Symptoms of Isolated Optic Neuropathy in a Patient with Systemic, Brain, and Meningeal Metastases from Breast Cancer: A Case Report.

Introduction: Ocular metastases from breast cancer, particularly involving the optic nerve, are rare and pose a diagnostic challenge. Typically, optic nerve metastases are believed to originate from nearby choroidal metastases or hematogenous spread through the posterior ciliary arteries. However, there have been some reports of metastases through leptomeningeal dissemination. The aim of this report was to describe a case of multiple brain metastases from breast cancer without subjective symptoms other than central scotoma, which was diagnosed with repeated magnetic resonance imaging (MRI). Case Presentation: A 62-year-old woman who had previously undergone a mastectomy for left breast cancer complained of left ocular pain during eye movement and left visual loss. Initial contrast-enhanced MRI showed no significant abnormalities, and idiopathic optic neuritis was suspected. Despite steroid pulse therapy, her visual function did not improve. After four and a half months, her visual acuity worsened, and repeat contrast-enhanced MRI showed brain metastases involving the optic nerve sheath. Conclusion: Despite the multiple brain metastases, ultimately the patient's only symptom was unilateral visual loss. These findings highlight the usefulness of repeated contrast-enhanced MRI for detecting brain metastases, especially in cases without other apparent neurological symptoms or initial imaging abnormalities.