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A Functional, Subcarinal Paraganglioma Adherent to the Left Atrial Wall and Supplied by Large Branches of Coronary and Bronchial Arteries

Authors

Gopika SenthilKumar1, Chris K. Rokkas MD2, Paul L. Linsky MD2, Medical Scientist Training Program1, Department of Cardiothoracic Surgery2, Medical College of Wisconsin, Milwaukee WI

Introduction

Mediastinal paragangliomas (PG) are neuroendocrine masses that account for 0.3% of mediastinal tumors1. Functional PGs (secrete catecholamines) are even rarer with only approximately 50 reported cases in the literature2. We report a unique case of a patient with a symptomatic, functional, subcarinal PG that was adherent to the left atrial wall and supplied by a large branch of the right coronary artery (RCA) and bronchial arteries.

Case Presentation

A 35-year-old male presented to the ED with chest pain, seizures, diaphoresis, and hypertension. ECG revealed prolonged QT interval and T wave abnormalities. A highly vascular 5.7cm subcarinal mass was identified on CTA and Dotatate images; labs showed elevated (>3x normal) levels of norepinephrine, normetanephrine, dopamine, and chromogranin A. He was diagnosed with functional paraganglioma and started on terazosin 1mg BID. The dosage was increased to 6mg BID over a month. The patient was also started on 12.5mg BID metoprolol 3wks after ER visit to control catecholamine-related symptoms and minimize intraoperative catecholamine surges. The subcarinal mass was supplied by a large branch of the RCA and bronchial arteries. Thus, a multi-stage resection was planned: (1) blood vessel embolization to protect the RCA and minimize intraoperative bleeding, (2) robotic-assisted thoracoscopy (RAT) for tumor resection. The RCA was successfully embolized. The bronchial artery was not embolized due to high-grade stenosis of the ostium. While mobilizing the tumor via RAT, the mass was found to be more firmly adhered to the pericardium than suspected based on imaging. To avoid injuring the left atrium, it was decided that an open sternotomy with cardiopulmonary bypass (CPB) would be safer. This was performed the next day, and the tumor and partial left atrial wall were successfully resected. Robotic tumor mobilization greatly increased tumor exposure during the open surgery. Histological examination of the mass revealed a 5.9cm paraganglioma that stained positive for chromogranin, synaptophysin, and S100 and negative for CK AE1/3, confirming the diagnosis of paraganglioma. The patient displayed hemodynamic instability and thus the sternotomy could not be closed until 7 days later. Post-operatively, the patient required temporary respiratory support. He made a full recovery and was discharged 17 days after sternotomy closure, and his labs and symptoms returned to baseline by 4mo post-op.

Discussion

To date, there are only a few reported cases of RAT-assisted resection of posterior mediastinal masses, and none, to our knowledge, were functional PGs with major blood vessel supplies. In 22-30% of patients with posterior mediastinal masses, conversion to open surgery has been reported as a necessary technical step to overcome challenges posed by the difficult anatomical location of the tumors or proximity to cardiac structures3. This case illustrates that a hybrid and multidisciplinary approach involving (1) alpha and beta-blockade, (2) pre-operative embolization of tumor blood supply, (3) RAT-based tumor mobilization, and (4) open resection with CPB can be a safe strategy in the treatment of functional mediastinal PGs that are adherent to cardiac structures and are supplied by major blood vessels. This hybrid approach can help minimize intraoperative bleeding and catecholamine surges while protecting important anatomic structures.

References

  1. Munoz-Largacha, J.A., et al., Incidental posterior mediastinal paraganglioma: The safe approach to management, case report. Int J Surg Case Rep, 2017. 35: p. 25-28.
  2. Andrew G. Marthy, N.S., Sanjay Samy, Lewis Britton, Thomas Fabian, Walter Scott Robotic approach to a subcarinal functional paraganglioma. Respiratory Medicine Case Reports, 2020(In Press, Journal Pre-Proof).
  3. Tugba Cosgun, E.K., Alper Toker, Robotic approach for mediastinal diseases: state-of-the-art and current perspectives. Shanghai Chest, 2018. 2.

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Back to the April 2022 issue of ACP IMpact