Extracranial non-vestibular head and neck schwannomas: a case series with the review of literature

Abstract

Introduction: Schwannomas are tumous that arise from Schwann cells. Schwannoma is one of the differential diagnosis for lateral neck swelling.

Objective: In this study, we aim to describe the incidence, presenting clinical features and management of extracranial, non-vestibular schwannomas of head and neck region, along with the review of the literature.

Methods: Patients treated at our tertiary care hospital for head and neck schwannomas for the past 15 years were included in the study. A review of literature on the extracranial head and neck schwannoma was also done.

Results: Twenty-five cases were assessed in this study. Nineteen cases presented as a neck swelling during the initial evaluation. Vagus nerve was the most common nerve of origin, followed by the cervical sympathetic plexus. A rare presentation arising from brachial plexus C5 nerve root was also encountered. A few rare cases of schwannomas arose from the nasal cavity, paranasal sinuses, and oral cavity. Surgical excision was done in all the cases with histopathology suggestive of schwannoma. The nerve of origin of the tumor was identified in nineteen patients. Among them, 11 (58%) were from the vagus nerve, 7 (37%) from the cervical sympathetic chain, and 1 (4%) from the brachial plexus C5 nerve root.

Conclusion: A long-standing unilateral neck mass is the most common presenting complaint in head and neck schwannoma. The diagnosis is mainly based on clinical features and investigations such as imaging. The mainstay of treatment is complete surgical excision. The diagnosis is confirmed on the histopathological study after excision of the lesion. Due to the proximity of the tumor with the involved nerve, palsy may occur. Hence, an accurate preoperative diagnosis of schwannoma is essential.

Keywords: Histopathology; Myelin sheath; Neurilemmoma; Schwannoma; Vagus nerve.

Figure 1

(A) Image showing the axial section of Contrast CT Scan of Vagal Schwannoma. The white arrow pointing towards the right side shows the well-encapsulated schwannoma with cystic change and central enhancing solid component. Vagal schwannoma separates the carotid anteromedially and internal jugular vein anterolaterally. (B) An intraoperative picture of vagal schwannoma is shown by the white arrow pointing towards the right side.

Figure 2

(A) Image showing the axial section of contrast CT scan of Base of Tongue Schwannoma. The white arrow pointing towards the right side shows the schwannoma with stalk attached to the base of the tongue. (B) An intraoperative picture of schwannoma arising from the base of the tongue is shown by the white arrow pointing downwards.

Figure 3

(A) Image showing right-sided brachial plexus schwannoma presenting as swelling in the neck. The lesion is shown by a black arrow pointing towards the left side. (B) Contrast CT scan of brachial plexus schwannoma. A white arrow pointing towards the right side shows the brachial plexus schwannoma, which arises posterolateral to the carotid sheath. (C) Intraoperative picture of brachial plexus schwannoma marked by a black star. Brachial plexus schwannoma is seen deep to sternocleidomastoid. SCM, Sternocleidomastoid; Tr, Trapezius.

Figure 4

(A) The clinical picture of right-sided cervical sympathetic schwannoma shown by a white arrow pointing towards the right side. (B) Axial section of contrast CT scan, showing the cervical sympathetic plexus schwannoma marked with a black star. A black arrow pointing towards the right side shows the Internal jugular vein compressed and displaced laterally. A black arrow pointing downwards shows the carotid, which is pushed anteriorly by the lesion. (C) A star mark shows the intraoperative picture of schwannoma. The black arrow pointing towards the right side shows the Internal jugular vein compressed and displaced laterally. A black arrow pointing towards the left side shows the carotid, which is pushed anteriorly and medially. The Vagus nerve is seen displaced anteriorly, as shown by the black arrow pointing upwards.

Figure 5

Histological picture showing characteristic features of schwannoma consisting of Antony A and Antony B areas. AA, Antony A areas consist of palisading of the nuclei around a central mass of cytoplasm called Verocay bodies. AB, Antony B areas contain a loose stroma with no distinct pattern by the fibres and cells. VB, Verocay Bodies – the central mass of cytoplasm around which nuclei are seen palisading in Antony A areas.