Computed tomography criteria for discrimination of adrenal adenomas and adrenocortical carcinomas: analysis of the German ACC registry Stephan Petersenn * , Paul-Ajoy Richter 1,* , Thomas Broemel 2 , Christian O Ritter 3 , Timo Deutschbein 4 , Frank-Ulrich Beil 1 , Bruno Allolio 4 , Martin Fassnacht 4,5 and for the German ACC Study Group ENDOC Center for Endocrine Tumors, Altonaer Street 59, 20357 Hamburg, Germany, 1 Department of Internal Medicine, University of Hamburg, Hamburg, Germany, 2 Praenobis Hamburg, Hamburg, Germany, 3 Department of Radiology and 4 Endocrine and Diabetes Unit, Department of Internal Medicine I, University Hospital and 5 Comprehensive Cancer Center Mainfranken, University of Wu ¨ rzburg, Wu ¨ rzburg, Germany * (S Petersenn and P-A Richter contributed equally to this work) Correspondence should be addressed to S Petersenn Email stephan.petersenn@ endoc-med.de Abstract Objective: Thresholds of 2–20 hounsfield units (HU) in unenhanced computed tomography (CT) are suggested to discriminate benign adrenal tumors (BATs) from malignant adrenal tumors. However, these studies included only low numbers of adrenocortical carcinomas (ACCs). This study defines a HU threshold by inclusion of a large cohort of ACCs. Design: Retrospective, blinded, comparative analysis of CT scans from 51 patients with ACCs (30 females, median age 49 years) and 25 patients with BATs (12 females, median age 64 years) diagnosed during the period of 2005–2010 was performed. Methods: Tumor density was evaluated in unenhanced CT by two blinded investigators. Results: Median tumor size was 9 cm (range 2.0–20) for ACCs vs 4 cm (2.0–7.5) for BATs (P!0.0001). In ACCs, the median unenhanced HU value was 34 (range 14–74) in comparison with 5 (K13 to 40)in BATs (P!0.0001). ROC analysis revealed a HU of 21 as threshold with the best diagnostic accuracy (sensitivity 96%, specificity 80%, and AUC 0.89). However, two ACCs that were 5 and 6 cm in size would have been missed. Setting the threshold to 13.9 allowed for 100% sensitivity, but a lower specificity of 68%. Conclusions: This first large study on ACCs confirmed that the vast majority of ACCs have unenhanced HU O21. However, to avoid misdiagnosing an ACC as benign, a threshold of 13 should be used. European Journal of Endocrinology (2015) 172, 415–422 Introduction An incidentally detected adrenal lesion (incidentaloma) is a common finding during abdominal computed tomography (CT). Lesions of 1 cm or larger are reported to occur in up to 5% of patients. Most of these lesions in patients with no known malignancy will prove to be benign. Usually, conventional imaging tries to discrimi- nate benign adrenal tumors (BATs) – mainly adreno- cortical adenomas – from non-adenomas. This group mainly consists of adrenocortical carcinomas (ACCs) and adrenal metastases from other malignancies, and some- times pheochromocytomas. A pooled analysis of multiple published studies by Boland et al. (1) suggested an attenuation threshold of 10 hounsfield units (HU) for regular unenhanced CT to detect malignant lesions with a sensitivity of 98% and a specificity of 71%. However, all of the larger studies on this topic primarily focused on European Journal of Endocrinology Clinical Study S Petersenn, P-A Richter and others Adrenocortical carcinoma in unenhanced CT 172 :4 415–422 www.eje-online.org Ñ 2015 European Society of Endocrinology DOI: 10.1530/EJE-14-0916 Printed in Great Britain Published by Bioscientifica Ltd. Downloaded from Bioscientifica.com at 05/24/2020 03:22:00AM via free access