An Extensive Unilateral Nasal Mass: Septal Schwannoma—Case Report

Abstract

Schwannomas are benign peripheral nerve sheath tumours that arise from the Schwann cells of the myelinated nerve and may occur throughout the body. Paranasal schwannomas are uncommon lesions, representing less than 4% of all head and neck schwannomas and nasal septal schwannomas are very rare. Here we report a rare case of sinonasal schwannoma in a 46-year-old male who presented with a history of progressive nasal blockage of 3 years duration. The mass was removed by endoscopic approach without any postoperative complication. The rarity of diagnosis was aided by immune histopathology (IHC) of the tissue to confirm the disease.

Introduction

Schwannoma is benign nerve sheath tumour composed of Schwann cells. It was first described by Verocay in 1908 [1]. Stout (1935) gave the term neurilemmoma believing that these tumour arose from schwann cells of myelinated nerves [2]. Out of all schwannomas occuring in the body, 45% of them are from head and neck region. Out of those 45%, involvement of nose and pasanasal sinuses is only 4% [3, 4]. Diagnosis of nasal schwannoma depends upon histological findings because it has no characteristic radiological features [5]. Bogdasanian and Stout were the first to describe the case of neurilemmoma of nasal septum [6]. Here we describe a case of nasal septal schwannoma along with the review of the literature for this rare entity.

Case Details

A 46-year-old male presented with a history of progressive nasal obstruction initially of the right side which progressed to complete nasal obstruction in 3 years of duration. Other symptoms included mucoid rhinorrhoea, anosmia, change in voice, mouth breathing and occasionally associated with facial pain and frontal headache. No complains of blood stained nasal discharge, difficulty in vision or epiphora. No past history suggestive of tuberculosis, or any comorbidities. There was also no history of trauma, exposure to radiation or any nasal surgery. His family history was otherwise unremarkable.

Local examination and anterior rhinoscopy revealed fleshy nasal mass in the right nasal cavity pushing the septum towards the left side. Mass was found to be mildly sensitive and bled on touch. Endoscope was not negotiable in the nasal cavities. Mass was seen on posterior rhinoscopy with a bulge of the soft palate. Eye movement was complete however proptosis of right eye was present. Rest of the ENT examination was normal. Depending upon the clinical examination, clinical differential diagnosis of sinonasal neoplasm and inflammatory aetiology were suspected.

Patient was advised contrast enhanced computed tomography scan (CECT scan) of head and neck to look for any bony erosion. He was also advised magnetic resonance imaging (MRI) of nose and pasanasal sinuses to look for soft tissue extension and intra cranial involvement. Contrast enhanced CT scan and MRI nose and paranasal sinus revealed a non-enhancing, large soft tissue lesion in the (R) nasal cavity causing deviation of the septum to (L) with complete obliteration of contralateral nasal cavity. The lesion causing rarefaction of the septum with remodelling of the surrounding bones causing thinning and bowing of lamina papyracea into the (R) orbit causing proptosis. There was also the bowing of the medial wall of maxillary sinus into maxillary antrum, posteriorly into the nasopharynx causing complete obliteration of nasopharynx. The tumour also cause obliteration of all the sinuses with obstruction of the frontal drainage pathway. There was no intracranial extension (Fig. 1). All routine blood and urine examination results were normal. In view of the clinical picture and radiological imaging findings Sinonasal neoplasm was suspected. Patient was planned for biopsy.

Fig. 1.

a, b MRI T1 weighted images of nose and paranansal sinuses showing a large non enhancing soft tissue lesion completely obliterating the right nasal cavity and nasopharynx (white arrow) with no intracranial extension (yellow arrow). c CT Scan axial cut shows the thinning and bowing of bony septum (white arrow) and medial wall of maxillary sinus (yellow arrow) caused by the lesion

The patient was explained about his condition. He underwent punch biopsy of the lesion under local anaesthesia and specimen was sent for histopathological examination. The report of histopathological examination was suggestive of benign nerve sheath tumour-possibly schwannoma. After pre-anaesthetic check-up and informed consent of the patient, he was taken up for endoscopic resection of the lesion as endoscope will give good magnification during surgery with minimal morbidity and better cosmesis. The part of the lesion was removed piecemeal with cold steel instruments and sent for histopathological examination. The rest of the lesion was removed using microdebrider with care to identify the site of origin/attachment of lesion. It was a well circumscribed lesion arising from the postero superior part of bony septum and excised completely along with mucoperiostium. Bilateral nasal cavities were packed with medicated surgical sponge. Immediate post-operative phase was uneventful. Nasal pack was removed after 48 h and patient was advised for normal saline nasal douching. There was no post-operative complication.

On histopathological examination, the gross examination showed multiple tissue fragments of maximum size 3.5× 2 cm collectively, gelatinous mass with circumscribed margins. Microscopic examination showed spindle shaped cells arranged in short bundles and forming interlacing fascicles with nuclear palisading. Antony A and Antony B areas with verocay bodies (H and E; 10×). Further microscopic examination showed benign nerve sheath tumour—schwannoma. Immunohistochemistry revealed immune positivity for S100 and CD34 and focal positive for NSE thus confirming the diagnosis (10×) There was no capsular invasion. (Fig. 2).

Fig. 2.

H&E stain (a 40×) A biphasic pattern composed of hypercellular Antoni A areas (arrow) & myxoid hypocellular Antoni B areas (arrow head). Images (b 100×, c 200×) show nuclear palisading around fibrillary process (Verocay bodies) in cellular area (star) with elongated, narrow tumour cells having wavy with tapering ends, ill-defined cytoplasm and dense chromatin. Immunohistochemistry show positivity for NSE (d 100×), S-100 (e 100×) and very low KI67 of 1–2% (f 100×)

The patient was relieved of his symptoms and was under follow up for two years with complete remission (Fig. 3).

Fig. 3.

Pre and post-operative CT scan axial cuts showing complete clearance of the disease

Discussion

Unilateral tumours in nose causing obstruction, epistaxis and fullness are usually benign such as mucocele, polyps and cyst but some rare tumours like esthesioneuroblastoma, idiopathic midline granuloma, malignant neurilemmoma, olfactory grove meningioma, hemangiopericytoma and schwanomma should also be considered [7]. Schwannoma is a slow growing benign tumour arising from Schwann cells in the peripheral nerve sheath. Less common sites for schwannomas are scalp, face, oral cavity, and respiratory track. According to meta-analysis done by James Anderson Alloy et al. in 2014, in 94 patients of anterior skull base and sinonasal tract schwannoma, the age distribution is 14–81 years. Sinonasal schwannomas are very rare with most commonly arise from ophthalmic and maxillary division of trigeminal nerve and very rarely from sympathetic fibres of carotid plexus and parasympathetic fibres of pterygoplatine ganglion. Most common sinus involved is ethmoid sinus and nasal septum being the rarest [8]. Common presentation of nasal septal schwannoma is nasal obstruction, anosmia, facial swelling, pain, epistaxis or rhinorrhoea. Its malignant transformation is very rare [9].

Due to various possible pathology, it will be difficult to diagnose sinonasal schwannoma only on clinical bases using nasal endoscopy. Even radiological imaging is not helpful for diagnosing schwannoma but it is useful to see origin and extent of tumour. Preoperative biopsy is considered to diagnose these type of cases but excisional biopsy can also be done based upon clinical and radiological assessment [10]. Schwannomas appear as gelatinous, cystic, well circumscribed encapsulated masses and are usually amenable for endoscopic removal [11]. On histopathological examination, schwannomas exhibit Antoni A and Antoni B patterns. Hypercellular or Antony A areas contain spindle shaped cells arranged in interlacing fascicles. Hypocellular or Antony B areas contain the cells in a loose myxoid stroma with few spindle cells. Parallel rows of palisading nuclei also called verocay body can be seen in highly differentiated tissue [12]. Nasal schwannomas have little different histopathology at few areas as autonomic nerve fibres innervating nasal mucosa do not have perineural sheath so schwannomas from this area are noncapsulated [13]. So histopathology is gold standard for the diagnosis. Schwannomas usually show intense immunostaining for S-100 which helps to distinguish it from other tumours [14].

The treatment is complete endoscopic excision but depending upon the location and extent of lesion, sometimes lateral rhinotomy has to be done. Though recurrence is rare after removal, but long term follow up is required because there are reports of malignant changes in long standing benign schwannoma [14].

Conclusion

In conclusion, schwannoma arising from the nasal cavity are very rare and the correct diagnosis can be made by histopathological studies and IHC. The possibility of schwannomas should be considered when there is tissue mass in nasal cavity. Additionally, endoscopic endonasal approach being minimally invasive, is the ideal treatment, with improved visualization, lower morbidities, shorter hospital stays and external scar avoidance.

Declarations

Conflict of interest

The authors declare that they have no conflict of interest.