The Natural History of Silent Corticotroph Adenomas: A Tertiary Referral Centre Experience

G. Deb, R Nair, N Mendoza, N Martin, Imperial College Healthcare NHS Trust, London, UK.

Background: Non-functioning pituitary adenomas (NFAs) are tumours which do not secrete pituitary hormones. Silent corticotroph adenomas (SCAs) are an NFA subtype which are immunoreactive for adrenocorticotropic hormone (ACTH) but present without clinical or biochemical evidence of hypercortisolism. There is debate as to whether SCAs follow a more aggressive clinical course in comparison to other NFAs.

Aims: To compare the clinical and radiological characteristics of SCAs with other pituitary NFAs.

Methods: A retrospective analysis was performed of patients who had undergone trans-sphenoidal surgery at Charing Cross Hospital, Imperial College Healthcare NHS Trust. Electronic patient records were reviewed for comparison of pre-operative and post-operative characteristics between SCA and NFA patients.

Results: 14 SCA patients were identified and a cohort of 127 NFA patients were studied for comparison. Whilst sex was not significantly different between the two groups, SCAs presented at a younger age in comparison to NFA patients (mean SEM; 58.0 1.15 [NFA] vs. 48.1 3.95 years [SCA], p<0.01). Presenting symptoms and mode of presentation were comparable between SCA and NFA patients. Radiological characteristics, including cavernous sinus invasion and suprasellar extension, were also similar. Post-operatively, there was no statistical difference between the proportion of tumours that exhibited a Ki-67 of less than or more than 3% between the NFA and SCA cases. However, SCA patients exhibited an increased recurrence rate compared to the NFA group (18.1% [NFA] vs. 50.0% [SCA], p=0.01) and were more likely to recur multiple times i.e. were recorded to have recurred 2 or more times in the duration of this study (0% [NFA] vs. 21.4% [SCA], p=0.001). Kaplan Meier analysis showed SCA patients exhibit faster progression to tumour recurrence (p<0.005). Radiotherapy was required by a significantly greater proportion of the SCA patients than NFAs (13.4% [NFA] vs. 50% [SCA], p<0.005).

Conclusions: SCA patients presented at a younger age and demonstrated an increased propensity to pituitary tumour recurrence compared to those patients with NFAs. This study supports closer post-operative surveillance and early discussion for adjuvant radiotherapy in patients with a SCA.