Comment on Primary Localization of an Ectopic ACTH-Producing Bronchial Carcinoid Tumor by Indium111 Pentetreotide Scintigraphy

Martin Reincke

University Hospital of Freiburg Freiburg, Germany

Bruno Allolio, Wiebke Arlt and Carsten Körber

University Hospital of Würzburg, Würzburg, D-98080 Germany

Torpy et al. (1) and Tabarin et al. (2) reported recently a low diagnostic sensitivity of Indium111 pentetreotide scintigraphy as a tool for the localization of ectopic ACTH-producing tumors. de Herder and Lamberts in their editorial comment (3) suggested that, despite these negative results, Indium111 pentetreotide scintigraphy could be helpful in a minority of patients with Cushing’s disease and should be used in the localization procedure of ectopic ACTH sources. We would like to emphasize this view with a short case report of a recent patient in whom Indium111 pentetreotide scintigraphy remained the only procedure to localize an extremely small ACTH-producing bronchial carcinoid.

A 37-yr-old male patient was admitted with hypokalemic hypertension, muscle weakness, hyperglycemia, weight gain, facial swelling, and psychosis. The diagnosis of ACTH-dependent Cushing’s syndrome was established. Plasma ACTH and cortisol concentrations were unresponsive to corticotropin releasing CRH hormone and high dose dexamethasone, suggesting ectopic Cushing’s syndrome. The diagnosis was confirmed by inferior sinus petrosal catherterization, which demonstrated no gradient between the pituitary and the peripheral ACTH levels. Computed tomography (CT) and magnetic resonance imaging (MRI) of chest and abdomen did not visualize the ectopic ACTH source. Adrenostatic treatment was introduced but failed to control hypercortisolism. The patient underwent bilateral adrenalectomy. The postoperative period was uneventful, and the patient recovered from Cushing’s syndrome. At follow-up, plasma ACTH concentrations were steadily increasing, suggesting tumor progression, but CT and MRI scans of the chest and the abdomen after 3, 6, and 9 months did not identify the ectopic ACTH source. Indium111 pentetreotide scintigraphy scanning with 214 Mbq Indium111 octreotide was performed, revealing a spot in the left lung 24-h post-injection (Figs. 1Go and 2Go). In spite of this finding, CT (2 mm slices) and MRI were still unable to localize the tumor. Exploratory thoracotomy was performed, and an atypical bronchial carcinoid tumor measuring 0.6 mm in segment 6 of the lower lobe was resected. This case illustrates that Indium111 pentetreotide scintigraphy can be of extreme value in a small minority of patients with the ectopic Cushing’s syndrome.



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Figure 1. Whole body scan from dorsal with solitary, high intensity spot in the left lung and physiological uptake in liver, spleen, and the urinary tract.

 


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Figure 2. Magnification of Fig. 1Go showing the lesion from ventral (left) and dorsal (right).

 

Footnotes

Address correspondence to: Martin Reineke, M.D., Schwerpunkt Endokrinologie, Abteilung Innere Medizin II, Klinikum der Albert-Ludwigs-Universität Freiburg, Hugstetter Strasse 55, Freiburg, Germany D-79106.

Received May 20, 1999.

References

  1. Torpy DJ, Chen CC, Mullen N, et al. 1999 Lack of utility of 111 In-pentetreotide scintigraphy in localizing ectopic ACTH producing tumors: follow-up of 18 patients. J Clin Endocrinol Metab. 84:1186–1192.[Abstract/Free Full Text]
  2. Tabarin A, Valli N, Chanson P, et al. 1999 Usefulness of somatostatin receptor scintigraphy in patients with occult ectopic adrenocorticotropin syndrome. J Clin Endocrinol Metab. 84:1193–1202.[Abstract/Free Full Text]
  3. de Herder WW, Lamberts SW. 1999 Editorial: Tumor localization—the ectopic ACTH syndrome. J Clin Endocrinol Metab. 84:1184–1185.[Free Full Text]