Leptomeningeal Carcinomatosis: A Case Report of Metastatic Triple-negative Breast Adenocarcinoma

A 55-year-old female presented to the emergency department with seizures, left hemiparesis, and memory loss. Her past medical history was notable for a right triple-negative breast adenocarcinoma that was diagnosed approximately two years prior. She underwent treatment with chemotherapy, right breast lumpectomy, and radiation near her rural hometown. Radiologic studies were performed in the emergency department. Brain imaging revealed a new 2-cm mass in the left breast and a 4-cm left frontal lobe brain lesion. She underwent an urgent craniotomy. Immunohistochemical staining of the brain tumor tissue suggested metastatic triple-negative breast adenocarcinoma. She was discharged with recommendations to follow up with her prior oncologist near her home for systemic chemotherapy. Three months after metastatic breast cancer to the brain was diagnosed, the patient experienced headaches, fever, and nuchal rigidity. MRI of the brain showed new leptomeningeal enhancement. A lumbar puncture with a cerebrospinal fluid analysis revealed the presence of malignant cells. Together with imaging and cerebrospinal fluid findings, leptomeningeal carcinomatosis was diagnosed. This case report presents an uncommon but well-known complication of breast cancer.