Commentary on Adrenal wash-out CT: moderate diagnostic value in distinguishing benign from malignant masses

The increasing use of cross-sectional imaging, mainly CT, results in an accelerating number of incidental findings, for instance of adrenal tumours. Although most 'adrenal incidentalomas' are benign, it is important to identify the malignant and the hormone producing (functional) tumours. For a small fraction of adrenal incidentalomas, the diagnosis is apparent on imaging, but the large majority requires radiological characterisation. To this end, a previous joint European Society of Endocrinology and European Network for the Study of Adrenal Tumours publication in this jounal, recommends CT measurements of the native (non-contrast) tumour attenuation ≤10 Hounsfield units, consistent with a lipid-rich benign adrenocortical adenoma, and imaging at least 6 months apart, on which unchanged tumour size implies a benign tumour. Because of weak evidence, calculation of CT contrast medium washout was not recommended as a means for tumour characterisation, but this technique has nevertheless still been applied in several countries. The recent article by Schloetelburg et al. in this journal is important because, in the largest study to date, the authors confirm that calculation of CT contrast medium washout with established thresholds is insufficient to reliably characterise adrenal tumours. Their results are therefore expected to impact the management of these patients.