Endocrine Abstracts

Co-existence of a brain tumour (not associated with previous irradiation) and a pituitary adenoma has been rarely described. Astrocytomas have an incidence of <5/100,000 and somototroph adenomas of <4/1,000,000. In astrocytomas, a positive correlation between IGF-I immunoreactivity and histopathological grade/cell proliferation rates have been proposed. Here, we report a case of acromegaly detected incidentally shortly after the diagnosis of an anaplastic astrocytoma.

A 28-year old man presented with seizures. Imaging demonstrated a left frontal lobe lesion and biopsy confirmed an astrocytoma. Four months later, he had further growth of the tumour and he was referred for surgery. The excised specimen showed an anaplastic astrocytoma (grade III). On physical examination by the neurosurgeons, acromegalic features were noted. Further investigations confirmed the diagnosis of acromegaly (nadir GH in OGTT 26.5 mU/L, above normal IGF-I levels, 7 mm pituitary adenoma within the left side of the fossa extending into the cavernous sinus). Given his recent craniotomy and the priority of irradiation of the brain tumour, medical treatment with a somatostatin analogue was considered as the first therapeutic option for the GH hypersecretion. Three months after commencing on lanreotide, the patient has shown significant clinical and biochemical improvement (mean GH 9.62 mU/L, reduction of IGF-I). Further benefit is anticipated following recent increase in the dose of lanreotide making him a candidate for long-term medical therapy with the somatostatin analogue.

This is the first reported case of an anaplastic astrocytoma (not attributed to previous radiotherapy) co-existing with a somatotroph adenoma. Although the presence of both tumours is most likely coincidental, the contribution of the high IGF-I levels to the progress of the astrocytoma can not be excluded.