Ectopic ACTH-secreting syndrome: a single-center experience.

OBJECTIVE

Ectopic adrenocorticotropic hormone (ACTH)-secreting syndrome (EAS) is a rare cause of ACTH-dependent endogenous hypercortisolism. The objective of this study was to analyze clinical, biochemical, and imaging characteristics; management strategies; and outcomes of EAS patients.

METHOD: We screened the records (1993-2012) of ACTH-dependent endogenous hypercortisolism cases managed at a tertiary care center.

RESULTS

Of the 218 patients, 17 were diagnosed with EAS. The median 8:00 AM serum cortisol was 36 μg/dL (11.4-82.7 μg/dL), and the median basal plasma ACTH was 156 pg/mL (53.5-468 pg/mL). Notably, ACTH levels below 100 pg/mL were found in 4 patients. Suspicious microadenoma was found on magnetic resonance imaging (MRI) of the pituitary in 5 patients, and all of them underwent transsphenoidal surgery (TSS). Inferior petrosal sinus sampling (IPSS) was performed in 8 patients, and the results were suggestive of a peripheral source in all 8. Computed tomography (CT) localized the lesion in 15/17 patients. In 2 patients with negative CTs, gallium DOTATATE positron emission tomography (PET) scans localized the lesion. Despite difficulties localizing bronchial carcinoids, the cure rate was high (72%). In contrast, thymic carcinoids were easily localized but had poor outcomes.

CONCLUSION

EAS cannot be ruled out on the basis of marginally elevated ACTH. In cases with an equivocal MRI pituitary finding, prior IPSS can help avoid unnecessary TSS. CT is a useful modality for localization of an ectopic source. Functional imaging may help in cases where anatomical imaging fails.