Current role of 111In-DTPA-octreotide scintigraphy in diagnosis of thymic masses.

Abstract

AIMS AND BACKGROUND:

Thymic tumors (thymomas and thymic carcinomas) represent 50% of all mediastinal tumors. Thymomas usually express high levels of somatostatin receptors, which enable in vivo imaging with 111In-DTPA-octreotide (OctreoScan®). The aim of this study was to further investigate the role of radionuclide techniques in the diagnosis, staging and follow-up of these tumors.

METHODS:

Eight patients (5 women, 3 men, age range 35-79 years; mean ± SD 56.1 ± 15.8 years) entered the study. In 4 patients, myasthenia gravis was the presenting symptom. 111In-DTPA-octreotide scan was performed within 3 weeks after contrast enhanced CT and/or MRI. Planar and tomographic images were acquired within 24 hours of the injection of 111 MBq OctreoScan. The scintigraphic results were defined in correlation with the histological findings.

RESULTS:

Histology revealed thymoma in 3 patients, thymic carcinoma in 1, insular carcinoma of presumably thymic origin in 1, thymic carcinoid in 1, and thymic hyperplasia in 2 patients. Two thymomas were at stage I, 1 thymoma and 1 thymic carcinoma at stage II, 1 insular carcinoma of presumably thymic origin at stage IV, and 1 thymic carcinoid at stage IV. OctreoScan consistently accumulated in primary and/or metastatic sites of thymic tumors while no radiotracer uptake was detected in the 2 patients with benign thymic hyperplasia. In 1 patient with a very large mediastinal mass (13 cm in largest diameter) and multiple metastatic deposits in the lungs, OctreoScan scintigraphy showed a large area of pathological uptake in the anterior mediastinum and a small area of focal uptake in the cervical-dorsal region of the right lung corresponding to a lymph node expressing somatostatin receptors.

CONCLUSIONS:

OctreoScan is avidly taken up by thymic tumors, enabling the diagnosis of these tumors and a better evaluation of their extension. It does not accumulate in thymic hyperplasia, thus allowing the differential diagnosis between these 2 pathological conditions. In patients affected by myasthenia gravis, OctreoScan scintigraphy can play an important role in characterizing thymic masses.

• Authors: Federica Guidoccio, Mariano Grosso, Marco Maccauro, Federica Orsini, Marzio Perri, Giuseppe Boni, Elena Banti, Gaia Grassetto, Domenico Rubello, Giuliano Mariani, Duccio Volterrani
• Journal: Tumori (Tumori) 2011 Mar-Apr Vol. 97 Issue 2 Pg. 191-5 ISSN: 0300-8916 [Print] United States
• PMID: 21617714 (Publication Type: Journal Article)

Chemical References

• Radiopharmaceuticals
• indium-111-octreotide
• Somatostatin
• Pentetic Acid
• pentetreotide
• Octreotide

Topics

• Adult
• Aged
• Carcinoid Tumor (diagnostic imaging)
• Diagnosis, Differential
• Female
• Humans
• Male
• Middle Aged
• Myasthenia Gravis (diagnostic imaging)
• Neoplasm Staging
• Octreotide (analogs & derivatives)
• Pentetic Acid
• Radiopharmaceuticals
• Somatostatin (analogs & derivatives)
• Thymoma (diagnostic imaging, pathology)
• Thymus Hyperplasia (diagnostic imaging, pathology)
• Thymus Neoplasms (diagnostic imaging, pathology)
• Tomography, Emission-Computed, Single-Photon (methods)
• Tomography, X-Ray Computed