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Schwannoma; Vagus nerve; CT

Clinical History

72 years old man, chronic smoker (20 packs/year), high blood pression under medical treatment for 10 years, who present a dysphonia, dyspnea, and progressive dysphagia for 4 months. A physical examination without abnormality. A cervico-abdominopelvic CT is required.

Imaging Findings

The CT shows a left tracheal mass with a very limited regular contour, hypodense, slightly enhanced after injection of contrast agent, measuring 22x21x45mm. This mass comes into contact with the esophagus without a fatty separation line behind it, and pushes the thyroid forward. The left common carotid artery remains permeable. Also note the asymmetry of the vocal cords (left vocal cord paralysis).

Our patient underwent an ultrasound-guided biopsy with a histological study which came back in favor of a morphological and immunohistochemical appearance of schwannoma (Figures 1-3).

Figure 1: Axial section of a cervico-thoracic CT scan with injection of contrast product showing a hypodense left laterocervical mass which is slightly enhanced after injection of contrast product.

Figure 2: Coronal reconstruction of a cervico-thoracic CT scan showing a hypodense left laterotracheal mass that displaces the common carotid artery but remains permeable.

Figure 3: Axial section of a cervical CT scan with contrast injection showing asymmetry of the left vocal cord.

Under general anesthesia, complete surgical resection of vagus nerve was performed by lateral cervical incision. Anatomical and pathological examination confirmed the diagnosis of vagus nerve schwannoma.

Discussion

Schwannoma is a rare neurogenic benign tumor developed at the expense of nerve sheath, and about one third of schwannomas occur in the head and neck region, vagus nerve schwannoma is an extremely rare tumor [1]. The diagnosis is difficult, it is clinical and radiological, its evocation is not of 1st attention.

The clinical presentation is not pathognomonic. Most often, it is an isolated, asymptomatic, later cervical mass that gradually increases in size.

The size of this mass may lead to pharyngeal compression and nonspecific signs such as pharyngeal discomfort or even odynophagia.

When cervical mass is associated with dysphonia of ipsilateral vocal cord paralysis, vagus nerve shwannoma is more likely to be caused [2]. Imaging plays an important role in determining the size and parapharyngeal location of tumors.

Diagnosis is made anatomopathologically on surgical specimens, in the presence of Schwann cells of different morphology and organization, Immunohistochemistry shows predominant S100 protein expression [3,4].

Complete excision of the tumour is the only way to prevent recurrence. Conservation of the original nerve is often possible, followed by rehabilitation to reduce complications, with an excellent prognosis and rare recurrence.

Final diagnosis

Vagus nerve schwannoma

Differential diagnosis list

Esophageal tumor

Adenopathy

Vagus nerve paraganglioma

1. Chai CK, Tang IP, Prepageran N, FRCSEdin ORL, Jayalakshmi P, et al. (2012) . Med J Malaysia 67: 343.

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2. , , , , , et al. (2013) . Pan African Medical Journal 14: 1.

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3. Behuria S, Rout TK, Pattanayak S (2015) . Ann R Coll Surg Engl 97: 92-97.

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4. Kanatas A, Mücke T, Houghton D, Mitchell DA (2009) . Oncol Rev 3: 107-111.