Bilateral Infiltrative Optic Neuritis as the Presenting Finding in Metastatic Gastric Leptomeningeal Carcinomatosis

Background: To present a rare case of leptomeningeal carcinomatous (LMC) secondary to previously undiagnosed metastatic gastric adenocarcinoma with infiltrative optic neuritis as a presenting finding. Case Presentation: A 58-year-old female with no known cancer history presented with 3 months of blurry vision, headaches, and paresthesias. Exam showed bilateral optic disc edema with peripapillary hemorrhages and white infiltrates. Cerebral spinal fluid cytology revealed malignant cells and oncologic workup revealed metastatic gastric adenocarcinoma with signet-ring cells. The patient was treated with systemic chemotherapy. She had a significant improvement in her infiltrative optic neuropathy, both clinically and radiographically, in response to systemic chemotherapy alone. Intrathecal (IT) chemotherapy is often used in the treatment of LMC but was deferred due to the patient’s dramatic improvement with systemic therapy alone. Conclusions Bilateral optic disc edema has a broad differential. This case highlights the importance of keeping LMC in mind, even in the absence of a known cancer history. Though IT chemotherapy is often used in treatment, a remarkable response can be seen with chemotherapy alone and management should ultimately be tailored to the individual.