RESUMO
A 3-year-old girl presented with polydipsia and polyuria for last 2 years. Her fluid intake was 7~8 L/day, and urinalysis showed low osmolality and specific gravity. Central diabetes insipidus (DI) was diagnosed by a water deprivation test. Intranasal 1-desamino-8-D-arginine vasopressin relieved her symptoms and normalized urinary concentrations. A T1-weighted MRI scan revealed a symmetrical thickening of the central part of the pituitary stalk. Six months after the diagnosis of central DI, she developed papular skin lesions on her forehead. The lesions were surgically removed, and histologically classified as Langerhans cell histiocytosis (LCH). We concluded that thickening of the central part of the pituitary stalk might represent the first manifestation of LCH clinically presenting with central DI. In children with central DI, special attention should be paid to the appearance of the pituitary stalk using MRI for the various manifestations of LCH in the central nervous system.