Negative surgical exploration in patients with Cushing's disease: benefit of two-thirds gland resection on remission rate and a review of the literature

OBJECTIVE The authors report their single-institution experience with the pathological findings, rates of remission, and complications in patients with presumed Cushing's disease (CD) who underwent a two-thirds pituitary gland resection when no adenoma was identified at the time of transsphenoidal surgery (TSS). The authors also review the literature on patients with CD, negative surgical exploration, and histological findings. METHODS This study is a retrospective analysis of cases found in neurosurgery and pathology department databases between 1989 and 2011. In all cases, patients had been operated on by the same neurosurgeon (K.O.L.). Twenty-two (13.6%) of 161 patients who underwent TSS for CD had no adenoma identified intraoperatively after systematic exploration of the entire gland; these patients all underwent a two-thirds pituitary gland resection. A chart review was performed to assess treatment data points as well as clinical and biochemical remission status. RESULTS Of the 22 patients who underwent two-thirds gland resection, 6 (27.3%) ultimately had lesions found on final pathology. All 6 patients were found to have a distinct adrenocorticotropic hormone (ACTH) cell adenoma. Sixteen (72.7%) of the patients had no tumor identified, with 3 of these patients suspected of having ACTH cell hyperplasia. The follow-up duration for the entire group was between 14 and 315 months (mean 98.9 months, median 77 months). Remission rates were 100% (6/6 patients) for the ACTH cell adenoma group and 75% (12/16) for the group without adenoma. Overall, 18 (81.8%) of the 22 patients had no evidence of hypercortisolism at last follow-up, and 4 patients (18%) had persistent hypercortisolism, defined as a postoperative cortisol level > 5 mu g/dl. Of these 4 patients, 1 was suspected of harboring a cavernous sinus adenoma, 2 were found to have lung tumors secreting ACTH, and 1 remained with an undiagnosed etiology. Rates of postoperative complications were low. CONCLUSIONS The diagnosis and treatment of CD can be challenging for neurosurgeons, endocrinologists, and pathologists alike. Failure to find a discrete adenoma at the time of surgery occurs in at least 10%-15% of cases, even in experienced centers. The current literature provides little guidance regarding rational intraoperative approaches in such cases. The authors' experience with 161 patients with CD, when no intraoperative tumor was localized, demonstrates the utility of a two-thirds pituitary gland resection with a novel and effective surgical strategy, as suggested by a high initial remission rate and a low operative morbidity.