대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Posterior mediastinal Paraganglioma (Extraadrenal Pheochromocytoma)

Radiologic Findings

1. Chest radiograph shows a large lobulated mass in left paraspinal area.

2. Enhanced CT scans show an inhomogeneous mass with small areas of calcification in left paraspinal area.

3. The solid portion of the mass is well-enhanced and a dilated vascular structure is identified between descending aorta and the mass. Note the smooth pressure erosion of adjacent vertebral body.

Brief Review

1. Extraadrenal pheochromocytoma is termed paraganglioma that may be benign or malignant.

2. Thoracic paragangliomas are rare: they account only 1-2% of all cases of pheochromocytoma.

3. In the thorax, paragaglioma usually occur in three distinct locations:

1) in the area of aortic arch or main pulmonary artery;
2) in the sympathetic chain in posterior mediastinum; and
3) in or adjacent to the heart.

4. Approximately one third of mediastinal paragangliomas are nonfunctioning and asymptomatic. The remainder show symptoms, sign, and laboratory findings of excess catecholamine production.

5. The various paragangliomas appear similar on chest radiography, CT, and angiography.
They are seen as rounded soft tissue masses that are usually hypervascular and therefore enhance brightly at CT after IV administration of contrast media.
Arteriography reveals enlarged feeding vessels, pathologic vessels with the tumor, and an intense tumor blush.
Radioiodine metaiodobenzylguanidine (MIBG) shows increased activity in paragagliomas and is an useful method of identifying extraadrenal pheochromocytoma.

6. Carney's triad consists of extraadrenal paragaglioma, gastric leiomyosarcoma, and pulmonary chondroma.

7. In some cases, complete surgical excision and cure are possible, but in others local invasion or extensive bleeding during surgery precludes complete excision.
In the latter patients, the neoplasm usually recurs although growth rate is often slow.
Metastases have been documented in about 10% of patients.

References

1. McNeill AD, Groden BM, Neville AM. Intrathoracic pheochromocytoma. Br J Surg 1970;57:457-462

2. Spizarny DL, Rebner M, Gross BH. CT evaluation of enhancing mediastinal masses. J Comput Assist Tomogr 1987;11:990-993

3. Hamilton BH, Francis IR, Gross BH, et al. Intrapericardial paragangliomas: imaging features. AJR 1997;168:109-113

Keywords

Mediastinum, Benign tumor,