Olfactory Nerve Schwannoma: A Case Report and Review of the Literature

Abstract

Schwannomas are benign tumors, which arise from the Schwann cells of the central or peripheral nerves. They form 8% of all intracranial tumors and most of the cases arise from vestibular division of the 8 th cranial nerve. Rare cases are shown to arise from the olfactory or optic nerve, being devoid of myelin sheath. Up to date and according to our best of knowledge, 66 cases have been reported till now. Here we present a review of the literature and a case report of a 56-year-old male with an accidently discovered anterior cranial fossa schwannoma, following a road traffic accident. Tumor was completely excised, using a right frontal approach. Histopathology revealed Antoni-A cellular pattern. Although rare, but olfactory nerve schwannomas should be included in the differential diagnosis in anterior cranial fossa space occupying lesions, and the approach should be designed taking into consideration, this rare entity.

Olfactory Groove Schwannoma or Olfactory Ensheathing cell Tumor?

“…Intracranial schwannoma can arise from any cranial nerve containing Schwann cells 4 . OGSs are extremely rare as the olfactory bulb and tract themselves are considered to lack Schwann cells 4,5 . The origin of OGSs remains a considerable debate.…”

“…When considering the differential diagnosis for OGSs, an olfactory groove meningioma should be the first choice 14–16 . The differential diagnosis also included glioma, neuroblastoma, metastatic, and abcess 5,17,18 . There have been some literature that summarized the differential diagnosis of OGSs 14,15 .…”

Endoscopic Endonasal Resection of a Schwannoma of the Anterior Cranial Fossa

“…Schwannomas of the anterior cranial fossa (ACF) are extremely rare: To the best of our knowledge, only 68 cases, including this one, had been reported in the literature 1,2 . Symptoms depend on the localization of the mass 3 : In this case, anosmia and nasal obstruction were determined by the nasal fossa extension.…”

“…Histopathological differential diagnoses include esthesioneuroblastomas, papillomas, meningiomas, nasopharyngeal carcinomas, and sarcomas 8 . The most common therapeutic choice reported is the resection via a subfrontal approach 1,9 . Although it is considered very conservative 10,11 , an endoscopic transnasal removal is not always viable and has been used only in a limited amount of cases [12][13][14] ; when the mass shows intranasal expansion, an endonasal approach could be considered for the exeresis.…”

Unusual Sites for Extracranial Head–Neck Schwannomas

“…Although any of the cranial nerves can be involved, rarely from optic and olfactory nerve for lack of myelin sheath, by far the most common involved cranial nerve is CN VIII [6]. They usually present initially as an asymptomatic slow growing solitary masses.…”