Background: Adrenal incidentalomas are discovered unexpectedly and with increasing frequency on cross-sectional imaging acquired for reasons unrelated to adrenal dysfunction. Whilst the majority are non-functioning, literature suggests there is an increased risk of malignancy for adrenal incidentalomas above 4 cm. American guidelines advising resection of all incidentalomas above 4 cm were established without strong evidence whilst European guidelines adopt a more pragmatic approach.
Aim: This clinical audit was conducted to evaluate the appropriateness of current guidelines by looking at the outcome of non-functional adrenal incidentalomas above 4 cm in a UK hospital over a 9 year period.
Method: A list of all patients discussed in the adrenal MDT from 2009 until 2018 was obtained. Patients identified with non-functional incidentalomas >4 cm were included in the analysis. They were classified into 3 categories at the initial MDT (consensus from endocrinologists and radiologists based on CT appearances) benign, indeterminate and malignant dependent on Hounsfield units, washout studies and presence of aggressive features.
Results: 368 patients discussed at the adrenal MDT of whom 21 (6%) had adenomas >4 cm. These 21 patients were categorised into benign (11 patients, 52%), indeterminate (7, 33%) and malignant (3, 15%). There was no correlation between adenoma size and the three categories. 5 patients in the benign cohort underwent follow up imaging with only 1 increasing in size, insignificantly; the remaining 6 have not re-presented. 3 radiological indeterminate incidentalomas were resected and histologically benign, whilst the remaining 4 were followed up with CT or PET within 18 months with no resultant malignant transformation. Malignant lesions were referred to oncology or surgery for follow up (2 metastasis and 1 lymphoma).
Conclusion: 1. Local UK data supports European guidelines advising pragmatic management of adrenal incidentaloma above 4 cm.
2. Benign lesions do not require routine follow up.
3. Indeterminate lesions require imaging surveillance but are usually benign.