Background: Central diabetes insipidus (DIC) is usually the final result of lesions affecting the hypothalamicneurohypophyseal system, for the children, germinoma is the main reason. The MRI aspect is often limited to thickness pituitary stalk with loss of hyperintensity of the neurohypophysis.
Objective and hypotheses: Thickening of pituitary stalk is suggestive of germinoma, the clinical picture is dominated by a DIC (90%), associated to hypopituitarism (60%), his natural history is unpredictable, he should always be considered. The diagnosis is easy if the βhCG rate is high, or if there is a pineal localization, but in most cases, these tests are normal and the MRI does not differentiate germinoma from other causes thickening pituitary stalk (histiocytosis, sarcoidosis or lymphocytic hypophysitis.
Method: A 15-year-old boy, referred to our clinic for his growing delay and polyuriapolydipsia syndrome appeared 6 months earlier (estimated 5 l/day). Physical exam: weight=P3, size <P3, Tanner step 1. He shows signs of GH and corticotropin deficiencies. No intracranial tumor syndrome.
Results: (i) Hormonal test: DIC with hypocortisolism, hypogonadism and GH deficiency. (ii) Pituitary MRI: pituitary salk enlargement (6 mm), loss of T1 hyperintensity of the posterior pituitary. (iii) Biologic and morphologic analysis discards a secreting germinoma, histiocytosis X and sarcoidosis assumption.
Conclusion: MRI report is the diagnosis key of isolated large pituitary stalk, with other clinical clues; but still a long monitoring each 36 months, without histological evidence, can be suggested; checking for germinoma or histiocytosis existence, especially in child case. There are no good imaging predictors for hypopituitarism, making clinical and hormonal evaluation of all patients with pituitary stalk lesion crucial.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology