Leptomeningeal cancer (also called leptomeningeal carcinomatosis, leptomeningeal disease (LMD), leptomeningeal metastasis, neoplastic meningitis, meningeal metastasis and meningeal carcinomatosis) is a rare complication of cancer in which the disease spreads from the original tumor site to the meninges surrounding the brain and spinal cord. This leads to an inflammatory response, hence the alternative names neoplastic meningitis (NM), malignant meningitis, or carcinomatous meningitis. The term leptomeningeal (from the Greek lepto, meaning 'fine' or 'slight') describes the thin meninges, the arachnoid and the pia mater, between which the cerebrospinal fluid is located. The disorder was originally reported by Eberth in 1870.