Cushing Syndrome Caused by Ectopic Adrenocorticotropic Hormone–Secreting Pituitary Adenomas: Case Report and Literature Review

Abstract

Ectopic adrenocorticotropic hormone-secreting pituitary adenomas (EAPAs) are rare adenomas causing Cushing syndrome, which are located in ectopic locations outside the sella turcica. No more than 100 cases of this entity have been reported. Because of its rarity and nonspecific clinical and biochemical features, EAPA is often misdiagnosed, leading to surgical failure and delayed treatment. In the article, the cases of 3 patients with suprasellar EAPAs treated at our institution are reported and a review of the literature is presented. All 3 patients with Cushing syndrome had ectopic pituitary adenomas located in the suprasellar region and identifiable on preoperative sellar magnetic resonance imaging. Preoperative laboratory evaluation in all patients showed identical results to those observed in Cushing disease. In 2 patients, craniotomies were performed directly to achieve total tumor resection and clinical remission. One patient, who underwent previous negative transsphenoidal exploration, achieved full remission through a second craniotomy despite pulmonary infection as a postoperative complication. Although EAPA is an extremely rare entity, it should be considered as a differential diagnosis of Cushing disease. Because of its similar clinical and biochemical behavior to intrasellar pituitary adrenocorticotropic hormone adenoma in Cushing disease, careful examination of the potential occurrence of EAPA on preoperative radiologic imaging is of considerable significance to avoid unnecessary surgery and achieve improved outcomes. Surgical resection EAPA remains the first choice of treatment, and the optimal surgical approach ought to be determined according to the adenoma features, the general condition of the patient, and the surgeon's experience.