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|LETTER TO EDITOR
|Year : 2014 | Volume
| Issue : 1 | Page : 96-98
Schwannoma of supraorbital nerve presenting as a subfrontal tumor
Ari George Chacko1, Manikandan S Natarajan1, Krishna Prabhu1, Geeta Chacko2
1 Department of Neurological Sciences, Christian Medical College, Vellore, Tamil Nadu, India
2 Department of Neuropathology, Christian Medical College, Vellore, Tamil Nadu, India
|Date of Submission||08-Jan-2014|
|Date of Decision||08-Jan-2014|
|Date of Acceptance||31-Jan-2014|
|Date of Web Publication||7-Mar-2014|
Department of Neurological Sciences, Christian Medical College, Vellore, Tamil Nadu
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Chacko AG, Natarajan MS, Prabhu K, Chacko G. Schwannoma of supraorbital nerve presenting as a subfrontal tumor. Neurol India 2014;62:96-8
Schwannomas in the naso-ethmoidal region are uncommon and approximately 40 cases are reported in literature, 8 of which with intracranial extension.  Though these commonly arise from naso-ethmoidal region, tumors arising from the frontal sinus has not been reported,  hence this report.
A 66-year-old female patient presented with progressive proptosis of the left eye and decreased smell on the left side for 6 months. The visual acuity was 6/9 in both eyes with non-axial proptosis, ptosis and restricted up gaze in the left eye. Magnetic resonance imaging (MRI) and computed tomography (CT) [Figure 1]a and b showed an extra-axial mass in the left frontal region with soft-tissue attenuation, heterogeneous and hyperintense on T2-weighted images with heterogeneous but intense gadolinium enhancement. The mass filled and expanded the frontal sinus. Inferiorly, the mass extended through the cribriform plate and frontal sinus duct into the nasal cavity on both sides of the midline. The preoperative differential diagnosis were esthesioneuroblastoma, meningioma, hemangiopericytoma, papilloma, adenocarcinoma, lymphoma and fungal granuloma. At surgery the tumor was found to have expanded the frontal sinus but had eroded the superior orbital rim in the region of supraorbital foramen. Histopathology was suggestive of schwannoma [Figure 1]c. A 12-month follow-up CT scan showed no tumor [Figure 1]d.
|Figure 1: (a) Pre-operative magnetic resonance imaging coronal with gadolinium showing a contrast enhancing heterogeneous mass, expanding and distorting the frontal sinuses and extending through the cribriform plate into the nasal cavity. (b) Pre-operative computed tomography (CT) coronal showing the bony changes and breach of the cribriform plate. (c) Photomicrograph of schwannoma illustrating interlacing fascicle of spindle shaped cells (H and E, ×90). (d) Follow-up CT after 12 months showing no tumor|
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About 25-45% of schwannomas arise from the head and neck region, a naso-ethmoidal region being the most common followed by the maxillary sinus, nasal cavity and the sphenoid sinus.  The intranasal schwannomas may arise from any of the following nerves: (a) General sensory branches of the ophthalmic and maxillary divisions of the trigeminal nerve; (b) Autonomic fibers (parasympathetic) from the sphenopalatine ganglion and (c) Autonomic fibers (sympathetic) derived from the carotid plexus. Adachi et al.  classified Subfrontal schwannomas into two main types; schwannoma of the olfactory site (olfactory groove or cribriform plate) and others (which arise from non-olfactory sites).
It is likely that, in our case, the schwannoma arose from the supraorbital nerve that supplies the frontal sinus, completely filling that cavity resulting in proptosis by mechanical compression of the globe, anosmia due to the involvement of olfactory nerves on the left side and ptosis due to mechanical compression or involvement of the levator palpebrae superior is muscle. This benign slow growing tumor expands and thins confining bony cavities and widens the foramina of nerves from which it arises.  The differential diagnosis for spindle cell tumors in this location includes juvenile angiofibromas, solitary fibrous tumors, hemangiopericytomas, fibrosarcomas, synovial sarcoma and leiomyosarcomas.  Other lesions that can occur in this region are Esthesioneuroblastoma, squamous cell carcinoma, adenocarcinoma, meningioma, lymphoma and metastases.
In our case, the MRI defined the tumor within the frontal sinus and extending inferiorly along the course of the supraorbital nerve with no brain seen anterior to the tumor. This is in contrast to the naso-ethmoidal type of schwannoma where the tumor originates posteriorly in the naso-ethmoid region and finds its way intracranially through the cribriform plate resulting in a component of brain seen anterior to the tumor.  Establishment of the diagnosis of schwannoma versus neuroblastoma is important because it obviates the need for more aggressive craniofacial resection. 
| » References|| |
|1.||George KJ, Price R. Nasoethmoid schwannoma with intracranial extension. Case report and review of literature. Br J Neurosurg 2009;23:83-5. |
|2.||Schwartz TH, Bruce JN. Extended frontal approach with bilateral orbitofrontoethmoidal osteotomies for removal of a giant extracranial schwannoma in the nasopharynx, sphenoid sinus, and parapharyngeal space. Surg Neurol 2001;55:270-4. |
|3.||Adachi K, Yoshida K, Miwa T, Ikeda E, Kawase T. Olfactory schwannoma. Acta Neurochir (Wien) 2007;149:605-10. |
|4.||Yako K, Morita A, Ueki K, Kirino T. Subfrontal schwannoma. Acta Neurochir (Wien) 2005;147:655-7. |
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