Experience of Ectopic ACTH Syndrome: 88 cases with identified causes.

Abstract Objective Ectopic adrenocorticotropic hormone syndrome (EAS) is a rare cause of Cushing’s syndrome, and diagnosis and management remain challenging. The aim of this study was to present the clinical spectrum of a group of EAS cases in a single center to explore better management strategies. Methods A retrospective study was conducted to identify 88 confirmed EAS cases at our hospital from 1984 to 2019. The clinical, biochemical, imaging and pathological features were analyzed. Results Of the 88 eligible EAS patients, 38 (43.2%) cases of pulmonary neuroendocrine tumors (NETs) and a larger number of thymic/mediastinal NETs (29 cases, 33%) were identified. The clinical and biological features of EAS and Cushing’s disease (CD) overlapped but were more severe in EAS. Inferior petrosal sinus sampling (IPSS, 97.4%) and computed tomography (CT, 85.4%) provided the highest positive diagnostic accuracy. CT is also a useful tool to identify tumors in chest cavity compared with non-chest lesions (91.2% vs 57.1%). Although a greater tumor size (4.54 cm vs 1.44 cm) and higher rate of unsuppressible high-dose dexamethasone suppression test (83.3% vs 51.5%) were found in thymic/mediastinum NETs than in pulmonary NETs, the level of hormone production had no difference. Conclusions EAS had more common and severe clinical presentations than CD, and multiple imaging approaches are required for reliable diagnosis. A higher rate of thymic/mediastinal NETs were found in our study. For patients without a certain tumor source, long-term follow-up and further evaluations are needed.