Two prepubertal boys without any neurological signs nor diabetes insipidus were studied at age 12 and 15 years (bone age 9 and 12 years) because of declining height velocity. Arginine and insulin failed to induce GH release whereas TRH test results and cortisol response to insulin were normal. Skull radiographies did not show any abnormalities. On CT scan the pituitary stalk was suspected to be abnormal, but only with magnetic resonance imaging (MRI) a small round posterior nodule of the pituitary stalk was clearly demonstrated in both cases. Its qualitative appearance was equal to neurohypophyseal tissue. The lower part of the stalk was reduced to a filament leading to a hypoplastic pituitary gland which seemed to lack the posterior lobe. This suggests that in our patients the neurohypophysis may be located in an ectopic position attached to the pituitary stalk. Biopsy or surgical removal was avoided. The patients responded markedly to hGH therapy. At present, a malformation of the pituitary stalk seems to be a rare cause of GH insufficiency, but it is likely that a more extensive use of MRI for evaluation of apparent idiopathic hypopituitarism may reveal a higher incidence of such anomalies.
展开▼
