3. Discussion
Schwannomas are benign slow-growing masses with a less destructive pattern (5). Obstruction of the nasal cavity is the most common clinical presentation in nasal cavity schwannoma, although other less common symptoms include visual disorders, facial nerve palsy, facial pain, and exophthalmos(6). In the head and neck region, neck soft tissue, parapharyngeal space, and oropharynx are the most commonly diagnosed locations. Hence, schwannomas limited to the nasal cavity are extremely rare, with approximately 20 reported cases in the literature. (7) In most reports, the nasal cavity schwannoma originated from the nasal septum (6-9), and only in one case, the tumor origin was reported to be from the nasal sidewall.
This disorder usually occurs in the fifth and sixth decades of life and issues related to sex and race do not play a significant role in its occurrence (10). It has been reported that nasal cavity schwannomas originate from the maxillary and ophthalmic nerves, sphenopalatine ganglion, and other nerves that innervated the nasal mucosa (8). In the present patient, nasal cavity schwannoma originated from the lateral nasal wall, and given that the lateral wall is innervated by anterior ethmoidal nerve, lateral posterior inferior nasal, and lateral posterior superior nasal, it seems that aforementioned schwannoma is associated with above nerve, however, due to the complex pathomechanism of schwannoma, it is not possible to make a definite statement about the origin of this type of schwannoma and the issue is open to As previously mentioned, the pathomechanism of schwannoma is very complex and several factors are involved in its development. It has been suggested that oxidative stress plays a crucial role in the pathogenesis of schwannoma(11). Based on the review of literature, in some cases of nasal schwannoma, the patient had diabetes mellitus (8). In our study, the patient had diabetes for 4 years. Although diabetes mellitus increases free radicals through lipotoxicity and glucotoxicity(12), we cannot say certainty that diabetes has been one of the risk factors for schwannoma in our patients, and this requires precise cellular and molecular studies. Differential diagnosis between different tumors of the nasal cavity such as squamous cell carcinoma, schwannoma, lymphoma, fibrous dysplasia, chondrosarcoma, and extension of the angiofibroma of the nasopharynx is very difficult based on clinical findings. As we know, medical imaging such as CT scans may not provide valuable findings for differential diagnosis, but they are useful in evaluating the size, diameter, and extent of mass (13). The most accurate method for the definitive diagnosis of schwannoma is histopathological assays. Schwannomas generally have a smooth appearance and are covered by a capsule derived from the perineurium of the nerve. Also, these tumors grow eccentrically to the nerve from which they arise. Another diagnostic criterion is the presence of spindle cells with a basophilic histological pattern. In the present study, the pathology report described a benign spindle cell neoplasm that was Compatible with schwannoma(5). In macroscopic view, schwannoma is lonely, well-demarcated with a round or oval shape, yellowish to grayish in color, and shiny on cut surface (6). In our study, the macroscopic appearance of the mass was in accordance with Schwannoma criteria, but as mentioned, it has no high diagnostic value (Fig 2). According to the nature of schwannoma, excision by external approach or endonasal surgery is the treatment of choice based on tumor size and extension. (14) With this in mind, in our case due to the tumor size and its limited extension, the endonasal approach was selected.