RESUMEN
Lymphocytic infundibuloneurohypphysitis(LINH) is a newly classified disorder and proposed as a common cause of idiopathic central diabetes insipidus. It is characterized by thickening of the infundibulum and/or pituitary stalk and absence of high signal in the neurohypophysis in sellar MRI and the microscopic findings of diffuse lymphocytic infiltration within the neurohypophysis. A 12year-old boy presented polyuria and headache. The result of water deprivation test was compatible with central diabetes insipidus. Brain MRI showed thickening of the pituitary stalk and loss of high signal in the neurohypophysis. Craniotomy and excisional bi6opsy was done under the impression of pituitary tumor. Microscopically, neurohypophysis showed dense lymphocytic infiltration and no malignant cells. Six months after the operation, the previously thickened pituitary stalk and neurohypophysis appeared normal in follow-up MRI.