[Cushing's syndrome: review of a national caseload]

Cushing's syndrome occurs rarely; in analyzing 50 cases studied at our institution we discuss the following aspects: syndromatic diagnosis, etiologic differentiation into the 3 categories of the syndrome, and therapeutic strategies for each variety. We postulate that non-endocrinologists should be responsible for the syndromatic diagnosis, easily done by using 2 simple tools: the measurement of basal free urinary cortisol and the performance of an overnight suppression of the adrenal axis with 1 mg of dexamethasone (Nugent's test). In contrast, the etiologic diagnosis and the therapeutic interventions should be strictly restricted to highly specialized institutions having well seasoned endocrinologists, a reliable endocrine laboratory, easy access to computed tomographies of the brain and abdomen as well as to nuclear resonance imaging of the brain. The usefulness of our in-house devised vasopressin challenge following overnight dexamethasone suppression for the etiologic diagnosis is highlighted. Neurosurgical expertise in the transsphenoidal approach to the pituitary gland as well surgeons well experienced in adrenal surgery are a must to offer a reasonable chance of success to patients with the syndrome. Forty one (82%) of the series were female patients, 78% were pituitary-dependent and 22% pituitary-independent Cushings. Six out of 8 (75%) of the adrenal tumors were carcinomas. Only 3 patients (6%) qualified as ectopic ACTH syndromes. The easiest variety to diagnose and treat was the adrenal adenoma (2 cases); adrenal carcinomas were always incurable. The ectopic ACTH syndrome was amenable to successful medical treatment with ketoconazole or surgical resolution with complete resection of the offending tumor (1 of 3 cases) or bilateral adrenalectomy (2 of 3 cases) Pituitary-dependent Cushings are quite tricky to diagnose and difficult to treat. Transsphenoidal resection of the offending microadenoma was successful in only 43.5% (10/23) of cases and we experienced 3 recurrences of the syndrome even after 8 years of successful removal of the pituitary adenoma. The remainder had to be cured by bilateral adrenalectomy. Seven out of 39 patients with Cushing's disease (18%) ultimately died for a variety of reasons; six out of 6 patients (100%) with adrenal carcinoma died of dissemination; two out of 2 adrenal adenomas cured and 1 out of the 3 ectopic ACTH syndromes died of dissemination of a malignant thymic carcinoma. We conclude that Cushing's syndrome is a serious, underdiagnosed disorder, which should be suspected and diagnosed by the non specialized physician and then referred to a specialized center for expert etiologic diagnosis and surgical therapy.