Subfrontal Schwannoma Extended Broadly to Nasal Cavity Treated by Gamma Knife Radiosurgery Following Surgical Excision: A Case Report.

Subfrontal schwannomas are rarely reported. They are usually found only in the subfrontal area, but some extend to the nasal cavity. In these cases, prevention of postoperative cerebrospinal fluid (CSF) leakage through thinned or eroded anterior skull base is important. A 51-year-old female with anosmia and mild nausea was diagnosed as subfrontal extraaxial mass with nasal cavity extension. This mass was initially thought to be an olfactory groove meningioma. We performed a bifrontal craniotomy for surgical excision. We did not totally remove the tumor, as we wanted to prevent a skull base defect. The histopathological diagnosis was a schwannoma. There was no postoperative complication such as CSF leakage. The residual tumor was treated with gamma knife radiosurgery. The nasal cavity mass has not grown as of five years after radiosurgery.