Asynchronous leptomeningeal carcinomatosis from pancreatic cancer: a case report and review of the literature.

Central nervous system (CNS) metastases from pancreatic cancer are an exceedingly rare occurrence and have been predominantly described as focal lesions within the brain parenchyma. Even fewer reports exist of tumor spread to the leptomeninges, and most cases are discovered at autopsy. No report of leptomeningeal carcinomatosis without brain parenchymal involvement has been described to date. We describe a 72-year-old female diagnosed with inoperable, stage IV pancreatic cancer. She was treated with combination chemotherapy comprising Reolysin (reovirus serotype-3 Dearing strain), carboplatin, and paclitaxel. After 4 months of treatment, her tumor had decreased in size by 55 %, and CA19-9 levels had dropped 25-fold. However, 7 months after her initial cancer diagnosis, she presented with clinical symptoms and radiographic findings consistent with leptomeningeal carcinomatosis. Lumbar puncture did not reveal malignant cells in the cerebrospinal fluid (CSF), and biopsy was requested for tissue diagnosis. This confirmed pancreatic leptomeningeal carcinomatosis. Our case report demonstrates that leptomeningeal spread from pancreatic tumors may develop independent of focal brain parenchymal involvement and in the setting of controlled systemic disease. Furthermore, the present study describes the first case of CNS progression in the setting of systemic response to Reolysin therapy, suggesting this newly developing treatment may not prevent neurological spread of disease. If repeat cytology of CSF fails to detect malignant cells, biopsy should be pursued for definitive diagnosis. Surgery may also concurrently provide an opportunity to place an intraventricular catheter for delivery of intrathecal chemotherapies.