Which is the most common intrinsic tumor of the optic nerve?

• A. Optic nerve glioma
• B. Astrocytoma
• C. Meningioma
• D. Rhabdomyosarcoma

Answer: (A)

Intrinsic tumors of the optic nerve arise from cells within the nerve itself, typically glial cells. The optic nerve glioma is the classic example of this, and it is the most common intrinsic tumor of the optic nerve, especially in children and often in people with NF1. These tumors grow along the nerve and produce vision loss and sometimes proptosis; imaging often shows enlargement of the optic nerve. Other listed tumors come from tissues surrounding the nerve or from other orbital structures rather than originating inside the nerve itself — for instance, meningioma arises from the surrounding meninges, rhabdomyosarcoma is a soft-tissue tumor, and astrocytoma can occur elsewhere in the CNS but the familiar, intrinsic optic nerve tumor is the optic nerve glioma. This combination of glial origin, localization inside the nerve, and pediatric predominance explains why it’s the best answer.