CASE 16886 Published on 16.07.2020

Paraganglioma of the medium mediastinum (chemodectoma)

Section

Chest imaging

Case Type

Clinical Cases

Authors

Guillermo Unzué García-Falces1, Sergio Alonso Charterina2

1Department of Radiology, Complejo Hospitalario de Navarra, Spain. Calle Irunlarrea, 3. 31008. Pamplona. Spain.

2Department of Radiology, Hospital Universitario 12 de Octubre, Spain. Avenida de Córdoba, s/n. 28041. Madrid. Spain

Patient

33 years, male

Categories
Area of Interest Cardiovascular system ; Imaging Technique CT
Clinical History

A 33-year-old man was admitted to our radiology department with dyspnea and chest pain for 4 weeks. No fever nor haemoptysis were revealed. There were no symptoms suggesting increased catecholamine secretion. Serum biochemistry showed no pathological findings. Urine biochemistry depicted normal vanillylmandelic acid levels.

Imaging Findings

Chest X-Ray (PA & lateral) depicted the presence of a left-sided mediastinal mass, probably located in the aortopulmonary window. There were no pleural effusion or pulmonary abnormalities.

CT scan with and without IVC was performed to confirm the findings and rule out other diagnosis.

There were no pathological findings in both lungs.

In basal CT scan, a 10 cm round-shaped lesion located in the aortopulmonary window was observed. It presented well-defined borders.

After IVC administration; lesion revealed heterogeneous peripheral avid enhancement, due to high vascularization. Centre of the lesion was hypodense, and didn’t show enhancement, suggesting central necrosis. Thus, lesion displayed through contact with thymus gland, aorta and pulmonary artery.

Partial resection of the lesion was performed by medium sternotomy. Infiltration of the pericardium, adventitia of aorta and pulmonary arteries and phrenic and recurrent nerves was confirmed.

Discussion

Paraganglioma is a rare tumour of the mediastinum (0.3% of all tumours)1-3. It has a mild female predominance, and the average age at time of diagnosis is 49. It arises from the paraganglia cells placed in the lymphatic ganglia of the autonomic system; which are located in the adrenal medulla, chemoreceptors, vagal body and plexus 1-3. Most of paragangliomas are located in the region of the cardiac plexus (middle mediastinum) or along the aortic sympathetic chain in the costovertebral sulcus (posterior mediastinum). Those located in the posterior mediastinum are easier to resect1. Histologically, they can be indistinguishable from a pheochromocytoma. They display zellballen pattern positive for chromogranin A and vascular stroma of sustentaculum cells (S100 +). It may be difficult to differentiate benign from malign tumours by pathologist 5, 6. Multiple associations have been described; such as Von Hippel Lindau Syndrome, Von Recklinghausen fibromatosis, Carney Triad and MEN I.

Paragangliomas are asymptomatic or display symptoms related to invasion of local structures or hormonal activity 1-3. Non-adrenal paragangliomas are rarely functioning4. IVC CT scan is the most accurate imaging technique for the diagnosis.

CT findings include an hypervascular mediastinal mass, fed by dilated arteries; which shows heterogeneous and avid enhancement after IVC administration. Vascular invasion signs may be present. Feeding arteries generally arise from the internal mammary artery. On MRI, paraganglioma displays mild hyperintensity to adjacent muscle on T1WI, high hyperintensity on T2WI and avid enhancement with contrast. Phrenic, recurrent and vague nerves may be englobed by the lesion. Selective DSA can demonstrate vascular supply, enabling surgical planning. Definite diagnosis can be made by CT scan. Biopsy is unnecessary.

Paraganglioma poses a surgical challenge due to its proximity to essential structures and high vascularization. Complete resection is very difficult. Surgical technique includes previous embolization of feeding arteries, medium sternotomy, partial resection and cardiopulmonary bypass. Alpha and Beta-blockers administration before surgery are necessary if functioning symptoms are present. Radiation and chemotherapy are ineffective. Adjacent structures invasion and active bleeding deteriorate the prognosis.

Mediastinal paragangliomas are rare and arise from the paraganglia cells of the autonomic nervous system. They are either asymptomatic or display invasion of adjacent structures or hormonal activity. Definite diagnosis can be made by CT scan. Biopsy is unnecessary. Complete resection is very difficult and radiation and chemotherapy are ineffective.  Surgery is the therapy of choice, striving whenever possible for complete resection.

Differential Diagnosis List
Paraganglioma of the aortopulmonary window (Chemodectoma)
Castleman disease
Mediastinum haemangioma
Intrathoracic goitre
Final Diagnosis
Paraganglioma of the aortopulmonary window (Chemodectoma)
Case information
URL: https://www.eurorad.org/case/16886
ISSN: 1563-4086