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SCHWANNOMA OF THE NOSE

Nishit J Shah*, Priti P Jain**, Sunil Budhlani**
*Honorary Associate Consultant in ENT; **Senior Resident; Bombay Hospital and Medical Research Centre,
Mumbai - 400 020.

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Neuroplasms of Schwann cell origin occur only rarely in the nasal cavity, paranasal sinus and nasopharynx. Schwannomas have also been termed as neuromas, neurinomas, neurofibromas, perineural fibroblastomas and perineural fibromas. Schwannomas are slow growing, but they can become very large, expanding and eroding bone by pressure[7] Common symptoms include nasal obstruction, epistaxis, rhinorrhoea, anosmia, facial swelling, headache and facial pain. Magnetic resonance imaging and CT scanning are invaluable diagnostic tools to demonstrate and assess tumours of the nose and nasopharynx. Microscopic sections show the typical elongated or spindle shaped cell with an oval or flattened nucleus, usually with a palisading effect. For most cases lateral rhinotomy affords the best access to the nasal cavity and paranasal sinus.

INTRODUCTION

Schwannomas are very rare in the nose and paranasal sinus[1, 2] They arise most commonly in the ethmoid and maxillary sinuses with two cases having been reported in the sphenoid sinus. There are no reported cases of frontal sinus schwannomas. [3] Schwannomas have also been termed as neuromas, neurinomas, neurofibromas, perineural fibroblastomas and perineural fibromas. [4] Schwannomas have attributed to arise from the sheath of Schwann, in which case they would be of ectodermal origin. If multiple tumours originate from the cutaneous, visceral, and cranial nerves, the condition is known as von Recklinghausen’s disease, which as a rule does not involve the nose or throat. [4]

Tumours are discovered late in the clinical course because of their obscure anatomic location and late onset of symptoms. [5]

CASE REPORT

A 23 year old patient presented with complaints of nasal obstruction on both sides and rhinorrhoea since two years. Patient also complained of frontal headache and periorbital pain with external nasal deformity and shift of right eye ball laterally. No history of epistaxis, diplopia or epiphora was given. Patient had a history of trauma to the nose two years back. On examination, an external bulge was present on the right side of the nose with deviation of the right eyeball laterally. On anterior rhinoscopy, a reddish mass filling the whole right nasal cavity was seen pushing the septum to the opposite side. The mass was firm, non-tender, did not bleed on touch and was not freely mobile. CT scan revealed a large mass occupying the right nasal cavity, the right ethmoid sinuses and extending to the choana. The nasopharynx was free of tumour. Routine haematological investigations and X-ray chest were normal and the patient was posted for surgery and complete excision of the mass achieved by the lateral rhinotomy approach. The histopathology report was schwannoma of the nasal cavity. The section showed polypoidal strips of inflamed nasal mucosa and large portions of benign nerve sheath tumour characterised by Antoni A and Antoni B areas. Nuclear palisading is noted with engorged vessels within the tumour. Follow up after two months showed no recurrence in the nose or any other complaints.

Fig. 1 : CT scan of paranasal sinuses (axial section) showing tumour in the nose and the ethmoid sinus.	Fig.2 : CT scan of paranasal sinuses (coronal section) showing schwannoma in the nose and the ethmoid sinus.

DISCUSSION

Only 4% of head and neck nerve sheet tumours involve the paranasal sinus. Benign schwannomas are the commonest type with less than 40 cases occurring within the paranasal sinus. [6] Schwannomas are slow growing, but they can become very large, expanding and eroding bone by pressure. [7] Common symptoms include nasal obstruction, epistaxis, rhinorrhoea, anosmia, facial swelling, headache and serous otitis media. Lesions involving the paranasal sinus often lead to pain in the facial or orbital area. Schwannomas can show local bony destruction with possible intracranial extension, including visual disturbances. [2,8].

Neurinomas involving the nose, throat or larynx are usually solitary lesions and on examination they present as localized masses in the nasal cavity. [4] Nasal endoscopy may add further information to the examination findings and arouse suspicion of a nerve tumour. [9]

Magnetic resonance imaging and CT scanning are invaluable diagnostic tools to demonstrate and assess tumours of the nose and nasopharynx. Radiology is invaluable for preoperative planning of excision.

In addition, biopsy can confirm the diagnosis. However, brisk bleeding may occur at biopsy or removal due to the rich vascular stroma. [7] Benign Schwannomas usually consist of solitary, encapsulate masses that are attached to an adjacent nerve, from which the lesions presumably arose. Microscopic sections show the typical elongated or spindle shaped cell with an oval or flattened nucleus, usually with a palisading effect. In some areas, these neoplasms exhibit moderate to marked cellularity (Antoni A areas), here nuclear palisading usually is found. Myxoid or degenerative changes usually are seen in less cellular areas (Antoni B). These tumours are composed of cytologically benign appearing cells that have the typical feature of Schwann cells.[2,4] Apart from the olfactory nerve, any of the nerves supplying the nose and paranasal sinus may give rise to the tumour, somatic or autonomic. It is however, unusual to identify the particular nerve of origin. [6] An unusual feature was a lack of encapsulation which when combined with hypercellularity often raised suspicion of malignancy. [8] Recently malignant change in a long standing benign schwannoma has been reported. [6,10] Malignant schwannoma arising in a paranasal sinus is quite a rare clinical entity. [11] A search of the literature revealed only 11 previously reported cases. Immunohistochemistry with S-100, antiglial fibrillary acidic protein (GFAP), vimetin and cytl cavitokeratin are employed to confirm malignant schwannoma, and differentiate it from other tumours. [8,11,12] Fibroma, fibrosarcoma, and leiomyoma may cause diagnostic confusion. [7]

For most cases, lateral rhinotomy affords the best access to the nasal cavity and paranasal sinus. Alternative procedures include a Caldwell - Luc approach for maxillary sinus lesions with the addition of external ethmoidectomy if involvement has occurred. Skull based surgery may be necessary for sphenoidal schwannomas. More advanced lesions or any tumour extending through the cribriform plate are more safely tackled via acreotomy, combined with any of the other approaches. [6] For benign schwannomas, gross total excision is curative, but subtotal excision is reasonable when cranial nerve function must be spared. Tumours that present little risk for serious complication may be appropriately left alone. [7] Occasionally tumours appear to be encapsulated but may have invasive tendencies and can recur after removal. [4,13]

Malignant schwannomas can be treated by surgical excision, external RT, and Radon seed implants. [9] It is important to have a regular follow up of all operated patients to detect any recurrence if it does occur.

ACKNOWLEDGEMENT

We would like to thank the Dean, Dr. BK Goyal for allowing us to publish hospital data. We would also like to thank Ms. Clasy Cardoz for her help in preparing the manuscript.

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