Failure of hypophysectomy to correct pituitary-dependent Cushing's disease in two patients.

One woman (patient 1), aged 27 years, and one man (patient 2), aged 26 years, had pituitary surgery for pituitary-dependent Cushing's syndrome. An adenoma was identified and removed in both patients. Persistence of hypercortisolism characterized the response of patient 2 to surgery; transient hypoadrenalism, the response of patient 1. Patient 1 subsequently underwent a relapse. At the second surgery (total hypophysectomy for both patients), hyperplasia was demonstrated in patient 1, and scattered nests of adrenocorticotropic hormone (ACTH)-secreting cells were demonstrated in patient 2. Postoperatively, Cushing's syndrome persisted in both patients. Inferior petrosal sampling for ACTH during corticotropin releasing hormone stimulation verified a pituitary source of ACTH in patient 1. A decrease in cortisol secretion following hypophysectomy and subsequent cure by pituitary irradiation constitutes the evidence for pituitary origin in patient 2. Dexamethasone suppression and corticotropin releasing hormone-stimulation tests consistently suggested a pituitary cause throughout the clinical course of both patients. Computed tomographic scans after hypophysectomy revealed postoperative changes only. In both patients, panhypopituitarism, except for cortisol and ACTH, followed hypophysectomy. It may be concluded that patients with diffuse pituitary ACTH hyperplasia cannot, at present, be identified preoperatively by conventional clinical testing. Surgery for such patients may not be the therapy of choice.