Isolated tumorous Langerhans cell histiocytosis of the brainstem: A diagnostic and therapeutic challenge

Langerhans cell histiocytosis (LCH) of the CNS is a rare entity, known to involve primarily the hypothalamicpituitary region, with the clinical hallmark of diabetes insipidus. There have been a few reports of CNS LCH involving the brainstem as intraparenchymal enhancing lesions, but this has never been the presenting complaint of LCH. The authors report on a 7-year-old boy who presented with right cerebellopontine syndrome, in whom a well-defined, solid, enhancing lesion in the brainstem was diagnosed. Clinicoradiological differential diagnosis included glioma and tuberculosis. Biopsy revealed atypical histiocytes positive for CD68, CD1a, and S100 protein; these are the diagnostic features of LCH on histopathological examination. The rapid growth of the lesion was controlled with a chemotherapeutic regimen of cladribine.