|Year : 2018 | Volume
| Issue : 3 | Page : 687-689
Glottic neurogenic tumor: A highly uncommon site for schwannomas
Shuchita Singh1, Rakesh Kumar1, Maitrayee Roy2, Asit Ranjan Mridha2
1 Department of Otorhinolaryngology, All India Institute of Medical Sciences, New Delhi, India
2 Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
|Date of Web Publication||12-Jun-2018|
Dr. Shuchita Singh
ENT Office, Room No. 4057, 4th Floor, Academic Section, All India Institute of Medical Sciences, New Delhi - 110 029
Source of Support: None, Conflict of Interest: None
Schwannomas are benign encapsulated neurogenic tumors, arising from Schwann cells embedded in neurilemal sheath as multinucleated syncytial network. Head and neck schwannomas account for 25%–45% of all schwannomas, majority developing in parapharyngeal space. Laryngeal schwannoma in itself is a rarity, and a glottic origin further complicates its diagnosis. To the best of our knowledge, this is the second case of glottic schwannoma being reported in medical literature. Symptomatology is attributable to mass effect of a slow-growing laryngeal tumor, ranging from sore throat to stridor. The gold standard method for their excision is still debatable. For small tumors, endoscopic or direct laryngoscopic approach is preferred, but for large glottic tumors, external approach is advocated for better exposure and facilitating mucosal grafting. Index case is being presented not only for its rare site of origin, but also to stress on the importance of meticulous histopathological examination to advocate appropriate treatment.
Keywords: Glottic, schwannoma, surgery
|How to cite this article:|
Singh S, Kumar R, Roy M, Mridha AR. Glottic neurogenic tumor: A highly uncommon site for schwannomas. J Can Res Ther 2018;14:687-9
| > Introduction|| |
Schwannomas are benign encapsulated neurogenic tumors, originating from Schwann cells embedded in neurilemal sheath as a multinucleated syncytial network. Almost, 25%–45% of all schwannomas occur in head and neck region, majority developing in parapharyngeal space. Laryngeal schwannoma in itself is a rarity, its diagnosis being further complicated by the rare site of its origin in glottis.
Shouchnek et al. credited with the first documentation of laryngeal schwannoma in 1925. The rare nature of this tumor can be assessed by the fact that since its description in 1925, around 135 cases have been documented in English literature so far. The most common site for laryngeal schwannoma is supraglottis. Glottis is an extremely rare site for its origin with index case being second case reported in medical literature so far to the best of our knowledge.
Symptomatology is generally related to mass effect of a slow-growing laryngeal tumor, ranging from sore throat and odynophagia to stridor. Airway compromise occurring due to this glottic tumor mandates surgical resection. The optimal method for excision of such tumors is still debatable. For small lesions, endoscopic or direct laryngoscopic approach is preferred, but for large glottic tumors, an external approach, laryngofissure, is advocated for adequate exposure.
| > Case Report|| |
A 38-year-old male presented to the Department of Otorhinolaryngology, in a tertiary care center with the complaints of hoarseness for the past 2 years, which was insidious in onset and gradually progressive, interfering with his daily life. The symptoms had worsened for the past 10 months, progressing to respiratory distress. He had no complaints of odynophagia, dysphagia, hemoptysis, or hematemesis.
A flexible laryngoscopic evaluation showed a mucosa-covered pedunculated lesion occupying anterior 1/3–1/2 of the under surface of left true cord and subglottic region, measuring 2 cm in diameter and occluding approximately 50% of airway [Figure 1]. Bilateral vocal cords were mobile with left cord mobility slightly hampered due to mass effect. Computed tomography (CT) scan revealed a homogeneously enhancing, well-defined, encapsulated intraluminal polypoidal mass arising from under surface of left cord, with no evidence of any cartilage destruction or extralaryngeal spread or lymph node involvement [Figure 2]. Direct laryngoscopic evaluation with biopsy was done to confirm findings of fiber-optic laryngoscopy. On histological examination of biopsy, the features were consistent with benign nerve sheath tumor.
|Figure 1: Mucosa-covered swelling in anterior 1/3–1/2 of the under surface of left true cord and subglottic region, measuring 2 cm in diameter|
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|Figure 2: Axial cuts of the contrast enhanced computed tomography neck showing a homogeneously enhancing, well-defined, encapsulated intraluminal polypoidal mass arising from the under surface of the left cord, with no evidence of any cartilage destruction or extralaryngeal spread|
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Taking into account the spindle cell proliferation, both benign and malignant conditions of the epithelial and mesenchymal lesions were considered. Based on the morphological findings along with the histopathological diagnosis and owing to small size and pedunculated nature of lesion, the patient was planned for transoral CO2 laser excision of glottic schwannoma. There was a 2 cm × 1.5 cm smooth mucosa covered pedunculated lesion arising from under surface of left cord extending to subglottis with no overlying ulceration. The histopathology revealed a spindle cell tumor exhibiting interlacing fascicular pattern with varying degrees of focal nuclear palisading without nuclear pleomorphism or mitosis. Immunohistochemistry showed positivity for S-100 and negativity for CD 34, vimentin and alpha-smooth muscle actin, consistent with benign nerve sheath tumor. As the postoperative histopathological evaluation revealed a benign pathology with no underlying invasion, no further treatment was warranted.
The patient's postoperative course was uneventful. He still remains to be asymptomatic with no evidence of disease after 8 months of surgery.
| > Discussion|| |
Approximately, 25%–35% of all reported schwannomas occur in head and neck. Laryngeal neurogenic tumors are rare, comprising 0.1%–1.5% of all benign laryngeal tumors. Most common neurogenic tumors of larynx include schwannoma and neurofibroma. Schwannomas have a slight female preponderance  and can occur at any age  with an increased incidence in the sixth and seventh decades of life. Since its first description in 1925 by Shouchnek, fewer than 140 cases have been reported in literature  so far. Even in larynx, almost all benign neurogenic tumors arise in the supraglottic region; though they can develop in glottis and subglottis in extremely rare cases. Most common nerve of origin of laryngeal schwannoma is internal branch of superior laryngeal nerve, rarely arising from branches of recurrent laryngeal nerve.
Symptomatology is attributable to a slow growing tumor, presenting with obstructive airway features, occasionally, presenting with other complaints such as hoarseness, dysphagia, wheezing, hemoptysis, or even fever due to pulmonary infection. Diagnosis is often delayed owing to the insidious onset and nonspecific clinical features.
Diagnostic armamentariums applied for laryngeal tumor are fiber optic laryngoscopy and radiology in form of CT scan and magnetic resonance imaging (MRI) to evaluate the exact site, size, and extent of lesion. In cases of infants and young children, CT scan is considered a better option than endoscopic examination and MRI, as both require general anesthesia or deep sedation yielding considerable risk.
Previous studies have mentioned “pseudo-fixation” to be a cause of apparent fixation of ipsilateral cord. In the present case, tumor arose from under surface of left true cord, so did not classically exhibit “pseudo-fixation,” though the mobility of ipsilateral cord was minimally restricted. Characteristic CT findings of laryngeal schwannoma include a well-defined heterogeneously enhancing encapsulated mass lesion in larynx with no evidence of infiltration into the underlying muscle or cartilage erosion. The impairment in the mobility of the cord has been attributed to the mass effect of the lesion.
Histopathology remains as gold standard for establishing diagnosis. A triad of histological features has been established by Enger and Weiss  as a diagnostic criteria including the presence of capsule, presence of Antoni A and/or Antoni B stroma, and positive staining for S-100.
In the present scenario, multiple punch biopsies of the lesion were taken, which ruled out any metastatic disease and suggested a diagnosis of schwannoma. It is empirical that we distinguish a schwannoma from a neurofibroma as recurrence rate and malignant transformation in the latter is greater as compared to schwannoma. Therefore, after a definitive diagnosis of a schwannoma, limited resection such as enucleation can be sufficient.
Owing to the rare location of this pathology, no clear cut agreement regarding best conservative surgical procedure for glottic lesions has been designed. Various surgical approaches have been advocated for laryngeal schwannomas, ranging from endoscopic removal to laryngofissure and anterior and lateral pharyngotomies to lasers. Mainstay of treatment for tracheal tumors is surgical resection with tracheal reconstruction. For small, pedunculated glottic tumors, successful transoral endoscopic resection using a CO2 laser has been reported to prevent recurrence, though some studies have documented recurrences as well. Radiotherapy is not used as these nerve sheath tumors are highly radioresistant.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]