Síndrome de Cushing: una revisión a propósito de una casuística nacional / Cushing's syndrome: a review apropos of a national series

RESUMO

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 responseible for the syndromatic diagnosis, easily done by using 2 simple tools the measurement of basal free urinary cortisol and the performance of and 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 transphenoidal approach to the pituitary gland as well surgeons well experience in adrenal surgery sre a must to offer a reasonable chance of success to patients with the syndrome. Forty one (82 percent) of the series were female patients, 78 percent were pituitary-depent and 22 percent pituitary-independent Cushings. Six out of 8 (75 percent) of the adrenal tumors were carcinomas. Only 3 patients (6 percent) qualified as ectopic ACTH syndormes. 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 od the offending tumor (1 of 3 cases) or bilateral adrenalectomy (2 of 3 cases) Pituitary-dependent Cushing are quite tricky to diagnose and difficult to treat. Transphenoidal resection of the offending microadenoma was successful in only 43.5 percent (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 39 patients with Cushing's disease (18 percent) ultimately died for a variety of reasons; six out of 6 patients (100 percent) with adrenal carcinoma died of dissemination; 2 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