Objective      To investigate the MRI manifestations of intracranial lesions associated with Langerhans cell histiocytosis (LCH) in children.       Methods      Fifteen cases of LCH confirmed by surgery pathology or puncture biopsy were reviewed. Eleven patients were males

and 4 females

with age ranged from 1 to 13 years old. Plain and contrast enhanced MR imaging of head and pituitary were performed in all patients. The location

morphology

signal and enhanced patterns of the intracranial lesions were observed and analyzed.       Results      The most common intracranial finding

was the hypothalamic-pituitary involvement which was demonstrated in 10 patients (66.7%)

including absence of normally high signal on T

1

WI in the posterior pituitary gland and thickening and abnormal contrast enhancement of the pituitary stalk. Dural mass was detected in 2 cases

and choroid-plexus mass was detected in 1 case. The masses were characterized by iso- or slightly hypo-intensity on T

1

WI and hypo-intensity on T

2

WI

with marked enhancement after administration of gadolinium. Brain parenchymal lesions were detected in 5 cases

in which 3 accompanied with hypothalamic-pituitary lesions. The parenchymal lesions mainly involved the cerebellar dentate nucleus and basal ganglia

and showed symmetrically patchy hypo-intensity on T

1

WI and hyper-intensity on T

2

WI

with no contrast enhancement.       Conclusion      The intracranial lesions of LCH varies in region

morphology and signal patterns. The hypothalamic-pituitary involvement is more commonly encountered. Hypo-intensity on T

2

WI and marked enhancement are MRI features of extra-axial mass of LCH.