DOI: 10.1148/rg.242035077
RadioGraphics 2004;24:594-597
© RSNA, 2004
Posterior Mediastinal Ganglioneuroma1
Allen Forsythe, MD,
John Volpe, MD and
Richard Muller, MD
1 From the Departments of Radiology (A.F., J.V.) and Pathology (R.M.), Hartford Hospital, 80 Seymour St, Hartford, CT 06102. Received March 25, 2003; revision requested April 30 and received June 25; accepted June 27. Address correspondence to A.F. (e-mail: allenforsythe@yahoo.com).
Index Terms: Mediastinum, neoplasms, 67.3162 • Neuroma, 67.3162
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History
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The patient was a 20-year-old female college student with no medical history who enrolled in a study at the University of Connecticut that assessed the role that genetics plays in muscle development following weight training. The study included initial magnetic resonance (MR) imaging of the thorax prior to a regimen of lifting weights and follow-up MR imaging 3 months later after the regimen of lifting weights. Results of the initial MR imaging in February 2002 were unremarkable. When she returned for the follow-up study in May 2002, a large mass was noted in the posterior mediastinum on the right that was not present on the initial images. Because the images in the study protocol were limited, the patient underwent further diagnostic imaging including chest radiography, chest computed tomography (CT), and MR imaging of the thorax. At the time of diagnosis, the patient exhibited no signs or symptoms.
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Imaging Findings
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The protocol MR imaging performed prior to the muscle study demonstrated a normal thorax (Fig 1).
The initial chest radiograph showed a large right-sided mass that abutted the thoracic spine with no obvious destruction of the adjacent vertebral bodies or posterior ribs (Fig 2). Otherwise, the chest radiograph appeared normal.
Chest CT performed the same day showed a right-sided posterior mediastinal mass that measured approximately 11.0 x 3.7 x 5.9 cm, was well circumscribed, and contained mixed attenuation including areas of fat attenuation as well as calcification. The mass arose in the paraspinal space; it abutted and slightly elevated but did not invade the right main-stem bronchus. Other than showing slight compression, surrounding structures appear unaffected by the mass.
With contrast material, the mass demonstrated mild heterogeneous contrast enhancement (Fig 3). There was no mediastinal lymphadenopathy, and the remainder of the examination results were normal. The differential diagnosis for these CT findings includes a benign or malignant tumor of neural origin, mature teratoma (1), sarcoma, and lymphoma. The absence of mediastinal lymphadenopathy or other significant findings in the thorax made the diagnosis of lymphoma less likely. However, Castleman lymphoma has been described as a solitary posterior mediastinal mass (2). Other rare neoplasms have also been described and should be considered, including intrathoracic desmoid (3), granular cell tumor (4), gastrointestinal stromal tumor (5), carcinoid (6), and intrathoracic goiter (7). In addition, inflammatory conditions such as Wegener granulomatosis may occur in the posterior mediastinum (8).
Because of the possibility of a tumor affecting or arising from spinal elements, contrast-enhanced MR imaging of the thorax was performed. T1-weighted images showed a mass of mixed signal intensity with the same morphology as demonstrated at thoracic CT. T2-weighted images demonstrated slight heterogeneous high signal intensity (Fig 4). Again, the mass arose in the paraspinal space and compressed surrounding structures rather than invading them. With contrast material, low-level heterogeneous enhancement was present throughout the mass. These findings were consistent with the CT findings. The differential diagnosis remained the same, with the three most likely diagnoses being neoplasm of neural origin, sarcoma, and lymphoma.
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Pathologic Evaluation
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Subsequent to imaging, the patient underwent a core needle biopsy of the mass, which demonstrated a proliferation of bland spindle cells with a collagenous stroma. Immunohistochemical staining was positive for S-100 and neurofilament, two markers for tumors of nerve sheath origin. In this small sample, there was no evidence for malignancy, such as cellular atypia or prominent mitoses.
After the core biopsy, the patient was scheduled for surgery to remove the mass. The thoracic surgeon who performed the surgery took a right posterior intercostal approach. After the surgeon collapsed the right lung, the mass was immediately visible and appeared heterogeneously pink to red. The tumor was tightly attached to the vertebral column, and significant effort was required to remove it in its entirety.
The gross specimen measured 10.5 x 7.2 x 4.2 cm and weighed 165 g. The nodular tumor mass was well encapsulated (Fig 5). The cut surfaces were tan-white with focal central hemorrhage and calcification.
Microscopic evaluation of the tumor showed the typical findings of a ganglioneuroma, including mature, well-differentiated ganglion cells; uniform spindle cells with small nuclei; and a collagenous stroma (Fig 6). There were no features of malignancy such as hypercellularity, tumor cell necrosis, or cytologic atypia. Mitoses were not present.
The mixed attenuation seen at CT resulted from the areas of degeneration and calcification mixed with other homogeneous areas of the spindle cells. The lack of significant neovascularity accounted for the relatively weak contrast enhancement seen at CT and MR imaging.
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Discussion
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Ganglioneuromas are benign tumors that originate from neural crest cells that make up the sympathetic ganglia along the spinal column and adrenal glands. They arise from the nerve ganglion cells, as opposed to the neuroendocrine (pheochromocytoma) tumors and nerve sheath (schwannoma) tumors (9). Ganglioneuromas share a common histogenic lineage with ganglioneuroblastoma and neuroblastoma and represent the most benign and differentiated of this group (10). Ganglioneuromas typically are well-encapsulated masses with a fibrous capsule that arise in the posterior mediastinum.
These tumors occur most commonly in young patients and represent the most common tumor arising in the posterior mediastinum in this age group (11). Ganglioneuromas may also arise in the retroperitoneum, adrenal gland, and retropharyngeal soft tissues. Patients are usually asymptomatic but may present with labile hypertension and flushing, as these tumors may produce excessive catecholamines (11). Unlike the case with neuroendocrine tumors, catecholamines are metabolized in the tumor, and this fact probably accounts for the relative lack of symptoms seen in these patients. Ganglioneuromas have also been associated with a syndrome of chronic diarrhea, which is usually found in children and is possibly mediated by vasoactive intestinal peptide (12). This symptom as well as hypertension resolve after removal of the tumor. Patients may also present with nonspecific chest pain or symptoms arising from compression of the tracheobronchial tree.
For benign tumors of the posterior mediastinum, surgery is the treatment of choice. Although these tumors are histologically benign, they may behave aggressively and compress or invade local neural foramina as well as adjacent mediastinal structures. Given this potential, these tumors are resected. To our knowledge, no medical treatment for ganglioneuroma has been described. The recurrence rate for ganglioneuroma is near zero, and postoperative complications are rare.
Much like in this case, ganglioneuromas are diagnosed incidentally during imaging studies performed for other reasons. When they are found, initial imaging studies allow distinction between benign and malignant forms of neuroganglion cell tumors, although their imaging characteristics overlap. The age at presentation and the clinical behavior of the tumor may also help one make an accurate diagnosis. However, this case suggests that a benign ganglioneuroma may act aggressively not only in the rate of its growth but also in its relationship to surrounding structures. Benign, well-encapsulated tumors typically respect adjacent structures. However, in this case the tumor was tightly attached to the vertebral bodies, raising the suspicion of a malignant histology. Fortunately, the tumor was benign. The patient did well postoperatively without complications and continues to be asymptomatic.
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References
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- Sinclair DS, Bolen MA, King MA. Mature teratoma within the posterior mediastinum. J Thorac Imaging 2003; 18:53-55.[CrossRef][Medline]
- Fukino S, Fukata T, Hayashi E, et al. Castleman lymphoma originated from the posterior mediastinum resected thoracoscopically: report of a case. Kyobu Geka 2002; 55:519-522. [Japanese].[Medline]
- Kocak Z, Adli M, Erdir O, Erekul S, Cakmak A. Intrathoracic desmoid tumor of the posterior mediastinum with transdiaphragmatic extension: report of a case. Tumori 2000; 86:489-491.[Medline]
- Machida E, Haniuda M, Eguchi T, et al. Granular cell tumor of the mediastinum. Intern Med 2003; 42:178-181.[Medline]
- Lee JR, Anstadt MP, Khwaja S, Green LK. Gastrointestinal stromal tumor of the posterior mediastinum. Eur J Cardiothorac Surg 2002; 22:1014-1016.[Abstract/Free Full Text]
- Horie Y, Kato M. Neuroendocrine carcinoma of the posterior mediastinum: a possible primary lesion. Arch Pathol Lab Med 1999; 123:933-936.[Medline]
- Specker R, Curti G, Muller W, Stulz P. Intrathoracic goiter: a rare mediastinal tumor. Swiss Surg 2001; 7:134-138. [German].[CrossRef][Medline]
- Feigin DS, Siegelman SS, Theros EG, King FM. Nonmalignant lymphoid disorders of the chest. AJR Am J Roentgenol 1977; 129:221-228.[Abstract]
- Ronson RS, Duarte I, Miller JI. Embryology and surgical anatomy of the mediastinum with clinical implications. Surg Clin North Am 2000; 80:157-169.[CrossRef][Medline]
- Rubin E, Farber J. Pathology 3rd ed. Philadelphia, Pa: Lippincott-Raven, 1999.
- Geoerger B, Hero B, Harms D, Grebe J, Scheidhauer K, Berthold F. Metabolic activity and clinical features of primary ganglioneuromas. Cancer 2001; 91:1905-1913.[CrossRef][Medline]
- Index of suspicion. Pediatr Rev 2002; 23:25-33.[Free Full Text]
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Additional Reading
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Lonergan GJ, Schwab CM, Suarez ES, Carlson CL. Neuroblastoma, ganglioneuroblastoma, and ganglioneuroma: radiologic-pathologic correlation. RadioGraphics 2002; 22:911-934.[Abstract/Free Full Text]
Scherer A. Imaging diagnosis of retroperitoneal ganglioneuroma in childhood. Pediatr Radiol 2001; 31:106-110.[CrossRef][Medline]
Townsend CM. Sabiston textbook of surgery 16th ed. Philadelphia, Pa: Saunders, 2001.
Weber AL, Montandon C, Robson CD. Neurogenic tumors of the neck. Radiol Clin North Am 2000; 38:1077-1090.[CrossRef][Medline]
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History
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