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

Abstract

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.

Usefulness of Somatostatin Receptor Scintigraphy in Patients with Occult Ectopic Adrenocorticotropin Syndrome

“…Whereas normal scintigrams are observed in patients with ACTH-secreting pituitary tumors (9,11), SRS has demonstrated its ability to localize ACTH-secreting carcinoid tumors, most of these being located within the bronchial tree (Table 1). However, careful analysis of the 20 cases of ACTH-secreting carcinoids reported with sufficient details in English medical literature reveals that: 1) 12 were also evident using CT or MRI scanning (11, 12, 16, 18, 21-25); 2) 3 were not visualized initially because of the use of standard-cut CT, and these tumors were visualized when high-resolution CT of the chest was performed thereafter (17,19,20); and 3) SRS was useful only in confirming a suspected lesion seen with conventional imaging in 3 cases (13,15,26). Finally, SRS was of undeniable help and more sensitive than conventional imaging in only 2 (10%) cases (14,24).…”

“…ϩ ϩ De Herder (11) Pancreatic carcinoid (?) ϩ ϩ Iser (12) Bronchial carcinoid (20) ϩ ϩ Phlipponneau (13) Bronchial carcinoid (7) Ϯ ϩ Weiss (14) Bronchial carcinoid (10) Ϫ ϩ Lefebvre (15) Bronchial carcinoid (9) Ϯ ϩ Olario (16) Bronchial carcinoid (20) ϩ ϩ Tsagarakis (17) Bronchial carcinoid (6) ϩ ϩ Christin-Maitre (18) Bronchial carcinoid (10) ϩ ϩ Kristofferson (19) Bronchial carcinoid (20) ϩ ϩ Briganti (20) Bronchial carcinoid (20) ϩ ϩ Carreta (21) Bronchial carcinoid (10) ϩ ϩ Fernandez (22) Bronchial carcinoid (20) ϩ ϩ Mansi (23) Bronchial carcinoid (18) ϩ ϩ Segu (24) Midgut carcinoid (?) Ϫ ϩ Schrager (25) Bronchial carcinoid (?)…”

Octapeptide somatostatin-analogue therapy of Cushing's syndrome

“…Tumours and metastases, which bear receptors for octapeptide analogues, can be visualised in vivo using gamma camera pictures obtained after injection of 111 In-pentetreotide (OctreoScan, Mallinckrodt, Petten, The Netherlands) 1 Table  Pentetreotide scintigraphy for the detection of occult ectopic ACTH-secreting tumours Reference Primary tumour Scan Tumour diameter (mm) Metastases Present Visualised 16 bronchial carcinoid + 10×15 + + 16 bronchial carcinoid + 12×18 − − 17 bronchial carcinoid + 10 + − 18 bronchial carcinoid + 6 − − 19 bronchial carcinoid + 9 − − 20 bronchial carcinoid + 6 − − 21 bronchial carcinoid + 20 − − 22 bronchial carcinoid +...…”

Use of In-111 pentetreotide scintigraphy in the diagnosis of a midgut carcinoid causing Cushing's syndrome

“…Reviewing published reports so far, eight of ten (including the present case) 'occult' tumors which were not visualized by standard radiographic imaging could be localized by this technique (23)(24)(25)(26)(27)(28)(29)(30)(31). Of the eight visualized tumors, five were bronchial carcinoids (26,(28)(29)(30)(31), one was an epigastric neuroendocrine tumor (27), one was a pancreatic islet cell tumor (24), and one was an ileal carcinoid (present case). From the published data, the size of the primary tumor first localized by pentetreotide scanning ranged from 6 to 25 mm, the largest one being a pancreatic islet cell neoplasm (24), which was not localized by initial CT or MRI but later confirmed by endoscopic ultrasound after localization with the pentetreotide scan.…”