ESPE Abstracts

Background: Pituitary gigantism is a rare condition that occurs due to excessive GH secretion during childhood, usually associated with a pituitary adenoma. We describe a case that required the full spectrum of standard therapeutic options available.

Case report: A 15-year-old boy presented with a 3-year history of intractable occipital headaches and being psychologically distressed by his tall stature (203 cm). He had mild clinical features of GH excess. Investigations: IGF1 markedly elevated (103 nmol/l); basal GH 28 μg/l failed to suppress by oral glucose; testosterone low for pubertal status; impaired cortisol response to Synacthen. MRI scan revealed a sellar/parasellar macroadenoma (17×13 mm), impinging on the posterior optic chiasm, with lateral invasion of the cavernous sinus.

Results: Hydrocortisone replacement was started, together with testosterone (1000 mg/3 monthly i.m.) to accelerate epiphyseal fusion. Octreotide was commenced to control GH excess and promote tumour shrinkage. After 2 months, the headaches persisted and a unilateral upper quadrant visual field defect was apparent. Trans-sphenoidal debulking of the tumour was performed, leaving left parasellar and posterior tumour mass; histology confirmed GH-immunopositive pituitary adenoma. Headaches improved, but GH and IGF1 levels remained elevated, in keeping with residual disease. Pegvisomant treatment was initiated to block GH effect, achieving normalisation of IGF1, and his height stabilised at 205 cm (epiphyses fused). Interval MRI showed residual tumour growth, therefore treatment with Pasireotide was started (a test dose pre-operatively had shown greater suppression of GH than octreotide). The patient is now undergoing radiotherapy, which had initially been deferred at patient’s request to avoid disruption of his academic studies.

Conclusion: Treatment goals for a GH-secreting adenoma with gigantism include limiting final height attainment, normalising GH, replacement of pituitary hormone deficiencies, and definitive tumour control. With unresectable residual tumour, this patient has required multiple therapeutic strategies.