(dtpa-phe(1))-octreotide and Cushing-Syndrome

Topics: ACTH Syndrome, Ectopic; Adult; Bronchial Neoplasms; Carcinoid Tumor; Cushing Syndrome; Diagnosis, Differential; Humans; Indium Radioisotopes; Male; Octreotide; Pentetic Acid; Radiopharmaceuticals; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Bronchial carcinoid (BC) is a rare etiology of Cushing syndrome, and difficulties in differential diagnosis with Cushing's disease are often present. We report two cases in which octreotide scintigraphy was an important diagnostic tool. The first patient showed a 1 cm non-specific pulmonary nodule on CT scan that was positive on scintigraphy, being confirmed by surgery. The second case was a man that had been operated but not cured of an ACTH secreting BC that continued with high ACTH levels and negative localization imaging studies. A subsequent scintigraphy showed a positive image suggestive of recurrence. Octreotide scintigraphy may be considered in patients with suspicion of ectopic ACTH syndrome although a positive image in CT scan be present.

Topics: Aged; Bronchial Neoplasms; Carcinoid Tumor; Cushing Syndrome; Female; Humans; Male; Middle Aged; Octreotide; Pentetic Acid; Radionuclide Imaging; Radiopharmaceuticals

Bronchial carcinoid tumors are neuroendocrine neoplasms capable of expressing somatostatin receptors and of secreting neuromediators such as ACTH and chromogranins. Radiologic appearance is usually non-specific and has to be distinguished from benign pulmonary nodules and other malignant diseases. Standard radiological techniques have limited accuracy in the evaluation of such lesions. Radioisotopic imaging techniques may increase the specificity of diagnostic assessment. The role of immunoscintigraphy with anti-chromogranin A and B monoclonal antibodies (MoAbs) and of 111In-Octreoscan scintigraphy is evaluated in two cases of bronchial carcinoid tumors associated to Cushing syndrome.

Topics: Adolescent; Bronchial Neoplasms; Carcinoid Tumor; Chromogranin A; Chromogranins; Cushing Syndrome; Female; Humans; Indium Radioisotopes; Male; Octreotide; Pentetic Acid; Radioimmunodetection; Radiopharmaceuticals

High numbers of high-affinity somatostatin binding sites have been found on carcinoid tumors, gastrinomas, small cell lung cancers and the majority of medullary thyroid cancers, enabling in vivo visualization of these tumors with octreotide scintigraphy. A comparison of the results obtained at our institution and another 15 centers in Europe show a few remarkable similarities and differences. The overall sensitivity of octreotide receptor scintigraphy to detect the primary GEP tumor and its metastases is high, e.g. 80-90%. The main difference was found in gastrinomas and to a lesser extent in insulinomas. These differences might be attributed to different scanning protocols. Furthermore, octreotide scintigraphy also has a high sensitivity to localize the primary tumor and its metastases causing Cushing's syndrome by ectopic production of ACTH or CRH. Octreotide scintigraphy is a new, sensitive and noninvasive technique to localize somatostatin receptor expressing endocrine tumors and their metastases.

Topics: Carcinoid Tumor; Cushing Syndrome; Gastrinoma; Gastrointestinal Neoplasms; Humans; Indium Radioisotopes; Lung Neoplasms; Octreotide; Pancreatic Neoplasms; Pentetic Acid; Receptors, Somatostatin; Sensitivity and Specificity; Tomography, Emission-Computed, Single-Photon