Recurrent ectopic adrenocorticotropic hormone producing thymic carcinoid detected with octreotide imaging.

Primary thymic carcinoids are rare tumors in which the tumor cells retain functional somatostatin receptors. In-111-labeled octreotide imaging has been used to diagnose abdominal carcinoids with a sensitivity rate of approximately 87%. The authors describe a case of a recurrent, ectopic cortisol-releasing hormone that produced thymic carcinoid localized as a focal area of increased activity in the upper mediastinum when planar and tomographic octreotide scintigraphy was used. Chest CT and MRI failed to localize the tumor. This may be the first reported case of In-111-labeled octreotide used to identify Cushing's syndrome caused by a cortisol-releasing hormone that produced thymic carcinoid.