대한비과학회

Clinical Experience of Sinonasal Schwannomas

Sung-Moon Hong, MD

, Jae-Min Shin, MD

, Il-Ho Park, MD, PhD

, Seung Hoon Lee, MD, PhD

, Yong-Dae Kim, MD, PhD

and Heung-Man Lee, MD, PhD

From

Department of Otorhinolaryngology-Head and Neck Surgery,

Biomedical Sciences,

3

Institute for Medical Devices Clinical Trial Center, Korea University College of Medicine, Seoul, South Korea

4

Department of Otorhinolaryngology-Head and Neck Surgery, Yeungnam University College of Medicine, Daegu, Korea

ABSTRACT

Background : Schwannomas are benign tumors of ectodermal origin derived from Schwann cells of the nerve sheath. Approximately less than 4% of these tumors are found in the paranasal sinuses and there has been little in- formation reported concerning the presentation and surgical management of sinonasal schwannomas. The purpose of this study was to analyze the clinical data, management, and long-term outcomes of sinonasal schwannomas.

Methods : Retrospective chart review of patients with sinonasal schwannomas treated from January 2001 to March 2012 was performed. Clinical data and follow-up information were obtained from a review of the patients’

charts and the operative, anesthesia, and pathology reports. Results : There were 4 females and 4 males included in this study. The mean age was 37.5 years (range, 22-51 years). The mean tumor size was 3.1 cm (range 1.0-6.0 cm). The origin of the tumors included: nasal septum (n = 2), nasal vestibule (n = 2), pterygopalatine fossa (n = 2), ethmoid sinus (n = 1), and inferior turbinate (n = 1). Seven patients had endoscopic resections and one patient with a schwannoma in the nasal vestibule underwent a sublabial approach. The mean follow-up was 59 months.

There were no tumor recurrences during the study period. Conclusions : Schwannomas in sinonasal cavity can be treated effectively with the endoscopic approach with minimal morbidity and long-term disease control.

KEY WORDS : Schwannoma · Sinonasal · Endoscopic Surgery · Nasal Tumor.

INTRODUCTION

Schwannomas are benign tumors that develop from the schwann cells of peripheral nerves. Approximately 45% of Schwannomas occur in the head and neck region.

Schwannomas of the sinonasal tract are very rare, repre- senting less than 4% of schwannomas arising in the head and neck.

The clinical presentation of a nasal or paranasal schwannoma is indistinguishable from any other tumors in this region. The signs and symptoms usually depend on the location and size of the tumors.

Little information is available in the literature concerning the clinical aspects and management of sinonasal schwannomas beyond in- dividual case reports. We present a series of 8 cases of sinonasal schwannomas and review the characteristics of

schwannomas of the sinonasal tract.

Patients and methods

Retrospective chart review of patients with sinonasal schwannomas treated from January 2001 to March 2012 was done in two University Hospitals (Korea Universi- ty, Yeungnam University). Eight patients with sinonasal schwannoma were included in this study. Clinical data and management information were obtained from clin- ic charts, operative, anesthesia and pathology reports.

Pubmed search was done with key words, ‘sinonasal’ and

‘schwannoma’. Previous case reports were reviewed and summarized.

Results

Demographics

Tumor location, size and demographic data are de- scribed in Table 1. There were 4 women and 4 men in this study. The mean age was 37.5 years (range 22 - 51). The Address correspondence and reprint requests to Heung-Man Lee, MD,

PhD, Department of Otorhinolaryngology–Head and Neck Surgery, Guro Hospital, Korea University College of Medicine, 80 Guro-dong, Guro-gu, Seoul 152-703, South Korea

Tel: +82-2-2626-3185 · Fax: +82-2-868-0475 E-mail: [email protected]

Received for publication on January 15, 2013 Accepted for publicatoin on May 19, 2013

- 26 -

mean tumor size was 3.1 cm (range 1.0 - 6.0 cm). There was no medical history related to the schwannoma. Most common symptom was nasal obstruction followed by fa- cial numbness, epistaxis and orbital swelling. Mean symp- tom duration was 13 months (range 1 - 36). The origins of the tumors included nasal septum (2), nasal vestibule (2), pterygopalatine fossa (2), ethmoid sinus (1) and inferior turbinate (1).

Diagnostic findings

Nasal endoscopy showed a smooth, polypoid tumor in nasal cavity (Fig. 1). Computed tomography of paranasal sinuses showed heterogeneously enhanced mass (Fig. 2).

Magnetic resonance imaging of paranasal sinuses showed an intermediate signal intensity on T1-weighted images and intermediate to high signal intensity in T2-weighted images (Fig. 3).

Surgical approaches

Seven patients had endoscopic resections and one pa- tient with schwannoma in nasal vestibule underwent sub- labial approach. Complete excision was done in all cases and there was no complication after surgery.

Pathologic findings

bundles, sometimes resembling a palisade. Immunohis- tochemical study showed positive for S-100 protein (Fig. 4).

Follow-ups

The mean follow-up was 59 months. There were no tu- mor recurrences during the study period.

Discussion

Schwannoma is a benign tumor which occurs in the schwann cell. It is known to arise in a nerve and grow while unilaterally displacing rather than invading a nerve

Table 1. Clinical findings of eight patients with sinonasal schwannoma.

Pul TB: pulmonary tuberculosis, R: right, L: left

Fig. 1. Nasal endoscopic findings of sinonasal schwannomas originated from inferior turbinate (A) and nasal septum (B) shows smooth polypoid mass in nasal cavity.

NS: nasal septum, MT: middle turbinate, IT: inferior turbinate

A B

A B

Fig. 2. Computed tomography of paranasal sinuses (axial scan) shows heterogeneously enhanced lesions. Schwannomas are originated from nasal septum (A), pterygopalatine fossa (B), anterior ethmoid sinus (C) and inferior turbinate (D).

C D

No. Sex Age

(Years) Medical history Symptom

(months) Size(cm) Side Site Approach Follow-up

(months)

1 M 27 None Nasal obstruction (5) 6 x 5 L Nasal septum Endoscopic 63

2 M 51 None Nasal obstruction (6) 1.6 x 1.3 L Nasal septum Endoscopic 36

3 M 41 None Right facial pain and numbness (1) 3.5 x 3 R Pterygopalatine fossa Endoscopic 15

4 F 50 Brain rumor,

Thyroid PTC Nasal obstruction (36) 5 x 6 R Pterygopalatine fossa Endoscopic 86

5 F 22 None Mass in vestibule (36) 1 x 1.5 R Nasal vestibule Sublabial 18

6 M 32 Pul tb Frequent epistaxis (7) 1.1 x 1.2 L Nasal vestibule Endoscopic 15

7 F 45 None Right orbital swelling (12) 1.0 x 1.2 R Ethmoidal sinus Endoscopic 19

8 F 32 None Nasal obstruction (2) 3.5 x 2.5 L Inferior turbinate Endoscopic 12

fiber.

Schwannoma has a well-developed capsule, and there is almost no instance of changing into a malignant tumor.

As schwannoma occurs in myelinated nerves, it does not occurs in optical nerve and olfactory nerve.

Most of schwannomas in head and neck lesion are acous- tic neuroma originating from the eighth cranial nerve, and schwannomas of the sinonasal tract are very rare.

There has been many case reports of sinonasal schwan- nomas and they are summarized in Table 2. Forty-seven cases of sinonasal schwannomas were found and available clinical data were collected. Each data are listed according to the frequency. In consistent with the results of this study, there was no sexual difference and most of the schwanno- mas were occurred between the age of third decades and sixth decades. Most common clinical symptom was nasal obstruction and headache, epistaxis, proptosis and facial

numbness in decreasing order. The most common origin site was nasal septum and this result is somewhat different from previous reports. In some reports, most commonly involved site of the sinonasal schwannoma was ethmoid sinus and nasal septum was not commonly involved.

These differences might arise from the difference between involvement and origin. However, considering the differ- ence, discordance exists. Most of the schwannomas were removed via endoscopic approach and there was no recur- rence.

Clinically, these tumors usually present like other benign nasal masses. Specific signs and symptoms depend on the size and location of tumor, and are due to involvement or pressure on surrounding structures.

If the tumor involves nasal cavity, symptoms such as unilateral nasal obstruc- tion, nasal discharge, or nasal bleeding may occur,

and if it makes an orbital or intracranial infiltration, symptoms including exophthalmos, diplopia, keratitis, and meningi- tis symptoms may occur.

As most of the schwannomas occured in nasal cavity, the most common symptom was nasal obstruction.

Radiologic studies are essential in sinonasal tumors.

Computed tomography of sinonasal schwannomas showed enhanced mass with nonenhance cystic lesion.

Computed tomography scans localize the disease but may not be helpful in distinguishing tumor from infection or inspissated secretions.

Magnetic resonance imaging of sinonasal schwannomas showed an intermediate signal intensity on T1-weighted images and intermediate (high cellular lesion) to high (cystic lesion) signal intensity in T2-weighted images.

Though these findings are not cru- cial in diagnosing sinonasal schwanommas, radiologic studies are mandatory for patients prior to surgery to plan the extent of surgical resection.

Histologically, schwannoma shows two different char- acteristic findings: Antoni type A and B. Antoni A is char- acterized by a spindle cell arranged well with surrounding connective tissues and Verocay body which is a region where populated nuclei is arranged in parallel. In con- trast, Antoni B shows degeneration with almost no spindle cells, which is sometimes accompanied by hemorrhagic necrosis.

S-100 protein is a specific marker in the neu- ral tissue. It appears positive in tumors originating from schwann cells or melanocytes.

In most cases, the nerve of origin for the schwannoma is not usually found. Typically, sinonasal schwannomas typically arise from the ophthalmic and maxillary branch- es of the trigeminal nerve, or from autonomic nerves in

Fig. 4. Representative histologic findings of sinonasal schwanno- mas show spindle-shaped cells arranged in bundles, sometimes resembling a palisade (A, H-E stain, x100). Immunohistochemi- cal study showed positive for S-100 (B, x100).

A B

A

D

G

B

E

H

C

F

I

Fig. 3. Magnetic resonance imaging of paranasal sinuses

showed an intermediate signal intensity on T1-weighted imag-

es (A, D, G), heterogeneously enhancing mass in T1-enhanced

images (B, E, H) and intermediate to high signal intensity in T2-

weighted images (C, F, I). Schwannomas are originated from

pterygopalatine fossa (A, B, C), nasal septum (D, E, F) and eth-

moid sinus (G, H, I).

and around the paranasal sinuses.

When the tumor arises from the nasal septum, it originates from sympathetic nerves to the septal blood vessels, parasympathetic nerves to septal mucous glands, and sensory nerves to the nasal septum.

Sinonasal schwanommas are usually removed without neurologic complication. However, in one report, a patient had postoperative anesthesia of the hard palate, likely due to resection of the greater palatine nerve in the pterygopalatine fossa.

Though it happens rarely, it should be considered according to the site of origin.

The principle for schwannoma treatment is surgical ex- cision. Radiation therapy is generally not indicated for these benign tumors. Completion resection of the lesion while preserving the neural function is recommended.

Schwannoma shows good progress just by surgical ex- cision alone, but some reports state follow-up is needed since there are approximately 10% of relapses or remain- ing tumors.

The surgical approach is determined accord- ing to the location and extent of the lesion. Our preference for excision of sinonasal schwannomas is via endoscopic approach. This approach offers the advantage of no ex- ternal incision, shorter hospital stay and lower morbidity when compared to traditional approaches.

In conclusion, schwannoma arising within the sinona- sal cavity is rare and shows unspecific clinical symptoms and radiological findings. It is considered that diagnosis through punch biopsy of the various locations of lesions along with Immunohistochemical staining will be impor- tant. Complete excision with endoscopic approach shows favorable outcomes with lower morbidity, and it is con- sidered as the treatment of choice for the sinonsal schwan- nomas.

Acknowledgments

This study was supported by a grant of the Korea Healthcare Tech- nology R&D Projects, Ministry for Health, Welfare & Family Af- fairs, Republic of Korea (A090084).

저자역할(Author Contributions)

홍성문, 신재민, 박일호, 이승훈, 김용대, 이흥만은 본 연구에서 모든 자료에 접근할 수 있으며, 자료의 완전성과 자료 분석의 정확성에 책 임을 지고 있습니다. 연구 기획 : 홍성문, 이흥만. 자료 해석 및 분석 : 홍성문, 신재민, 박일호, 이승훈, 김용대, 이흥만. 논문초안 : 홍성 문. 연구 총괄 : 이흥만.

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R: right, L: left

Table 2. Clinical findings of the sinonasal track schwannomas in the order of frequency: Review of the literatures.

Frequency Sex (n) Age (n) Symptom (n) Side (n) Site (n) Approach (n)

1 F (24) 30~39 (8) Nasal obstruction (17) L (14) Nasal septum (15) Endoscopic (26)

2 M (23) 50~59 (7) Headache (3) r (9) Ethmoid sinuse (8) Lateral rhinotomy (4)

3 - 40~49 (7) Epistaxis (3) - Pterygopalatine fossa (6) Bifrontal craniotomy (1)

4 - 20~29 (6) Proptosis (2) - Middle turbinate (3) Transpalatal (1)

5 - >60 (4) Facial numbness (1) - Nasal vestibule (3) Sublabial (1)

6 - 10~19 (2) Mass in vestibule (1) - lateral nasal wall (2) Caldwell-Luc (1)

7 - - - - Maxillary sinus (2) -

8 - - - - Inferior turbinate (1) -

9 - - - - Sphenoid sinus (1) -

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