Gigantism due to growth hormone excess in a boy with optic glioma

True gigantism is rare in early childhood and is usually due to excess GH s ecretion from a pituitary adenoma. We report a case in which the endocrine abnormality is secondary to an optic glioma. Careful endocrine evaluation h as shown that GH peak amplitude was not increased but rather there was fail ure of GH levels to suppress to baseline and a lack of pulsatility. There i s no evidence of a direct secretory role for the tumour and we postulate th at the tumour is affecting GH secretion through an effect on somatostatin t one. Specific tumour therapy is not indicated for this patient in the absen ce of mass effect or visual disturbance. The GH excess is being treated wit h somatostatin analogue (Octreotide) and as he has developed precocious pub erty he is also receiving long acting GnRH analogue (Zoladex). This boy app ears likely to have neurofibromatosis type 1 (NF1) which raises the questio n of subtle GH excess in NF1 patients with tall stature.