Ectopic ACTH-secreting syndrome: a single center experience report with a high prevalence of occult tumor.
BACKGROUND
Differentiation between the two forms of ACTH-dependent Cushing's syndrome is a challenging task. Although the majority of these cases will be diagnosed as Cushing's disease secondary to an ACTH-secreting pituitary adenoma, 10-15% result from the ectopic ACTH secretion syndrome (EAS), which is usually due to neuroendocrine tumors. In the present study we report our experience with EAS in eight patients evaluated and treated during the past 10 years.


METHODS
Our experience in the evaluation and management of EAS was retrospectively reviewed. The latter included a standard biochemical assessment (urinary free cortisol, low- and high-dose dexamethasone suppression tests), petrosal sinus sampling when indicated and imaging techniques such as pituitary MRI, total body CT and somatostatin receptor scintigraphy.


RESULTS
The ectopic nature of the ACTH hypersecretion was confirmed with inferior petrosal sinus samplings in all cases. CT scanning localized a putative tumor in 6/8 patients, whereas octreotide scintigraphy was positive in only five. In all cases, the source was traced to the lungs. However, upon performing thoracotomy, a documented ACTH-secreting bronchial carcinoid tumor was found in only four patients. Thus, 4/8 patients with EAS remained "occult." All of these patients underwent adrenalectomy for hypercortisolism control.


CONCLUSIONS
EAS is a rare cause of ACTH-dependent Cushing's syndrome. Truly "occult" tumors were frequent and these patients need to be under close surveillance for the detection of neuroendocrine tumors.
Hernández
Irma
I
Endocrinology Service, Hospital de Especialidades, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico.
Espinosa-de-los-Monteros
Ana Laura
AL
Mendoza
Victoria
V
Cheng
Sonia
S
Molina
Mario
M
Sosa
Ernesto
E
Mercado
Moisés
M
D000182:ACTH Syndrome, Ectopic / Q000175:diagnosis* / Q000601:surgery; D049913:ACTH-Secreting Pituitary Adenoma / Q000175:diagnosis* / Q000601:surgery; D000236:Adenoma / Q000175:diagnosis* / Q000628:therapy*; D000315:Adrenalectomy; D003480:Cushing Syndrome / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome