Ancient Olfactory Schwannoma - Case Report and Literature Review.

Intracranial schwannomas are benign tumors that arise from Schwann cells. Since it is well known that optic and olfactory nerves do not have a Schwann cell sheath, schwannoma should not develop from these nerves. We report a very unusual case of a 73-year-old female who presented with generalized seizures and had radiological features of an intracranial aneurysm. Additional imaging showed an extracerebral mass 2.5 x 2.0 cm in size, which most likely corresponded to a meningioma. It was resected in total. Subsequent histological analysis revealed that the tumor was in fact ancient schwannoma WHO grade I. Only about 41 case of olfactory schwannoma have been reported in the literature. Olfactory groove schwannomas are extremely rare tumors, occurring less frequently than any other intracranial nerve schwannoma. As in this case, the schwannoma should be included in the differential diagnosis of the anterior cranial fossa tumor. Further research on the pathogenesis and the origin of olfactory groove schwannoma is needed.