNS complications of LCH include "space occupying" lesions corresponding to histiocytic granulomas and "neurodegenerative" presentation (ND-LCH) characterized by a progressive cerebellar ataxia. Studies analyzing specifically the MRI presentation of ND-LCH are scarce. We present here the MRIs of 13 patients registered as isolated ND-LCH. Posterior fossa was involved in 12 patients (92%), showing a symmetrical T2 hyperintensity of the cerebellar white matter areas in seven cases with a circumscribed T1 hyperintensity of the dentate nuclei in five cases, definite hyperintense T2 areas in the adjacent pontine tegmentum white matter in nine cases associated with a hyperintensity of the pontine pyramidal tracts in four cases. A cerebellar atrophy was noted in eight cases. The supratentorial region was involved in 11 patients, showing T2 hyperintense lesions in the cerebral white matter in eight cases and a discrete symmetrical T1 hyperintense signal in the globus pallidus in eight patients. A diffuse cortical atrophy was present in three cases and a marked focal atrophy of the corpus callosum in three cases. This series allows us to establish a not previously reported evocative semeiologic MR presentation to precisely orientate to the diagnosis of the pure neurodegenerative form of LCH.