The relationship between efficacy of surgical treatment of Cushing disease and pathological -- immunohistochemical and ultrastructural -- confirmation of corticotroph tumour presence.

BACKGROUND AND PURPOSE The most common cause of Cushing disease (CD) is ACTH-secreting pituitary adenoma. Transsphenoidal selective adenomectomy is the treatment of choice. Frequency of remission varies from 60% to 90%, depending on the site and the surgeon's experience. This study aims to answer the question whether confirmation of corticotroph adenoma in pathological examinations increases the probability of surgical cure for CD. MATERIAL AND METHODS The prospective study involved 36 patients with CD operated on with the transsphenoidal approach and followed up for at least 18 months. Following the surgical procedure, the specimen was examined by a pathologist. The study evaluated the significance of positive histological (immunohistochemical and ultrastructural) examination results for achieving surgical cure for CD. RESULTS Twenty-three of 36 patients (63.9%) were regarded as being surgically cured of CD. Persistent CD was confirmed in 13 patients (36.1%). Pituitary insufficiency was found in 5 patients (13.9%), whereas 3 patients (8.3%) were diagnosed with diabetes insipidus. A significant difference was demonstrated between the cured and the non-cured group with reference to the results of pathological examination of surgical specimens. Pathomorphological confirmation of corticotroph adenoma was significantly more frequently observed in the cured group in comparison with the non-cured group (p = 0.028). CONCLUSIONS Pathological confirmation of corticotroph pituitary adenoma may be regarded as an important predictor of the surgical cure of CD.