Supratentorial extraparenchymal schwannoma mimicking parasagittal meningioma: A rare case report.

Background: Intracranial schwannomas not related to cranial nerves are very rare. Young age, no known history of neurofibromatosis, and seizure as initial symptom have been reported to be associated with intraparenchymal schwannoma.

Case Description: We report a case of supratentorial parasagittal schwannoma in the right frontal region presenting with seizure episode in a 70-year-old man. Computed tomography and magnetic resonance imaging showed a right frontal solid, enhancing extra-axial lesion based on anterior and middle third junction of superior sagittal sinus. The preoperative diagnosis was right parasagittal meningioma, however, the microscopic examination of the mass showed the characteristic pattern of cellular Antony A pattern. Immunohistocemically, the tumor stained positive for S-100 protein but negatively for epithelial membrane antigen and glial fibrillary acidic protein. These findings are consistent with schwannoma. Cysts, calcification, and peritumoral edema are common in intracerebral schwannoma, which were not seen in our case.

Conclusion: On the basis of clinical presentation and radiological appearances, schwannoma in unusual sites can easily be mistaken for meningiomas; immunochemistry plays an important role in differentiating them. Till date, to the best of our knowledge, this is the second reported case of schwannoma mimicking meningioma in parasagittal location.