Extrasellar, intracavernous sinus adrenocorticotropin-releasing adenoma causing Cushing's disease.

This report describes a patient with pituitary-dependent Cushing's disease who had a preoperative ACTH gradient to the left at the level of the cavernous sinus. Intraoperatively, an adenoma was found entirely within the left cavernous sinus, with no direct connection to the pituitary gland. To our knowledge, such a tumor has not been reported previously. This case has implications for the diagnosis, treatment, and follow-up of patients with pituitary-dependent Cushing's disease. The presence of an entirely extrasellar ACTH-releasing adenoma in the cavernous sinus could explain why pituitary-dependent Cushing's disease may persist postoperatively, even after total hypophysectomy. The diagnosis of an intracavernous tumor can be established by cavernous sinus venography. An extrasellar intracavernous adenoma can be diagnosed intraoperatively after careful negative exploration of the sellar contents followed by incision of the cavernous sinus on the side of the ACTH gradient established by venous sampling.