Cervical schwannomas are benign tumors of peripheral nerves developed from Schwann cells. We report a case of vagus nerve schwannoma associated with a suspicious multiheteronudular goiter initially considered metastatic lymphadenopathy. We then focus on clinical and imaging aspects for this atypical and challenging diagnosis.

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Figure 1. Ovoid and encapsulated mass, pushing the jugular vein outside and the carotid artery inside, in continuity at its two poles with the vagus nerve.

A 46-year-old patient with no history was admitted for the management of multiheteronodular goiter associated with a right lateral neck mass. Clinically, this mass was palpated along the medial border of the sternocleidomastoid muscle. There were no inflammatory skin signs. Cervical ultrasound showed a normal thyroid volume, two suspicious nodules with hypoechoic character, fuzzy boundaries, central vascularization, and microcalcifications on the right side (Ti RADS 5), and a 3rd isoechoic benign nodule of 6.5mm on the left thyroid lobe. A right lateral neck hypoechoic mass was considered as suspicious jugular-carotid lymphadenopathy. The patient was in clinical and biological euthyroidism. A right lobo-isthmectomy was performed for extemporaneous examination. Exploration of the right carotid region showed an ovoid and encapsulated mass, pushing the jugular vein outside and the carotid artery inside, in continuity at its two poles with the vagus nerve (Figure 1). Upon opening of its capsule (Figure 2) the mass was easily dissected from the nerve (Figure 3). Resection of the surplus capsule was then performed (Figures 4, 5). We then completed a left lobo-isthmectomy. The extemporaneous and definitive examination of the thyroid did not show signs of malignancy. The lateral neck mass was a vagus nerve schwannoma. The patient presented right hemilarynx paresis, partially recovered after six months of speech therapy.

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Figure 2. The mass after the opening of the capsule.

Schwannomas constitute less than 1% of the tumors seen in the head and neck region with no significant differences between genders [1]. Around 8–10% of schwannomas undergo malignant transformation. They are seen in all age groups, although more common in the third and fourth decades of life, which is the case of our patient [2, 3].

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Figure 3. Intracapsular enucleation for the mass.

The differential diagnoses for vagus nerve schwannoma presenting a lateral neck mass are paraganglioma, branchial cyst, inflammatory lymphadenopathy, malignant lymphoma, metastasis of upper aerodigestive tract cancers, salivary gland tumors or carotid artery aneurysm [3].

Imaging assessment is beneficial for the diagnosis. However, ultrasound remains non-specific and can be confusing. In our patient, the presence of a hypoechoic mass, associated with suspicious thyroid nodules was wrongly considered as metastatic lymphadenopathy. We didn’t perform further investigations and quickly scheduled the patient for surgery. We should have pre-operatively a CT scan, or an MRI to have an accurate diagnosis and to inform the patient on the high risk of vagus nerve palsy, with all its complications. In CT scan without injection, schwannoma is generally hypodense (in comparison with muscle) taking contrast slightly after injection. In MRI, the tumor appears hypointense in T1-weighted sequences and hyperintense in T2 sequences. Imaging also allows a topographical diagnosis suggesting the nerve from which cancer arises [4]. Some authors use the fine-needle aspiration, which is helpful to confirm the diagnosis.

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Figure 4. Resection of the surplus capsule.

Schwannoma is a benign tumor; the preservation of the vagus nerve remains a significant concern during its surgical management. For this, different techniques are reported in the literature [5]. Carvalho GA et al. conducted a systematic review of all published cases in English of vagus nerve schwannoma [2]. Twenty-two studies were included with a total of 53 patients. Intracapsular enucleation is the most used technique (64.9%), followed by extracapsular resection (32.4%). Tumor reduction surgery was reported in only one patient. The vagus nerve was resected in 4 patients, but in only one patient a termino-terminal suture was performed. The most common postoperative complication is hoarseness (22.6%), with or without other signs (cough, secretions, facial paralysis, and Claude Bernard-Horner syndrome) [2-6].

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Figure 5. Final inspection of the nerve.

According to Valentino J et al., intracapsular enucleation allows the preservation of nerve function 30% more than resection anastomosis [7]. In our patient, we performed intracapsular enucleation preserving the vagus nerve. Hemilarynx paresis with dysphonia and cough were observed. No other signs of vagus nerve paralysis were seen. The patient had speech therapy sessions which led to a significant improvement after six months.

Vagus nerve schwannoma is a benign tumor, but whose treatment can be a source of functional sequelae (paralysis of the vagus nerve). An accurate pre-operative diagnosis is necessary to explain all the risks to the patient. Due to the scarcity of published observations, it is difficult to have recommendations for the best surgical technique. However, most authors report better functional nerve preservation with intracapsular enucleation [8, 9].

The authors declared no conflict of interest. The authors declared that this study had not received any financial support.