Schwannoma of the Recurrent Laryngeal Nerve: A Rare Entity

de Heer, Linda M. PhD; Teding van Berkhout, Ferdinand PhD; Priesterbach-Ackley, Loudy P. MD; Buijsrogge, Marc P. PhD

Innovations: Technology & Techniques in Cardiothoracic & Vascular Surgery: January/February 2017 - Volume 12 - Issue 1 - p 64–66
doi: 10.1097/IMI.0000000000000334
Case Reports

Abstract: Neurogenic tumors are the most common posterior mediastinal tumors in adults. Schwannomas originating from the recurrent laryngeal nerve are rare. The present study describes a 46-year-old man with a tumor in the left superior mediastinum. Because of the narrow relationship with the aorta and the left pulmonary artery, the tumor was excised by left-sided minithoracotomy. The tumor, a schwannoma, originated from and encased the left recurrent laryngeal nerve. Six months after surgery, the patient was free of recurrence without symptoms other than hoarseness. “Additional imaging by magnetic resonance imaging could raise the probability of a neurogenic origin of the mass, eventually leading to collaboration with the neurosurgeon in this case.”

From the Departments of *Cardiothoracic Surgery, †Pulmonology, and ‡Pathology, University Medical Central Utrecht, Utrecht, The Netherlands.

Accepted for publication September 26, 2016.

Disclosure: The authors declare no conflicts of interest.

Address correspondence and reprint requests to Linda M. de Heer, PhD, Department of Cardiothoracic Surgery, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands. E-mail: L.M.deheer-2@umcutrecht.nl.

Article Outline

Neurogenic tumors are the most common type of posterior mediastinal tumors in adults.1 They may also appear in the middle and superior mediastinum. The tumors originate from cells of the nerve sheath or from the ganglionic cells of the spinal ganglia or from the autonomic, paraganglionic and parasympathetic systems.1

The subtype schwannoma is a benign nerve sheath tumor, which is often located in the head, neck, and extremities. Most of the patients with a schwannoma are asymptomatic. However, occasionally, the tumor may present with symptoms of compression of neighboring structures.1 A schwannoma arising from the recurrent laryngeal nerve is a very rare entity.2,3 The present report describes a case of a recurrent laryngeal nerve schwannoma in the left superior-posterior mediastinum, which was surgically resected via a left minithoracotomy.

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CASE REPORT

A 46-year-old man presented to the pulmonologist with a persistent and productive cough for 1.5 years, without hoarseness. The medical history was uneventful. Physical examination, laboratory results, and an x-ray of the sinuses revealed no abnormalities. A chest x-ray showed a well-defined mass located in the aortopulmonary window. In retrospect, two chest x-rays (at 5 and 2 years ago) confirmed a growing mass in the aortopulmonary window (Fig. 1). Contrast-enhanced computed tomography of the chest showed a sharply demarcated, inhomogeneous circumscribed mass in the left superior mediastinum, with a superior limb into the anterior mediastinum and a maximum diameter of 27 mm of unknown origin (Fig. 2). The differential diagnosis of the radiologist and the panel of pulmonologists and cardiothoracic surgeons during the multidisciplinary decision making consisted of a thymoma, lymph node, or germ cell tumor, the classical “anterior mediastinal mass” differential diagnosis.

The patient underwent a left-sided video-assisted thoracoscopic procedure (VATS) for excision biopsy of the mass. After introduction of the scope, a tumor with a round shape with a branch to the anterior mediastinum was identified in the left superior mediastinum in close relationship with the left pulmonary artery and the aortic arch and descending aorta. For optimizing exposure and dexterity, the VATS was converted to an open minithoracotomy procedure. The tumor was originating from and completely obliterating the recurrent laryngeal nerve. The tumor was completely excised, and the upper limb was clipped and transected at the level of the left subclavian artery.

Gross pathological inspection revealed a mass with a complete envelope and a partly inhomogeneous aspect at the cut surface. Histologically, the tumor contained hypercellular fields of bundled spindle cells as well as hypocellular myxoid areas and was diagnosed as a schwannoma of the recurrent laryngeal nerve (Fig. 3).

Postoperative recovery was uneventful, and the patient was discharged on the fifth postoperative day. After the surgical procedure, the cough disappeared, but hoarseness was present. The otorhinolaryngologist diagnosed a left vocal cord paralysis. At 6-month follow-up, the patient was tumor free, but the hoarseness persisted.

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DISCUSSION

Schwannoma, also known as neurilemmoma, is a benign nerve sheath tumor, arising from the Schwann cells. Approximately 10% of the schwannomas originate from the vagus nerve. The tumor may occur at all ages without a sex preference. It is asymptomatic in most cases. Symptoms (ie, chest pain, coughing, hoarseness, and dysphagia) may occur because of involvement of the nerve in the tumor.1 Hoarseness may occur preoperatively or postoperatively when the tumor is associated with the recurrent laryngeal nerve, as was shown in the present case. Schwannomas of the recurrent laryngeal nerve are twice as likely to be located on the left side of the chest than on the right, because the recurrent laryngeal nerve arises lower in the left thoracic cavity and the left nerve trunk is thicker.4 In this case, the imaging results were inconclusive and the differential diagnosis did not include a schwannoma. With the probability of a neurogenic origin of the tumor in mind, nerve-sparing surgery together with the neurosurgeon probably could have been performed.2 From literature, it is known that computed tomography and magnetic resonance imaging reveal valuable information regarding the location and origin of the tumor as well as aiding surgical planning, and thus, it should be recommended. As a future prospect, positron emission tomography is mentioned as a modality with possibilities to discriminate a schwannoma from other common cystic lesions.2

Surgical resection is recommended for neurogenic tumors in the mediastinum. Video-assisted thoracoscopic procedure of vagal nerve schwannomas is described in several case reports4 as the preferred procedure for the resection of sharply marginated masses. Concerns for VATS resection of vagal nerve schwannomas are tumor larger than 6 cm and a location in the aortopulmonary window.4 During resection of the tumor, encasing the vagal nerve, the patient should be closely observed for severe cardiac rhythm abnormalities, that is, bradycardia or asystole. Nerve-sparing surgery is described for head and neck schwannomas but not yet for recurrent laryngeal nerve schwannomas.5

The prognosis of the patient in this case seems to be satisfactory. However, long-term survival should be assessed.

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REFERENCES

1. Shields TW, Reynolds M. Neurogenic tumors of the thorax. Surg Clin North Am. 1988;68:645–668.
2. Knulst R, Bosman WM, Ritchie ED, Da Costa A. Cystic schwannoma of the recurrent laryngeal nerve: a rare finding posing diagnostic difficulties. BMJ Case Rep. 2014;2014 doi: 10.1136/bcr-2014-203873.
3. Sasaki K, Kohno T, Mun M, Yoshiya T. Thoracoscopic removal of middle mediastinal schwannoma originating from recurrent nerve. Thorac Cardiovasc Surg. 2008;56:375–377.
4. Menal Muñoz P, García Tirado FJ, Rivas de Andrés JJ. Intrathoracic vagal nerve schwannoma. Arch Bronconeumol. 2011;47:374–375.
5. Battoo AJ, Sheikh ZA, Thankappan K, Hicks W, Iyer S, Kuriakose MA. Nerve-sparing subcapsular resection of head and neck schwannomas: technique evaluation and literature review. J Laryngol Otol. 2013;127:685–690.
Keywords:

Schwannoma; Recurrent laryngeal nerve; Thoracotomy

©2017 by the International Society for Minimally Invasive Cardiothoracic Surgery