[Germinoma: a rare cerebral tumor causing central diabetes insipidus in childhood]. / Il germinoma: un raro tumore cerebrale causa di diabete insipido centrale in età infantile.

Germinoma represents 7.8% of cerebral tumors in pediatric age and 50-65% of germ cell cerebral tumors. Generally it is a definite lesion of the pineal gland or suprasellar region, frequently occurring in the first three decades of life. Clinical presentation depends on tumor localization. Pineal lesions generally determine symptoms due to the compression of cerebral structures, causing Parinaud syndrome, while hypothalamic lesions are often characterized by diabetes insipidus, hypopituitarism and visual defects. In the absence of these classic signs and symptoms, however, the diagnosis of germinoma can be difficult. We presented the case of an 8-year-old boy, referred to our clinic for polyuria and polydipsia. Hormonal evaluations demonstrated central diabetes insipidus (CDI), with normal anterior pituitary function. Magnetic resonance imaging (MRI) showed a lack of posterior pituitary gland and partial pituitary stalk enlargement. The patient started therapy with desmopressin (Minirin) with good hydro-electrolytic balance. During follow-up the pituitary function became insufficient with low growth velocity. A second MRI demonstrated a bifocal lesion with dyshomogeneous and cystic appearance, suggesting the diagnosis of germinoma. On the basis of this case report we would like to point out the importance of an early diagnosis in order to improve the prognosis of the disease and the necessity of a careful follow-up of these patients.

[Polyuria and polydipsia in a 5 year-old child: diagnostic problems]. / Esordio di poliuria e polidipsia in una bambina di 5 anni: le problematiche della diagnosi differenziale.

Polyuria and polydipsia could be present in three groups of diseases; polydipsia psicogena characterized by an excessive water intake, central diabetes insipidus (CDI) with a defect in the production of AVP and nephrogenic diabetes insipidus in which a defect in the renal response to vasopressin is present. In particular, CDI can be caused by lesions like germinoma and craniopharyngioma, Langerhans'cell histiocytosis, inflammatory, autoimmune and vascular diseases, trauma resulting from surgery or an accident; and in rare cases, genetic defects in the synthesis of vasopressin that are inherited as autosomal dominant or X-linked recessive traits. However, 30% to 50% of cases are considered idiopathic. Nevertheless, 30-50% of cases is considered idiopathic. Here we present the case of a 5.5 year-old female patient, referred to our Department of Endocrinology Surgery for polyuria and polydipsia. Hormonal tests demonstrated the presence of CDI with normal anterior pituitary function. Magnetic resonance imaging showed the lack of hyperintensity of posterior pituitary. Pituitary stalk was median and of regular volume. Diagnosis of CDI has been confirmed and therapy has been started with desmopressin (Minirin) 0.2 mg/die. During the follow-up the patient was in good conditions, presented an adequate hydro-electrolytic balance and normal growth velocity. Anterior pituitary function was normal and MR remained stable. This case report highlights problems concerning differential diagnosis and the importance of a careful follow-up which must involve the whole family.

Role of ghrelin in the regulation of appetite in children.

Ghrelin, the new recently discovered hormone, is a 28 amino-acid acylated peptide predominantly produced by the stomach characterized by a strong GH-releasing activity mediated by the hypothalamic-pituitary GH secretagogues (GHSs) receptors. Ghrelin and GHSs, acting on central and peripheral receptors, exert other actions such as stimulation of ACTH and prolactin secretion, influence on insulin secretion and glucose metabolism, orexigenic effect and modulatory activity on the neuroendocrine and metabolic response to starvation, influence on exocrine gastro-entero-pancreatic functions, cardiovascular activities and modulation of cell proliferation and apoptosis. The wide spectrum of ghrelin action requires further studies to provide critical information on the role of ghrelin and the potential perspectives of its analogues in the clinical practice. This point is of particular interest in the field of pediatric endocrinology and metabolism because the ghrelin story started focusing on GH deficiency and is now extending to aspects that once again are of major relevance such as obesity and eating disorders, regulation of the hypothalamus-pituitary-adrenal and gonadal axis. More studies are needed to evaluate the real impact of ghrelin in different non endocrine processes and the possible use of ghrelin analogues in different diseases condition.