|Year : 2015 | Volume
| Issue : 4 | Page : 970-973
A giant vagal schwannoma with unusual extension from skull base to the mediastinum
Shenoy S Vijendra1, Raghavendra A Rao1, Vishnu Prasad1, S Haseena1, M Niprupama2
1 Department of ENT and Head and Neck Surgery, Kasturba Medical College, Manipal University, Mangalore, Karnataka, India
2 Department of Pathology, Kasturba Medical College, Manipal University, Mangalore, Karnataka, India
|Date of Web Publication||15-Feb-2016|
Shenoy S Vijendra
Department of Otolaryngology, Kasturba Medical College Hospital, Manipal University, Attavar, Mangalore - 575 001, Karnataka
Source of Support: None, Conflict of Interest: None
Cervical vagal schwannoma is an extremely rare neoplasm. Middle aged people are usually affected. These tumors usually present as asymptomatic masses. These tumors are almost always benign. Preoperative diagnosis of these lesions is important due to the morbidity associated with its excision. Preoperative tissue diagnosis is not accurate. The imaging modality can be done to assess the extent and for planning the treatment. Surgical excision with preservation of neural origin is the treatment option. Giant vagal schwannomas are extremely rare. Only one case has been reported in the literature till date. There has no reported case of extensive vagal schwannoma from skull base to the mediastinum. Here, we describe the asymptomatic presentation of an unusual appearing giant cervical vagal schwannoma with an extension from skull base to the mediastinum.
Keywords: Mediastinum, schwannoma, skull base, vagus
|How to cite this article:|
Vijendra SS, Rao RA, Prasad V, Haseena S, Niprupama M. A giant vagal schwannoma with unusual extension from skull base to the mediastinum. J Can Res Ther 2015;11:970-3
|How to cite this URL:|
Vijendra SS, Rao RA, Prasad V, Haseena S, Niprupama M. A giant vagal schwannoma with unusual extension from skull base to the mediastinum. J Can Res Ther [serial online] 2015 [cited 2020 Sep 25];11:970-3. Available from: http://www.cancerjournal.net/text.asp?2015/11/4/970/164697
| > Introduction|| |
Cervical vagal schwannomas constitute 2-5% of head and neck neurogenic tumors.  Usually occur in the age group of 20-50 years with no sex predilection.  This tumor often presents as asymptomatic mass when it is small and rarely presents with pain, dysphagia, and hoarseness of voice when it grows larger. Schwannomas with an extension from skull base to the mediastinum are extremely rare. We describe our experience in operating on an unusual looking giant vagal schwannoma with an extension from skull base to the mediastinum which presented without symptoms.
| > Case report|| |
A 35-year-old male patient presented with 3 years history of painless swelling in the right side of the neck. There was no associated hoarseness or dysphagia. Physical examination revealed a 7 cm × 3 cm diffuse, firm, nontender swelling with the smooth surface under the sternocleidomastoid muscle. The swelling extended superiorly from the angle of the mandible to the clavicle inferiorly. Preoperative assessment of the larynx showed normal position and mobility of both vocal cords. Ultrasonography (USG) neck showed large heterogeneous lesion with areas of necrosis noted in the right carotid triangle, compressing and displacing internal jugular vein (IJV) anteriorly. The lesion extended from infra auricular region till retrosternal region without increased vascularity or calcifications. USG guided fine-needle aspiration cytology (FNAC) was done and was inconclusive. Computerized tomography (CT) scan showed elongated hypo dense nonenhancing lesion of about 10 cm × 2 cm × 3 cm in the right anterior triangle which extends superiorly into the carotid space splaying the carotid and jugular vein and inferiorly into the retrosternal space up to the manubriosternal joint [Figure 1].
|Figure 1: Contrast-enhanced computerized tomography scan (axial cuts) showing well-defined hypodense mass (red arrow) with splaying of carotid artery and internal jugular vein|
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As the patient was very much concerned about the cosmetic appearance and very rare possibility of malignant transformation of these kinds of tumors we have decided to go ahead with the surgical excision of the tumor. Surgery was planned after getting the written informed consent from the patient regarding the possibility of intraoperative complications and postoperative vagal paralysis. Trans-cervical excision of the tumor was done under general anesthesia with a horizontal incision in the mid thyroid level. The dissection was carried out beneath the sternocleidomastoid muscle in the carotid triangle. A large fusiform mass of about 20 cm in length was found between the carotid and IJV. Superiorly, the mass was found to be extending to the skull base, and inferiorly mass was extending behind the clavicle up to the manubriosternal joint. The mass resembled uniform nerve thickening rather than a tumor. It was around 2-2.5 cm in diameter [Figure 2].
|Figure 2: Fusiform mass (white arrow) between the carotid (yellow arrow) and internal jugular vein (blue arrow)|
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As, we could not get the adequate plane of dissection between the mass and the nerve, the mass was removed en bloc along with the affected nerve segment. It was difficult to get above and below the superior and inferior limits of the mass as it was extending beyond our surgical confinement. The inferior limit of the mass was delivered out by pulling the nerve superiorly. After excising the inferior part, the superior part was delivered out by pulling the nerve inferiorly, and the tumor was removed in toto [Figure 3]. A giant 20 cm long tumor was removed en bloc [Figure 4]. The surgical wound is closed in two layers after securing vacuum drain.
Histopathological examination confirmed the diagnosis to be benign schwannoma of the vagus microscopically studied section composed of benign appearing cells with hypercellular Antony A with Verocay bodies, hypocellular Antony B, and lymphoid aggregates [Figure 5].
|Figure 5: Microscopic view: Low power view (H and E) showing both hypercellular Antony A and hypocellular Antony B areas (top left), high power view showing Antony A and Antony B (top right), lymphoid aggregate (bottom left)|
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Postoperatively patient developed hoarseness of voice with normal swallowing. There were no signs of aspiration. Postoperative videolaryngoscopic assessment revealed right vocal cord palsy. Patient's voice improved with speech therapy. The patient is on regular follow-up since last 6 months.
| > Discussion|| |
Schwannoma is a benign slowly growing tumor composed of neoplastic cells with the immunophenotype and ultrastructural features of schwann cells. These tumors are generally encapsulated except from the sinonasal tract and nasopharynx.  It is also known as Neurilemmoma coined by Stout in 1935. It can arise from any nerve which has Schwann cells except optic and olfactory nerve as they lack those cells. Most often these tumors are solitary but can occur in multiple areas also. Multiple occurrences are usually associated with Neurofibromatosis II. Head and neck is the most common affected region (25-45%) with the lateral neck being the frequently involved site. ,, Cytogenetic abnormality of loss of chromosome 22 is seen in 50% cases, and those are associated with neurofibromatosis II.
Cervical vagal schwannomas constitute about 2-5% of neurogenic tumors.  Large cervical vagal schwannomas with an extension from skull base to the mediastinum are extremely rare. Only one case of giant vagal schwannoma has been reported with dimensions 6 cm × 8 cm × 13 cm.  Schwannomas involving the skull base (jugular foramen) is uncommon. 
These tumors usually present as asymptomatic masses as in our case, if symptomatic patients will present with hoarseness as the main symptom. The sign usually seen in those cases is unilateral vocal cord paralysis. The reported incidence of preoperative vocal cord paralysis is about 12%. Clinical sign elicited in case of vagal schwannoma is a paradoxical cough on palpating the mass. The presence of this sign together with palpation of mass medial to the sternocleidomastoid should arouse the suspicion of the neurogenic tumor. ,,
The exact preoperative diagnosis is difficult due to its rarity in occurrence and possibility of other common conditions like paraganglioma, branchial cyst, and metastatic lymphadenopathy.  The usefulness of FNAC is controversial. The technique of FNAC is difficult because of its proximity to great vessels. Some of the literature reviews had shown that FNAC is neither sensitive nor specific for diagnosing schwannoma.  The specificity of imaging studies (i.e., CT or magnetic resonance imaging [MRI]) was 38%. MRI is the imaging modality of choice. These tumors frequently appear as well-circumscribed masses with peripheral hyperintense rim and central low intensity on T2-weighted images and lies between the carotid and IJV. MRI also helps to locate the nerve of origin (differentiate vagal origin from the sympathetic chain). The vagal schwannomas displace carotid medially, and IJV laterally, but sympathetic chain schwannomas displace both anteriorly without separating them. Incisional biopsy is not advised because further removal of the mass will be difficult. 
Treatment is mainly surgical excision of the tumor with preservation of the involved nerve segment. In cases where the plane of dissection between the nerve trunk and the tumor is not well delineated, excision of the tumor with the involved nerve segment and end to end anastomosis is indicated.  Another modality of treatment is intracapsular enucleation with preservation of neurological function. Intraoperatively the tumor appears as yellowish masses with a smooth surface. Usually, these masses can be easily delineated from the nerve of origin. Histologically, it exhibits two main patterns - Antoni A and Antoni B. Antony A tissue is represented by verocay bodies. There is palisading of the nuclei about a central mass of cytoplasm. In contrast, Antoni B tissue is a loosely arranged stroma in which the fibers and cells form no distinctive pattern. A mixed picture of both types can exist. Lymphoid aggregate is a characteristic feature. Schwannoma cells are diffusely and strongly positive for S-100 protein in both nuclear and cytoplasmic pattern. Postoperative morbidity associated with these tumor excisions is hoarseness and aspiration due to vagal paralysis.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]