Endocrine Abstracts

An important issue for all endocrinologists involved in management of non-functioning pituitary adenomas (NFAs) not treated surgically at initial presentation is the frequency and duration of follow-up neuroimaging. Previous studies have described tumour enlargement in less than 15% of microadenomas (<1cm diameter) with macroadenomas (1cm diameter or more) showing a greater propensity for growth. With improvements in neuroimaging techniques we felt that it was timely to revisit this issue.

We performed a retrospective study assessing potential growth of NFAs managed conservatively following initial presentation. All tumours were confirmed to be functionally inactive by baseline pituitary function testing. MRI imaging (1.0 or 1.5 Tesla) was undertaken at least annually.

Fifteen patients were followed up (9/15 were women). Of the whole group 5 (33%) had microadenomas (mean+/-se height 5.4+/-1.2mm) and 10 (67%) macroadenomas (mean height 11.5+/-2.0mm) at presentation. None had optic chiasmal compression at presentation. 4/15 patients were found to be hypopituitary at baseline requiring 1 (1/15) or 3 or more (3/15) hormone replacements. The age range at presentation was 15 to 74. Mean (se) duration of follow-up was 4 years+/-11 months.

Of the 3/15 tumours that increased in size, all went on to transsphenoidal resection and 2/3 (follow-up periods 12 and 14 months respectively) of these had expanded to involve the chiasm. All adenomas that increased in size were 9mm or more in height at initial presentation. No tumour of 7mm or less in maximum height increased in size. 3/15 (20%) adenomas decreased in size and 4/15 (27%) underwent cystic degeneration over the follow-up period.

The lack of evidence of tumour growth for NFAs 7mm or less in maximum height raises the issue of the appropriateness of repeat MRIscans in such individuals. For larger adenomas serial scanning is mandatory but the time intervals between scans can be increased with increasing duration of follow-up.