Cushing Syndrome due to Ectopic Adrenocorticotropic Hormone Secretion by a Pulmonary Carcinoid Tumor in a Patient with Pneumoconiosis

ABSTRACT Objective: Sites with a high prevalence of pneumoconiosis are especially challenging to physicians. The presence of pneumoconiotic nodules on chest computed tomography (CT) scans makes it difficult to localize the source of ectopic adrenocorticotropic hormone (ACTH). Because of false-positive results that may occur with the use of fluorine 18-fluorodeoxyglucose positron emission tomography CT (PET/CT) scans, alternative imaging modalities are needed. Methods: Gallium 68-dodecanetetraacetic acid tyrosine-3-octreotate (68Ga-DOTATATE) is a positron emitter-labeled somatostatin analog used with PET/CT. 68Ga-DOTATATE may improve the diagnostic accuracy of localizing ectopic ACTH-secreting carcinoid tumors in patients with pneumoconiosis by reducing false-positive results. Results: We describe a patient with pneumoconiosis and Cushing syndrome due to ectopic ACTH from a pulmonary carcinoid tumor, highlighting challenges in diagnosis and management. Conclusion: Prospective studies comparing fluorine 18-fluorodeoxyglucose PET/CT with 68Ga-DOTATATE PET/CT for diagnosis of bronchial carcinoid tumors in patients with ectopic ACTH and pneumoconiosis are highly needed. We also review the scarce available literature and provide recommendations based on our experience. Abbreviations: 18F-FDG = fluorine 18-fluorodeoxyglucose; 68Ga-DOTATATE = gallium 68-dodecanetetraacetic acid tyrosine-3-octreotate; CTH = adrenocorticotropic hormone; CT = computed tomography; MRI = magnetic resonance imaging; NET = neuroendocrine tumor; PET = positron emission tomography; SSTR = somatostatin receptor; SUV = standardized uptake value; SUVmax = maximum tandardized uptake value