Endocrine Abstracts

Incidental adrenal lesions are a common finding on radiological studies with a prevalence of 3-10% depending on the age of the population. The investigation, risk stratification and surveillance of adrenal incidentalomas has an opportunity cost in resource-finite healthcare systems. The current approach advocated in the 2023 European Society for Endocrinology (ESE) clinical practice guidelines relies on the doctrine that adrenal adenomas remain benign and do not transform to higher grade disease. The guidelines recommend characterisation with unenhanced adrenal protocol CT, or MRI, in addition to clinical and biochemical assessment for hormonal excess. Following this, patients with non-functioning homogenous adrenal lesions <4 cm that are ≤10HU can be discharged without further imaging or follow up. However, reports of patients developing adrenocortical carcinoma several years after initial diagnosis with an adrenal adenoma have been emerging. A retrospective review of adrenal nodules reviewed at Cambridge University Hospitals from 2018-2024 identified three patients seen with apparent transformation to adrenocortical carcinoma (ACC) several years after formal characterisation of a benign adrenocortical adenoma. These three cases account for 0.4% of all incidental adrenal nodule cases reviewed during this period. All three patients had non-functioning adenomas with size <4 cm and radiodensity <10HU at diagnosis, which showed stability on interval imaging performed for other reasons over a 7, 12 and 12 year period respectively prior to rapid transformation and subsequent histological confirmation of of ACC. These patients would have met the criteria for discharge under the existing ESE recommendations. Adenoma to carcinoma transition, with the progressive accumulation of driver mutations, is well described for other cancers such as colorectal carcinoma. The possibility of a similar scenario has been proposed in the adrenal, but remains unproven. These additional case reports give further credence to this hypothesis and validate the need for ongoing work to identify the underlying molecular mechanisms.