[Intranasal extradural meningiomas. Case report and review of the literature].

Report on an extradural meningioma of the left nasal cavity and ethmoid sinus with secondary extension into the subfrontal region in an 18-year old male. Review of 37 similar cases reported in literature. These slowly growing non-infiltrating tumours cause nasal obstruction and sinusitis but have no characteristical clinical symptoms. The origins of these tumours are obviously arachnoideal meningocytes which accompany the olfactory filaments through the lamina cribrosa to the extradural site.