Schwannoma of the true vocal fold: a rare diagnosis.

Abstract

Schwannomas of the larynx are rare, benign, slowly growing tumors. When they do occur, they are most often isolated in the aryepiglottic folds or false vocal folds. When a tumor originates in the larynx, it typically causes hoarseness and a globus sensation. As the tumor expands, it may cause dyspnea, stridor, and possibly asphyxiation as a result of the mass effect, In this article, we report an unusual case of a schwannoma of the true vocal fold in a young woman.

Introduction

Neurogenic laryngeal tumors are rare, accounting for approximately 0.1% of all benign tumors of the larynx. (1) These tumors arise from the cells of the peripheral nerve, including Schwann's cells, perineural cells, and fibroblasts, and they can produce schwannomas and neurofibromas. Schwannomas arise from neural crest-derived Schwann's cells; they can originate in any peripheral or cranial nerve except the olfactory and optic nerves, which lack Schwann's cells. Approximately 45% of schwannomas arise in the head and neck region, most often in the parapharyngeal space. (2,3) Schwannomas are well-circumscribed and encapsulated submucosal tumors that are extrinsic to nerve fascicles and thus are easily separated. Recurrence can follow an incomplete resection, but malignant transformation is extremely rare. (4) In this article, we describe a case of an unusual laryngeal schwannoma of the true vocal fold in a young woman.

Case report

In December 2001, a 26-year-old woman with no otherwise significant medical history presented to the office with a 7-year history of hoarseness. She reported that her hoarseness had begun following a severe upper respiratory tract infection. Over the course of the 7 years, the hoarseness would become aggravated by alcohol consumption, smoking, and voice straining, although her overall voice quality did not change. She denied any dyspnea, dysphagia, odynophagia, stridor, or globus sensation.

Flexible fiberoptic laryngoscopy revealed the presence of a large submucosal mass in the right vocal fold; the mass appeared to be cystic in nature (figure 1). Both vocal folds were mobile, and no significant airway compromise was detected. Computed tomography (CT) identified a cystic lesion in the area of the right vocal fold (figure 2). The lesion was contained within the laryngeal framework. No cartilage destruction was evident.

The patient underwent direct suspension microlaryngos-copy and biopsy. Consistent with the findings of the fiber-optic examination, the right vocal fold was seen to bulge into the glottic space. No evidence of subglottic extension was observed. A sickle knife was used to make a linear incision along the right true vocal fold, and microflaps were dissected medially and laterally. Blunt dissection revealed a thick, encapsulated, soft-tissue mass. The tumor was completely excised. The patient was extubated following the procedure, and she remained stable in the recovery room. Histopathologic examination revealed that the lesion was a benign laryngeal schwannoma (figure 3).

Two weeks postoperatively, the patient reported that her voice had progressively improved and that her hoarseness was minimal. Follow-up flexible fiberoptic laryngoscopy revealed that the right vocal fold was healing well, erythema was minimal, and edema was absent. The fold was immobile and fixed in the paramedian position. At the 4-month follow-up, fiberoptic examination revealed that the right fold was almost fully mobile and the airway was patent. No sign of recurrence was evident, and the patient's voice had improved markedly.

Discussion

Schwannomas are rare tumors that are usually found in the false vocal folds and aryepiglottic folds. (5) To the best of our knowledge, only 10 other cases of a schwannoma of the true vocal fold have been documented in the literature. (2,6) These tumors are believed to arise from the internal branch of the superior laryngeal nerve. (1) Schwannomas affect patients in all age groups, and they occur predominately in women. (2) Because these lesions grow slowly, patients often report an insidious onset of symptoms that gradually progresses over the course of years. Patients typically present with hoarseness and a globus sensation; they may later develop dyspnea and stridor secondary to the mass effect of the lesion, In 1997, Gardner et al reported a fatality secondary to asphyxiation, but death from laryngeal schwannoma is extremely rare. (7)

Laryngoscopic examinations have revealed that these tumors often produce a submucosal bulge that obscures the view of the true vocal folds. (4) In our patient, preoperative CT of the neck and laryngoscopic findings were more suggestive of a cystic lesion than a soft-tissue tumor. This illustrates that the diagnosis of schwannoma is based more on histology than on the clinical picture. Schwannomas typically have three histologic characteristics: (1) they are encapsulated, (2) they feature Antoni A and/or Antoni B growth patterns, and (3) they are S-100-positive. (8) The Antoni A growth pattern is characterized by the classically described Verocay bodies, which are an arrangement of spindle cells in compact clusters with palisading nuclei and pooled cytoplasm. The Antoni B growth pattern is characterized by edema and a loose arrangement of spindle cells in a myxoid matrix. (9)

Schwannomas must be distinguished from neurofibromas because the latter are more likely to recur and more likely to undergo malignant transformation (10% of cases). (10,11) Neurofibromas can develop singly or multiply; multiple lesions characterize neurofibromatosis type 1. (10) Unlike schwannomas, neurofibromas are intertwined within the nerve fascicles, which makes surgical removal difficult. The differential diagnosis of a laryngeal schwannoma includes laryngeal cyst, laryngocele, adenoma, chondroma, lipoma, and neurofibroma. (12) Direct laryngoscopy and biopsy are required for diagnosis. However, an overly aggressive endoscopic biopsy may cause scarring and preclude a complete resection of the tumor. With this in mind, Cohen et al recently advised that the biopsy be taken at a site away from any area vital to the voice. (13)

Because laryngeal schwannomas are radioresistant, surgical excision is the treatment of choice. It is important to remove the tumor completely because of the risk of a rapid recurrence that could lead to airway compromise. (4) The size of the tumor dictates the surgical approach. An endoscopic approach is sufficient for smaller tumors, but larger tumors may require an external approach (e.g., lateral pharyngotomy or midline thyrotomy) to achieve complete tumor removal while preserving laryngeal function and the overlying mucosa.

References

(1.) Cadoni G, Bucci G, Corina L, et al. Schwannoma of the larynx presenting with difficult swallowing. Otolaryngol Head Neck Surg 2000; 122:773-4.

(2.) Zbaren P, Markwalder R. Schwannoma of the true vocal cord. Otolaryngol Head Neck Surg 1999; 121:837-9.

(3.) Sanghvi V, Lala M, Borges A, et al. Lateral thyrotomy for neurilemmoma of the larynx. J Laryngol Otol 1999; 113:346-8.

(4.) Rosen FS, Pou AM, Quinn FB, Jr. Obstructive supraglottic schwannoma: A case report and review of the literature. Laryngoscope 2002; 112:997-1002.

(5.) Stanley RJ, Scheithauer BW, Weiland LH, Neel HB III. Neural and neuroendocrine tumors of the larynx. Ann Otol Rhinol Laryngol 1987;96:630-8.

(6.) Tzagkaroulakis A, Stivaktakis J, Nikolopoulos T, et al. Ancient schwannoma of the true vocal cord. ORL J Otorhinolaryngol Relat Spec 2003;65:310-13.

(7.) Gardner PM, Jentzen JM, Komorowski RA, Harb JM. Asphyxial death caused by a laryngeal schwannoma: Acase report. J Laryngol Otol 1997;111:1171-3.

(8.) Enzinger FM, Weiss SW. Benign tumors of the peripheral nerves. In: Enzinger FM, Weiss SW, eds. Soft Tissue Tumors. 2nd ed. St Louis: Mosby, 1988:725-35.

(9.) Cotran RS, Kumar V, Collins T, Robbins SL, eds. Robbins Pathologic Basis of Disease. Philadelphia: W.B. Saunders, 1999:1352-5.

(10.) Cummings CW, Montgomery WW, Balogh K Jr. Neurogenic tumors of the larynx. Ann Otol Rhinol Laryngol 1969;78:76-95. (11.) Elias MM, Balm AJ, Peterse JL, et al. Malignant schwannoma of the parapharyngeal space in von Recklinghausen's disease: A case report and review of the literature. J Laryngol Otol 1993; 107: 848-52.

(12.) Martin PA, Church CA, Chonkich G. Schwannoma of the epiglottis: First report of a case. Ear Nose Throat J 2002;81:662-3.

(13.) Cohen S, Sinacori JT, Courey MS. Laryngeal schwannoma: Diagnosis and management. Otolaryngol Head Neck Surg 2004;130: 363-5.

Jennifer Taylor, BA; Marc Stiefel, MD; Steven Y. Park, MD

From the Department of Otolaryngology, New York Medical College (Ms. Taylor), and the Department of Otolaryngology, New York Eye and Ear Infirmary (Dr. Stiefel and Dr. Park), Brooklyn.

Reprint requests: Steven Y. Park, MD, 41 W. 72nd St., Suite IC. New York, NY 10023. Phone: [phone]; fax: [phone]: e-mail: [e-mail]