ESPE Abstracts

Introduction: Central diabetes insipidus (CDI) is a rare disorder in children. The etiology of CDI in childhood is heterogeneous: tumors or surgery in the hypothalamic-pituitary region, head trauma, vascular and inflammatory diseases. Neuroimaging plays an important role in the differential diagnosis of CDI in children and adolescents. The MRI may detect brain malformations, but also is the gold standard when evaluating the sellar-suprasellar region in CDI.

Case presentation: We report a 12-year old girl who presented in Endocrinology Department for progressive weight gain in the last years and oligomenorrhea. On endocrine examination she had obesity, goiter and poliuro-polidipsic syndrome (ingestion of 10 liters liquids /24h and diuresis of 10 liters/24h). The laboratory assessment revealed low urine gravity (1004 g/24h, normal range 1005-1030 g/24h), autoimmune thyroiditis and normal function of the anterior pituitary. The water deprivation-vasopressin test confirmed CDI. The diagnosis was further supported by serum copeptin measurement (<1.2 pmol/l, reference range 1.5-15.3) and desmopressin treatment was initiated. Imaging examination showed a pituitary microadenoma (3/3.5/3 mm) and thickening of the pituitary stalk (3.4/3.8 mm). Thus, infiltrative diseases were considered in the differential diagnosis. Bone X-ray showed multiple lytic bone lesions in the left femoral bone and skull. Langerhans cell histiocytosis (LCH) was confirmed by pathology of the biopsy specimen from the skull lesion. Systemic therapy containing steroids and vinblastine induced remission. After 6 months, she was reevaluated in our Pediatric Endocrinology Department. Hormonal measurements showed secondary adrenal insufficiency (8 am serum cortisol<1 mg/d, ACTH 1.65 pg/ml; normal range 4.2-22 mg/dl, 7.2-63.3 pg/ml), side-effect of the systemic glucocorticoids she had received for LCH. At this time, pituitary MRI identified a regression of the pituitary stalk thickening (2.2/2.6 mm), but an increase in the size of the pituitary microadenoma (6/5/4.5 mm). Nevertheless, diabetes insipidus persisted with normal secretion of the anterior pituitary hormones.

Conclusion: Isolated CDI can be the first manifestation of LCH. LCH is a rare disease in children, with variable clinical spectrum including localized and disseminated forms mostly occurring in children. Pituitary insufficiency may occur in the context of the disease or secondary to systemic treatment. The most common type of hormone deficiency in children with LCH is growth hormone (GH) deficiency, followed by ACTH deficiency. For this reason an adequate follow-up to monitor for disease progression, relapse, and sequelae is recommended.

Keywords: Langerhans cell histiocytosis, children, diabetes insipidus