Abstract
Ectopic ACTH-syndrome is a rare cause of Cushing’s disease. Despite extensive diagnostic
procedures the source of ACTH secretion often remains occult.
This case describes a 45-year old woman with an ectopic Cushing’s syndrome. Extensive
imaging procedures including CT scan of chest and abdomen, octreotide scan and MRI
of the chest and pituitary did not reveal the source of ACTH secretion.
In consideration of an occult source of ACTH secretion we started a therapeutic trial
with cabergoline (0.5 mg/d), a dopamine receptor agonist, which has been shown to
be effective in ectopic Cushing’s syndrome. 2 months after cabergoline treatment had
been initiated, ACTH and cortisol levels normalized in association with significant
improvement of the clinical symptoms.
During follow-up a [68Ga-DOTA-dPhe1, Tyr3]-octreotate ([68Ga-DOTA]-TATE) PET-CT was performed revealing a somatostatin receptor positive lesion
in the right sphenoidal sinus suggesting the source of ACTH secretion. The patient
was cured by transnasal resection of the polypoid lesion, which was immunohistochemically
characterized as an ACTH-positive neuroendocrine tumor.
This case report demonstrates the management of ectopic ACTH-syndrome by molecularly
targeted therapy with dopamine receptor agonists as well as improved detection of
the ectopic ACTH source by novel imaging modalities, such as [68Ga-DOTA]-TATE PET specifically targeting somatostatin receptor subtype-2 with high
affinity.
Key words
pituitary adenoma - glucocorticoids - cabergoline - DOTA-TATE-PET
