Ectopic Adrenocorticotropic Hormone–Secreting Pituitary Adenoma Localized by 18F-Choline PET/CT

Abstract The criterion standard of treatment of an adrenocorticotropic hormone (ACTH)–secreting pituitary adenoma is complete surgical excision. However, ectopic location of these adenomas is an extremely rare condition, which may affect the diagnosis and treatment success. We report a case of a 49-year-old man who was referred to our institution with persistent hypercortisolemia after an unsuccessful attempt of surgical resection. 18 F-choline PET/CT revealed increased radiopharmaceutical uptake in a nodule localized in the left maxillary sinus, which was proved at histology to be an ectopic ACTH-secreting pituitary adenoma staining positive for ACTH. Imaging with 18 F-FDG PET/CT and 68 Ga-DOTA-NOC PET/CT was not diagnostic.