Langerhans cell histiocytosis and the central nervous system in childhood: evolution and prognostic factors. Results of a collaborative study.

This retrospective study detailed clinical and radiologic involvement of the central nervous system related to Langerhans cell histiocytosis in 18 French children. We excluded cases of isolated hypothalamic-pituitary dysfunction or spinal involvement. Cerebellar symptoms were the most common clinical symptoms. Two different patterns of magnetic resonance or computed tomographic images were identified: demyelination and gliosis or atrophy, described as degenerative lesions, mostly located in the cerebellum in 10 children, or tumor-like lesions occurring in any part of the brain in 13 children. Six children had both types of lesion. The clinical cerebellar syndrome correlated with the specific imaging pattern suggestive of a cerebellar degenerative lesion, which did not show any changes after treatment. As suggested by this study and previous clinical and histologic reports, it is believed that brain involvement in the course of Langerhans cell histiocytosis might arise from different disease mechanisms: primary histiocyte proliferation and secondary atrophy or demyelination and gliosis of unknown origin. Treatment consequently should be adapted to the supposed mechanism of the lesion.