Ectopic Adrenocorticotropic Hormone Syndrome:An Update & Case Presentation

سال انتشار: 1398
نوع سند: مقاله کنفرانسی
زبان: انگلیسی
مشاهده: 417

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شناسه ملی سند علمی:

ICEMU05_010

تاریخ نمایه سازی: 9 آذر 1398

چکیده مقاله:

The ectopic adrenocorticotropic hormone (ACTH) syndrome (EAS) is rare and comprises around 10% to 20% of ACTH-dependent Cushing’s syndrome and 5% to 10% of all types of Cushing’s syndrome. A broad spectrum of malignancies are associated with the EAS, including small cell lung cancer(SCLC) and other neuroendocrine tumors (NETs), predominantly pulmonary, thymic, and pancreatic carcinoids, and more rarely, medullary thyroid carcinoma and pheochromocytoma. There are epidemiological and clinical features that can help discriminate between the EAS and Cushing’s disease. The age of onset and the gender ratio differs, with EAS occurring in older age and only slightly more often in women compared with Cushing’s disease. There is significant heterogeneity in clinical features of EAS related to the malignant potential of the underlying tumor and the severity of the hypercortisolism. Regarding the ACTH levels, although patients with the EAS, especially secondary to SCLC, tend to have higher ACTH and cortisol levels, there remains significant overlap between the EAS and Cushing’s disease cohorts. Discriminating between the EAS and Cushing’s disease is challenging because bothpulmonary carcinoids and pituitary corticotroph tumors are often small and difficult to detect, even with sophisticated imaging. On the other hand, lack of a demonstrable tumor on MRI has been reported in up to 40% of patients with proven Cushing’s disease. Hence, there is a reliance on biochemical testing to direct the imaging to the appropriate site, although even this may be challenging because small ectopic sources may still contain many of the intrinsic regulatory mechanisms of corticotroph tumors. Biochemical dynamic tests have variable sensitivity and specificity and have more discriminatory power when interpreted in combination. Neither the HDDST nor the CRH stimulation tests alone consistently discriminate between Cushing’s disease and the EAS, although responses to either clearly shift the probability in favor of Cushing’s disease. The desmopressin test has even less utility than CRH in the differential diagnosis of ACTHdependent Cushing’s syndrome, even when combined with CRH. Furthermore, when using optimal criteria, the combination of the LDDST and CRH test had similar diagnostic accuracy (sensitivity 94%, specificity 97%) compared with the combination of the HDDST and CRH test, and it can be argued that the HDDST provides little additional information. Notably, Up to 25% of EAS patients may have discordant dynamic test results.

نویسندگان

Fatemeh Esfahanian,

M.D.Associate Professor of Endocrinology & Metabolism Department of Internal Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran