Context:Isolated central diabetes insipidus (CDI) can be the first manifestation of Langerhans cell histiocytosis (LCH), creating diagnostic dilemmas such as dysgerminoma and other inflammatory lesions.

Method:In 2010, the French national LCH registry had enrolled 1236 LCH patients under 18 yr of age. Isolated CDI was the initial presentation of LCH in 26 patients. We reviewed their clinical and magnetic resonance imaging (MRI) features.

Results:Median age at the diagnosis of CDI was 9.6 yr (1.8-16.3), and median follow-up after CDI diagnosis was 9.9 yr (3.5-26.6). In addition to CDI, two patients had visual field defects, four had secondary amenorrhea, and 11 had anterior pituitary deficiency. Cerebral imaging (including computed tomography in two cases), performed in 22 patients within 3 months of CDI diagnosis, showed pituitary stalk thickening in 14 patients, which was moderate (3.0-7 mm) in nine cases and marked (>7 mm) in five cases. In eight cases, the lesion extended to the floor of the third ventricle. One child with LCH presented with a mild enlarged sellar content. During follow-up, 22 patients developed extrapituitary involvement, mainly of bone (n = 15), lung (n = 9), and skin (n = 9). Pituitary biopsy was performed in eight cases and was conclusive in six cases.

Conclusions:Pituitary stalk thickening can be observed in LCH as well as lesions extending to the floor of the third ventricle. In all cases but one, the intrasellar content was not enlarged. Long-term follow-up with close attention to bone, skin, and lung disorders may lead to the diagnosis of LCH.