• Clinical Presentation:
Langerhan cell histiocytosis is the nonmalignant proliferation of histiocytic granulomas in tissue. This disease is rarely seen in adults, but is common in children. CNS manifestations are associated with the form of the disease known as Hand-Schuller-Christian disease. Symptoms include hypothalamic/pituitary dysfunction such as diabetes insipidus, visual disturbances, and ataxia.

• Pathology:
Atypical Langerhan cells stain for S-100 protein and contain Birbeck granules. These cause acute bone lesions in the cranium and CNS manifestations in the pituitary infundibulum, hypothalamus, leptomeninges, cranial nerves, and the brain parenchyma.

• Image Findings:
MRI shows infundibular thickening or a focal hypothalamic mass, isointense on both T1WI and T2WI which enhances homogeneously. There may be absence of the posterior pituitary or enhancement of cranial nerves and leptomeninges.