Nasal Cavity Schwannoma—A Case Report and Review of the Literature

Introduction

Schwannomas are rare slow-growing benign tumors that arise from Schwann cells, which form the myelin sheath of nerve fibers. Most of them occur in middle-aged adults, with equal gender and race distribution. Such tumors could be found throughout the whole body, and tumors in the head and neck region account for 25% to 45% of the cases. Schwannomas arising from the nasal cavity and paranasal sinuses comprised about 4% of all head and neck cases. ^1,2

The clinical symptoms of sinonasal schwannomas include nasal obstruction, epistaxis, rhinorrhea, anosmia, headache, facial swelling, and others. ³ Complete resection is the treatment of choice, and histology remains the gold standard for its diagnosis. Immunostaining for S-100 protein is helpful to distinguish schwannomas from inflammatory polyps, inverted papilloma, and other disease entities. ⁴ Recurrence after surgery is rare. In this study, we described a case of nasal cavity schwannoma, and literature was reviewed to summarize the information about its symptoms, origin, diagnosis, and surgical approaches, which are believed to be of educational importance.

Case Report

A 55-year-old female denied other systemic diseases or use of medications, except for a history of hysterectomy for uterine myoma. She had right-sided rhinorrhea for 4 months and intermittent epistaxis from the right nasal cavity for 2 months before her visit to the ENT department of a local hospital. A nasal polyp was impressed and surgical intervention was suggested. Then, she visited our outpatient clinic for a second opinion. On physical examination, a smooth-surfaced mass located at the right anterior nasal cavity abutting both the nasal septum and lateral wall was noted (Figure 1). The computed tomography (CT) scan, which was performed in a local hospital, showed a single mass measuring about 2.2 × 1.8 × 1.1 cm in size, occupying the anterior nasal cavity and without any evidence of sinusitis (Figure 2). Under the impression of a possible nasal cavity tumor, a biopsy was done after securing informed consent. Pathological examination revealed a schwannoma. Endoscopic surgery was done, and during the operation, the tumor was found to have a stalk anchored to the lateral nasal wall anterior to the middle turbinate. Grossly, the mass was yellowish, encapsulated, and 2.5 × 2.1 × 1.1 cm in size (Figure 3). Histologic examination revealed spindle tumor cells arranged in parallel and streaming patterns (Figure 4A), which were composed of Antoni A and Antoni B areas. Cytological atypia, mitosis, or necrosis were not identified. Immunohistochemically, the spindle cells were positive for S-100 (Figure 4B) and SOX10 and negative for CK AE1/AE3, CD34, SMA, and beta-catenin immunostaining. Postoperatively, her symptoms subsided and no evidence of recurrence was observed.

OPEN IN VIEWER

Figure 1.

A polypoid mass in the right nasal cavity abutting the lateral nasal wall and septum.

OPEN IN VIEWER

Figure 2.

Computed tomography scan: a mildly enhanced, homogeneous, soft tissue mass over the right common meatus, causing a partial obstruction and pushing the nasal septum to the contralateral side.

OPEN IN VIEWER

Figure 3.

A yellowish, encapsulated tumor, 2.5 × 2.1 × 1.1 cm in size.

OPEN IN VIEWER

Figure 4.

A, Spindle tumor cells arranged in parallel and streaming patterns with a focal palisading structure. B, Strong immunoreactive stain of S-100 protein.

Discussion

Schwannoma was first described by Verocay in 1910. It is a tumor that originates from the neuroectodermal Schwann cells of the cranial, peripheral, or autonomic sheaths. ⁵ Head and neck schwannomas could arise from multiple sites and account for 25% to 45% of all cases. Depending on the location, it is divided into nonvestibular, extracranial head and neck schwannomas and less commonly, intracranial acoustic schwannomas. ⁶ Sinonasal schwannomas are rare and account only for 4% of all head and neck schwannomas. ⁷ In line with these reports, Habesoglu et al reported that unilateral nasal symptoms could be attributed to neoplastic diseases (20.6%), inflammatory diseases (68.3%), and anatomic variations (11.1%). Among neoplastic diseases, inverted papilloma (6.3%) was the most common pathologic diagnosis. Schwannoma, ameloblastoma, pleomorphic adenoma, non-Hodgkin lymphoma, and squamous cell carcinoma were the least common findings (1.6%). ⁸

The origin of nasal schwannomas is hard to determine because of the thin nerve innervation over the nasal cavity. Its nerve attachment is difficult to identify during surgery. Sympathetic, parasympathetic, or sensory nerves are considered as their possible origin. ^9,10 Sympathetic nerves come out from the stellate ganglion and are distributed around the septal blood vessels. Parasympathetic nerves from the sphenopalatine ganglion innervate the septal mucous gland. The sensory nerves in the nasal septum originate from the branches of the ophthalmic nerve (anterior ethmoid nerve) and maxillary nerves (nasopalatine nerve). ¹¹ Olfactory groove schwannomas might arise from the olfactory bulb and nerve. ¹²

To understand nasal schwannomas better, a search in PubMed/Medline was conducted with the following terms: “nasal cavity” or “nasal septum” or “septal” or “nasal vestibule” or “nasal lateral wall” or “turbinate” and “schwannoma.” The query yielded 259 results. Of the 259 articles, those with unclear tumor origination or with tumors that did not originate from the nasal cavities and those not published in English were excluded. The search yielded 52 studies and a total of 71 patients, including this reported case. ^{1,2,7,9 -11,13 -58}

Of the 71 patients, 38 were males and 33 were females. Their age ranged from 5 to 82 years old, with a mean age of 44.62 ± 18.08 years. The greatest incidence of this disease was found in 40- to 60-year-old people, with no sex or racial predilection. ⁵⁰ The clinical symptoms of nasal schwannomas are very similar to those of inflammatory sinonasal diseases. Nasal obstruction was the main symptom mentioned by patients. In our review, the most common symptoms of nasal cavity schwannomas are nasal obstruction (92.4%), epistaxis (30.3%), and rhinorrhea (18.1%). Other symptoms, such as headache, hyposmia, nasal swelling and pain, exophthalmos, diplopia, or facial distortion, were less recorded (Table 1). These less reported symptoms usually implied more extended lesions with adjacent structure involvement.

OPEN IN VIEWER

Table 1.

Symptoms of Nasal Cavity Schwannomas.^a

Symptoms	Case numberb (%)
Nasal obstruction	61 (92.4)
Epistaxis	20 (30.3)
Rhinorrhea	12 (18.1)
Headache	10 (15.1)
Hyposmia	4 (6.1)
Facial pain	1 (1.5)
Nasal swelling and pain	3 (4.5)
Exophthalmos	2 (3.0)
Diplopia	1 (1.5)
Facial distortion	1 (1.5)
Asymptomatic	2 (3.0)

^a Sixty-six of the total 71 patients had recorded symptoms.

^b Some of the patients had more than one symptom.

For nasal cavity schwannomas, a high-resolution CT scan provides details about the size and extent of tumors. The tumors show mild and patchy enhancement pattern on contrast-enhanced CT scan. ⁵⁹ Magnetic resonance imaging is superior to CT in differentiating tumors from inflammatory changes and in the evaluation of their extranasal extensions. Magnetic resonance imaging signals show an intermediate signal intensity on T1-weighted images and a variation from intermediate intensity (highly cellular lesion) to heterogeneous high intensity (cystic and stromal lesions) on T2-weighted images. ²⁰ Preoperative images could help in the diagnosis and selection of the proper surgical approach.

It is hard to determine the tumor origin purely by images because of the total obstruction of the meatus or multiple sinus involvement. Thus, it is often identified during the operation, as seen in this case. In our review, 56 of the total 71 patients had recorded sites of origin, with the nasal septum (57.1%) being the most common site, followed by the lateral nasal wall (10.7%) and middle turbinate (10.7%). The other sites were the vestibule (7.1%), inferior turbinate (7.1%), and middle meatus (7.1%; Table 2).

OPEN IN VIEWER

Table 2.

Origins of Nasal Schwannomas.^a

Subsites	Case number (%)
Septum	32 (57.1)
Lateral wall	6 (10.7)
Middle turbinate	6 (10.7)
Vestibule	4 (7.1)
Inferior turbinate	4 (7.1)
Middle meatus	4 (7.1)

^a Fifty-six patients had recorded subsites of origin.

Histology is still the gold standard for its diagnosis because of its atypical clinical symptoms and lack of specific image manifestation. Microscopically, schwannomas present with 2 distinct patterns. Antoni A area has dense spindle cells with a palisading nucleus surrounding an acellular central lesion, referred to as Verocay bodies. On the other hand, Antoni B area shows a loose tissue composed of polymorphic cells separated by an abundant myxoid matrix. ^27,60 Immunohistochemical stains are often employed due to the difficulty in diagnosing it purely based on its morphology. Being positive for the S-100 protein can aid in the diagnosis. Although both schwannomas and neurofibromas are immunoreactive with the S-100 protein, Min and Kim reported that S-100 protein immunostaining was more intense on schwannomas than on neurofibromas. Moreover, Calretinin and CD56 are also highly specific for schwannomas, while CD34 and factor XIIIa are more sensitive for neurofibromas. ⁶¹ These markers further assist the differential diagnosis. Our case had an intense immunostaining for S-100 protein and negative for CD34, leading to the diagnosis of schwannoma.

The treatment for nasal cavity schwannomas is complete surgical excision. Head and neck schwannomas are usually encapsulated; however, some sinonasal schwannomas are not capsulated, making en bloc tumor resection difficult. ^2,62 The surgical procedure depends on the tumor size, location, and invasion of adjacent structures. The intervention for limited nasal cavity schwannomas usually involves transnasal excision with or without endoscopy. Open surgery is usually reserved for more extensive diseases. Endoscopic surgery has been mostly reported in the recent 20 years, and it is becoming the most widely used procedure. Even in extensive diseases, no recurrence was reported after endoscopic surgery. ^36,47,62 In our review, endoscopic surgery was done in most cases (52.1%). Some small anterior tumors were excised with a safe margin without endoscopy. For extensive diseases, open surgery is indicated, which often requires developing and elevating a local flap for a better surgical view. The reported open approaches include lateral rhinotomy, rhinoplasty, Caldwell-Luc or Denker’s operation, transpalatal incision, gingivobuccal incision, or midfacial degloving (Table 3). The recurrence rate of schwannomas after a complete surgery is very low. Forer et al reported 10 endoscopic resections of sinonasal tract schwannomas, and all the 10 patients remained disease-free after a mean follow-up of 65.3 months. ⁴⁶ This current review showed that the 59 patients with traceable records had no recurrence after a follow-up time of 3.58 ± 3.14 years after the surgical intervention.

OPEN IN VIEWER

Table 3.

Surgical Procedures for Nasal Cavity Schwannomas.^a

Surgical procedure	Number of cases (%)	Recurrence
Transnasal approach	41 (57.7)
Endoscopic surgery	37 (52.1)	No
Without endoscopy	4 (5.6)	No
Open approach	19 (26.7)
Lateral rhinotomy	8 (11.3)	No
Degloving or gingivobuccal incision	5 (7.0)	No
Caldwell-Luc or Denker’s operation	2 (2.8)	No
Transpalate approach	2 (2.8)	No
Rhinoplasty approach	1 (1.4)	No
Frontal craniotomy	1 (1.4)	No
Othersb	11 (15.5)	No

^a A total of 71 patients had a recorded operation.

^b No specific procedure described in the articles.

Nasal cavity schwannomas are benign tumors, with nasal obstruction, rhinorrhea, and epistaxis as the most common symptoms. It could be managed by either transnasal resection or open surgeries. The evidence suggests that even in advanced diseases, endoscopic surgery could provide a recurrence-free resection.