Adrenal Incidentaloma and Subclinical Cushing's Syndrome: A Longitudinal Follow-Up Study by Endoscopic Ultrasound

Purpose Adrenal incidentaloma (AI) and adrenal masses in cases of subclinical Cushing's syndrome (SCS) initially require follow-up imaging. In this study we used endoscopic ultrasound (EUS) as a method for high-resolution imaging. The aim was to evaluate the growth rate of AI and SCS by EUS. Materials and Methods This retrospective analysis included 93 out of 229 patients with AI or SCS who were investigated longitudinally by EUS in our university hospital between 1997 and 2013. The longitudinal follow-up required at least two investigations by EUS and evaluation of endocrine function. Plasma renin, serum aldosterone, 24 h urinary catecholamines and 2mg dexamethasone suppression test were performed.EUS was performed at baseline and during follow-up. Each time, the maximum diameter was measured. Three groups were defined: non-functioning adenomas (NFA), non-functioning nodular hyperplasias (NFH) and SCS. Results 86 patients had non-functioning masses [NFM] (59 NFA, 48 NFH) and 7 patients had SCS (10 masses). At baseline the mean diameter was 19.4 (+/- 9.3) mm (NFM) and 19.6 (+/- 9.2) mm (SCS). The mean follow-up period was 31.6 +/- 28.7 months. The estimated mean growth rates per year were low: They were 0.35 mm/yr [NFA], 0.02 mm/yr [NFH] and 0.53 mm/yr [SCS]. Furthermore, there was no malignant progression of any mass. Conclusion The growth rate as determined by EUS was low for all tumor entities observed in this study. There was no difference in tumor growth between the groups.