Ann Thorac Surg 2007;84:2088-2090. doi:10.1016/j.athoracsur.2007.06.036
© 2007 The Society of Thoracic Surgeons
Case Reports
Management of an Anterior Mediastinal Pheochromocytoma Causing Tracheomalacia
Bradley G. Leshnower, MDa,
Rohinton J. Morris, MDa,
Taine T.V. Pechet, MDb,*
a Division of Cardiac, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
b Division of Thoracic Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
Accepted for publication June 13, 2007.
* Address correspondence to Dr Pechet, 266 Wright Saunders Bldg, 39th & Market Streets, Philadelphia, PA 19104 (Email: taine.pechet{at}uphs.upenn.edu).
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Abstract
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Thoracic paragangliomas are rare tumors that arise from extra-adrenal chromaffin cells and have the capacity to secrete catecholamines. Surgical excision is the optimal treatment of these tumors as they are resistant to chemotherapy and radiation therapy. Although these tumors are most commonly found in the abdomen, 10% of paraganagliomas are located in the thorax, usually in the posterior mediastinum. Occasionally these tumors present in the anterior mediastinum, which can pose a significant surgical challenge due to the proximity of the great vessels and airway. In this report we describe the treatment of an anterior mediastinal pheochromocytoma that presented with tracheal obstruction and required pulmonary artery reconstruction and airway stenting.
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Introduction
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The paraganglion system consists of chromaffin cells derived from the neural crest that exist outside of the adrenal glands. Tumors arising from these cells are known as paragangliomas, which can be either benign or malignant and may secrete catecholamines. Functional paragangliomas, also known as extra-adrenal pheochromocytomas, are most commonly found in the abdomen at the organs of Zuckerkandl. Ten percent of pheochromocytomas are intrathoracic and tend to arise from the paraganglia associated with the sympathetic chain in the posterior mediastinum [1]. Resection of anterior mediastinal pheochromocytomas can be extremely challenging due to the proximity of the great vessels and airway and may require cardiopulmonary bypass. In this report we present a rare case of an anterior mediastinal pheochromocytoma that presented with tracheal obstruction after an elective parathyroidectomy.
A 45-year-old woman with a past medical history significant for schizophrenia, mental retardation, severe scoliosis, and pulmonic stenosis as a child requiring pulmonary comissurotomy through a median sternotomy presented to an outside hospital for evaluation of persistent nausea and vomiting. The patient was found to be hypercalcemic and was diagnosed with primary hyperparathyroidism. She underwent a parathyroidectomy in which a single enlarged hyperplastic left upper parathyroid gland was removed. After extubation, respiratory distress requiring reintubation developed in the patient. A computed tomographic scan of the chest was obtained that revealed an 8.9 x 11.9 cm mediastinal mass abutting the aortic arch and pulmonary artery, and externally compressing the trachea (Fig 1). The patient was emergently transferred to our institution for further treatment.
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Fig 1. Preoperative computed tomographic scan showing anterior mediastinal pheochromocytoma (PHEO) encasing the (A) aortic arch (ARCH), compressing the trachea (white arrow), and (B) adhering to the bifurcation of the main pulmonary artery (PA).
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On arrival at our institution the patient was taken to the operating room for bronchoscopy and anterior mediastinoscopy. Bronchoscopy revealed tracheomalacia at the level of the mid-trachea with re-expansion of the left and right main stem bronchi distal to the carina. During mediastinoscopy, biopsy of the mass initiated severe hypertension. The diagnosis of anterior mediastinal pheochromocytoma was confirmed when the pathology revealed a paraganglioma and the subsequent metabolic evaluation revealed significantly elevated 24-hour urine levels of norepinephrine (1,560 ug [normal, 0 to 100 ug/d]), epinephrine (60 ug [normal, 0 to 25 ug/d]), vanillylmandelic acid (35.7 mg [normal, 0 to 7 mg/d]), and elevated serum levels of normetanephrine (23.8 nmol [normal, 0 to 0.89 nmol]), metanephrine (1.47 nmol [normal, 0 to 0.49 nmol/L]), norepinephrine (6,882 pg [normal, 80 to 520 pg/mL]), and epinephrine (268 pg [normal, 10 to 200 pg/mL]). The patient also had an elevated serum PTH of 19.1 pmol (normal, 1.6 to 6.9 pmol/L) and a serum calcium of 9.4 mg (normal, 8.5 to 10.5 mg/dL).
After a negative metastatic work-up and 5 days of preoperative catecholamine blockade with metyrosine and phentolamine, the patient returned to the operating room for resection. After a redo sternotomy, the tumor was carefully dissected off of the trachea and aortic arch. As the dissection was carried into the aortopulmonary region, the tumor was found to be tightly adherent to the bifurcation of the main pulmonary artery. Cardiopulmonary bypass was initiated and the tumor was excised en bloc, which required reconstruction of the main pulmonary artery bifurcation with bovine pericardium (Fig 2). All intraoperative frozen margins were negative. On postoperative day 4, the patient was neurologically intact, but failed extubation. Bronchoscopy revealed persistent trachomalacia from the level of the mid-trachea to the carina. She subsequently underwent insertion of a "Y"-shaped airway stent, tracheostomy, and placement of gastrostomy and jejunostomy tubes for enteral nutrition. Postoperative urine and plasma catecholamines, and serum calcium and parathyroid hormone levels normalized. The airway bifurcation stent was removed approximately 3 months later and the patient was discharged to a rehabilitation center ventilating spontaneously and receiving tube feedings.
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Fig 2. Photograph of anterior mediastinal pheochromocytoma after resection en bloc. The scissors are pointing to the area on the tumor located on the lesser curve of the aortic arch.
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The final pathology revealed a malignant pheochromocytoma with a single positive margin taken from the dome of the left atrium, despite the negative intraoperative frozen margin. The surgical specimen also included an additional hyperplastic parathyroid gland. This prompted an investigation into the possibility of a multiple endocrine neoplasia, which was negative. Due to the malignant nature of the tumor, the patient underwent 131I-Metaiodobenzylguanidine scanning, which did not reveal any activity. Adjuvant external beam radiotherapy is planned.
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Comment
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Anterior mediastinal paragangliomas originate from branchiomeric paraganglionic tissue located in the subclavian, intercarotid, coronary, and aorticopulmonary regions [2]. Certain paraganglia are involved in mediating important physiologic chemosensory reflexes such as the carotid body (baroreflex) and aortic body (depth and rate of respiration). The tumor in the present case most likely originated from the aorticopulmonary region due to its tight adherence to the pulmonary artery, encasement of the aortic arch, and compression of the trachea. Similar involvement of the great vessels by tumors originating from the aorticopulmonary paragangila has been previously reported [3, 4].
One of the interesting aspects of this case is the manner in which the tumor was diagnosed. We can only speculate that the tumor had been present for a significant period of time due to its size and degree of tracheal compression, and yet the patient was completely asymptomatic. She exhibited none of the classic symptoms of cough, chest pain, or hoarseness that are associated with large anterior mediastinal tumors, nor any episodes of palpitations, headaches, or sweating, which are the most common presenting symptoms of pheochromocytomas. In this case, tracheomalacia (secondary to chronic compression of the trachea by the tumor) initiated the cascade of events that led to the diagnosis.
The optimal treatment of mediastinal paragangliomas is complete surgical excision, as these tumors are resistant to current chemotherapy and radiation treatment regimens [5]. In a review of 100 cases of anterior and middle mediastinal paragangliomas, Lamy and colleagues [3] showed a significant, long-term survival benefit to complete surgical resection. Those who underwent complete resection had a mean survival of 125 months compared with 72 months in patients who had an incomplete resection. It is unknown if the catecholamine secreting status of the tumor effects survival, because this series only mentioned that "some" of these tumors were functional and did not clearly delineate if these were located in the anterior or middle mediastinum.
The diagnosis of malignant paraganglioma is made solely on the presence of chromaffin tissue in areas where paraganglionic tissue does not exist. There is no standardized protocol on adjuvant therapy for malignant tumors that have been excised or debulked. However, encouraging survival benefits have been observed with 131I-Metaiodobenzylguanidine therapy [6]. Therefore, we recommend an aggressive approach to the management of anterior mediastinal pheochromocytomas with the goal being complete excision. Preoperative imaging with computed tomography and echocardiography may aid in the planned surgical intervention, which may require resection and reconstruction of the great vessels, myocardium, or airway, or a combination thereof with the assistance of cardiopulmonary bypass. If the tumor is determined to be malignant, adjuvant therapy with 131I-Metaiodobenzylguanidine may provide additional survival benefits.
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References
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- Melicow MM. One hundred cases of pheochromocytoma (107 tumors) at the Columbia-Presbyterian Medical Center, 1926–1976: a clinicopathological analysis Cancer 1977;40:1987-2004.[Medline]
- Glenner GG, Grimley GP. Tumors of the extra-adrenal paragnaglion system (including chemoreceptors)Atlas of tumor pathology, second series, fascicle 9. Washington, DC: Armed Forces Institue of Pathology; 1974. pp. 68-69.
- Lamy AL, Fradet GJ, Luoma A, Nelems B. Anterior and middle mediastinum paraganglioma: complete resection is the treatment of choice Ann Thorac Surg 1994;57:249-252.[Abstract/Free Full Text]
- Olson JL, Salyer WR. Mediastinal paragangliomas (aortic body tumor): a report of four cases and a review of the literature Cancer 1978;41:2405-2412.[Medline]
- Lenders JW, Eisenhofer G, Mannelli M, Pacak K. Phaeochromocytoma Lancet 2005;366:665-675.[Medline]
- Rose B, Matthay KK, Price D, et al. High-dose 131I-metaiodobenzylguanidine therapy for 12 patients with malignant pheochromocytoma Cancer 2003;98:239-248.[Medline]
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Abstract
Introduction
