The Ectopic Adrenocorticotropin Syndrome: Clinical Features, Diagnosis, Management, and Long-Term Follow-Up

There are few large series of patients with ectopic, nonpituitary, corticotropin (ACTH) secretion (EAS).The objective of this study was to analyze the clinical, biochemical, and radiological features, management, and treatment outcome of patients with EAS.This was a retrospective case-record study.The setting for this study was a tertiary referral hospital center.Forty patients with EAS were studied.Clinical, biochemical, and radiological features and response to therapy and survival were measured.The median follow-up was 5 yr (range, 2-30 yr). None of the dynamic tests achieved 100% accuracy, but bilateral inferior petrosal sinus sampling showed an absent central gradient in all but one case (one of 12). Imaging correctly identified the lesion at first investigation in 65% of cases. Bronchial carcinoid tumors were the most common cause of EAS (n = 12; 30%), followed by other neuroendocrine tumors (n = 13, 32.5%). In 12.5% of patients, the source of EAS was never found. Octreotide scintigraphy and whole-body venous sampling were of limited value. Surgical attempt at curative resection was successful in 83% (10 of 12) of patients with bronchial carcinoid tumors; others responded generally well to adrenolytic therapy or bilateral adrenalectomy. Tumor histology and the presence of distant metastases were the main predictors of overall survival (P < 0.05).A variety of tests and imaging studies are necessary for the correct diagnosis of the EAS, but even then, up to 20% of cases present a covert or occult EAS syndrome. These cases require a prolonged follow-up, review, and repetition of diagnostic tests and scans.