Somatostatin receptor scintigraphy and the ectopic ACTH syndrome--the solution or just another test?

Ectopic Cushing's syndrome and pulmonary carcinoid tumour identified by [111In-DTPA-D-Phe1]octreotide

The differential diagnosis and management of Cushing's syndrome remain difficult, particularly for ectopic adrenocorticotropin (ACTH) syndromes resulting from small bronchial carcinoids. We report the case of a 41-year-old man with ectopic ACTH-dependent Cushing's syndrome. Two computed tomography scans of the thorax were normal and magnetic resonance imaging of the chest showed a 6-mm hyperintense T1-weighted area close to the left pulmonary hilus, interpreted as probably vascular by the radiologists. An [111In-DTPA-D-Phe1]octreotide scintigraphy scan demonstrated a positive image for somatostatin receptors in exactly the same location and surgery confirmed the presence of a small ACTH-secreting carcinoid tumour in the upper left lung lobe which was resected. Surgery cured the hypercorticism of the patient. The differential diagnosis of Cushing's syndrome and the procedure for localisation of an ACTH source are discussed.

Successful localization of an occult ACTH-secreting bronchial carcinoid tumour with 111indium-DTPA labelled octreotide

Ectopic ACTH secretion due to occult carcinoid tumours is an occasional cause of ACTH dependent Cushing's syndrome. In many cases the ectopic source may be obvious, but sometimes no obvious source is evident, the so-called occult ectopic syndrome. Due to their small size, localization of such occult tumours, particularly bronchial carcinoids, may be extremely difficult. Whole body CT and venous sampling studies have been used but are not always successful in determining the site of such lesions. We report a 40-year-old patient with the ectopic ACTH syndrome due to a 0.6-cm bronchial carcinoid tumour which was successfully localized by 111indium-DTPA labelled octreotide scintigraphy.