Ectopic Adrenocorticotropic Hormone-Secreting Bronchial Carcinoid Diagnosed by Balloon-Occluded Pulmonary Arterial Sampling

We present the case of a 50-year-old man with Cushing syndrome caused by an ectopic adrenocorticotropic hormone (ACTH)-secreting tumor. A small nodule was located in close association with the lateral segmental branch of the pulmonary artery in the left upper lobe. Blood samples were obtained from various branches of the pulmonary artery by balloon-occluded retrograde sampling for the measurement of location-specific serum ACTH levels. After confirmation that the pulmonary nodule was responsible for the increased ACTH secretion, lobectomy was performed. This report demonstrates the usefulness of balloon-occluded retrograde pulmonary arterial sampling for the preoperative diagnosis of an ACTH-producing tumor whose diagnosis is difficult to confirm.