OBJECTIVETo evaluate the role of brain magnetic resonance imaging (MRI) and tumor markers in the cerebral spinal fluid (CSF) and serum in the diagnosis and treatment of intracranial germinoma in children.

METHODSTotally 5 children (3 girls and 2 boys) who were treated in our hospital between January 2009 and December 2010 due to central diabetes insipidus. All patients received contrast-enhanced brain MRI at presentation and during each follow-up: meanwhile, their anterior pituitary hormones and tumor markers including human chorionic gonadotropin (hCG) and alpha fetoprotein (AFP) were also determined.

RESULTSThree patients presented without prior evaluation, and two patients were referred to our hospital due to exaggerated disease of unknown cause. Their ages at presentation ranged from 8 years to 12 years 1 month, and the duration of symptoms at presentation was between 1 month to 78 months. All of them had polyuria and polydipsia at presentation. Except one child, the other 4 patients had growth retardation and failure in initiation of puberty. Although the growth rate and puberty development were normal during the 2-year follow-up for the excepted child, all child experienced anterior pituitary hypofunction and an increased concentration of plasma prolactin after the lesion became enlarged. Three patients had cerebral hernia, which presented in 18, 24, and 78 months, respectively. In three patients, brain MRI at presentation showed isolated pituitary stalk thickening, which further developed into massive tumor in the hypothalamus pituitary region 18-22 months later; in the remaining two patients, large brain tumor was found via MRI at their first presentations. In all five patients, the posterior pituitary gland (bright spot) disappeared on T1-weighted MRI images. CSF hCG elevated in all five patients, and serum hCG increased in four patients; the level of hCG varied with the mass size of tumor. Serum and CSF AFP increased in only one patient.

CONCLUSIONSPatients with idiopathic central diabetes insipidus must be closely followed to identify the etiology, especially when anterior pituitary hormone deficiencies are detected. For patients with normal brain MRI results or simply isolated pituitary stalk thickening at presentation, the changes of serial contrast-enhanced brain MRI should be observed during follow-up to ensure the early detection of an evolving occult hypothalamic-stalk lesion. Determination of CSF hCG at the first presentation may be useful, because an increased CSF level of hCG precedes MRI abnormalities.