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.