Intracranial schwannoma presenting as a subfrontal tumor: case report.

OBJECTIVE AND IMPORTANCE Intracerebral schwannomas not associated with cranial nerves account for less than 1% of surgically treated schwannomas of the central and peripheral nervous system. Subfrontal schwannomas are extremely rare, with only 15 cases reported to date. CLINICAL PRESENTATION A 33-year-old man presented with a 4-month history of progressive headaches and lethargy. Radiographic studies revealed a large subfrontal tumor thought to be a meningioma preoperatively. INTERVENTION The patient underwent a craniotomy for resection of his tumor. Intraoperatively, a large extra-axial tumor arising from the floor of the left frontal fossa was encountered. CONCLUSION Microscopic examination of the tumor revealed a schwannoma. Several theories on the possible origin of intracerebral schwannomas have been considered. Because of the age of the patient at presentation, many authors have postulated a developmental origin for these lesions. However, extra-axial schwannomas not associated with cranial nerves often present later in life, suggesting a different pathogenesis for this subgroup.