Carcinoma of the breast metastatic to the optic nerve mimicking an optic nerve sheath meningioma: case report and review of the literature.

Isolated metastatic tumors to the optic nerve are extremely rare. We describe a rare and unusual case of metastatic breast carcinoma to the optic nerve that mimicked an optic nerve sheath meningioma in its presentation due to its indolent symptom progression, initial radiological appearance, and minimal growth on serial imaging. The patient, a 46-year-old woman with a history of stable metastatic breast carcinoma, presented with progressive visual loss in her right eye over a 6-month interval. Magnetic resonance imaging revealed an enhancing lesion in the optic canal with an extension to the right anterior clinoid process and planum sphenoidale and into the right orbital apex, consistent with the presumptive diagnosis of optic nerve sheath meningioma. The tumor was resected and pathologically confirmed to be metastatic carcinoma of the breast. The clinical course, radiological features, surgical approach, and treatment strategies are reviewed.