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

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. 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 F-FDG PET/CT and Ga-DOTA-NOC PET/CT was not diagnostic.