Endocrine Abstracts

Case history: A 73-year-old female with a background of hypertension presented to the acute physicians with a 4 month history of progressive headaches. The headaches did not have any ‘red flag’ features. A non-contrast CT scan revealed an intrasellar lesion. She was referred to endocrinology for further management. Her history did not suggest hypopituitarism, Cushing syndrome or acromegaly. There were no visual field defects and her eye movements were normal.

Investigations: Biochemical investigations revealed normal sodium, prolactin, IGF-1, FT4 and TSH levels. A Short Synacthen test was also normal. A non-contrast MRI of her pituitary showed a well-defined, 15 mm lesion on the left side of the pituitary fossa of indeterminate signal on both T1 and T2 sequences. An intrasellar aneurysm was suspected, hence the imaging was followed up with a magnetic resonance angiogram. This confirmed an aneurysm of the anterior communicating artery, within the sella.

Results and treatment: The aneurysm was treated endovascularly with a flow diverting stent across the neck of the aneurysm. A follow-up MRI scan 5 months later showed the lesion was now hyperintense on T1 MRI, in keeping with a thrombus within the aneurysm.

Conclusions and points for discussion: Incidentally discovered intrasellar lesions are common, with a prevalence ranging between 1 and 30% in imaging and autopsy series. The differential diagnoses include neoplasia, cysts, inflammatory, infectious or vascular lesions. Intrasellar aneurysms, which mostly originate from the internal carotid artery are rare causes of intrasellar lesions, with a recent systematic review identifying only 40 such lesions in the published literature. Aneurysmal rupture is a presenting feature in 15% of cases. Others present with headaches, visual field deficits or endocrinopathies, of which hyperprolactinaemia or hypogonadism are common. Importantly, 20% of intrasellar aneurysms can coexist with an adenoma. Our patient has done well following her flow diverting stent and her aneurysm is likely to involute within 12–18 months. Intrasellar aneurysms presenting as pituitary lesions deserve a high level of suspicion, as missing these can be catastrophic. Endovascular repair is now the treatment of choice for most of these lesions.