Meningioma: (1,2) A tumor of the optic nerve sheath can arise causing proptosis and visual loss. CT scan may reveal a thickened optic nerve with increased signal along the edges of the nerve resembling train tracks. A meningioma is a proliferation of meningothelial cells. Psammoma bodies are present in approximately 15% of specimens of optic nerve meningiomas as is seen on these slides. Back to Optic Nerve