Carcinomatous meningitis is a devastating metastatic complication of systemic carcinoma, which may occur insidiously, accompanied by a confusing spectrum of clinical symptoms and signs. In the absence of reliable diagnostic tumour markers, the diagnosis is established by the demonstration of malignant cells within the cerebrospinal fluid (CSF). Cytological techniques requiring skillful interpretation are occasionally negative in the presence of established disease, and when positive may indicate leptomeningeal malignancy of such advanced nature that effective palliation is difficult. Biochemical tumour marker technology offers the potential of reliable diagnosis in early disease states, prior to the appearance of exfoliated malignant cells, In a series of 100 patients, we assayed for an epithelial associated glycoprotein (HMFG I antigen) in CSF obtained at lumbar puncture. In 18 of 20 patients with carcinomatous meningitis, this high-molecular-weight glycoprotein was detectable in the CSF. The antigen was also present in 2 patients with neoplastic meningitis complicating lymphoma and medulloblastoma, but was not detected in the CSF of the remaining 78 patients.
Neoplastic meningitis occurring as a manifestation of metastatic carcinoma (carcinomatous meningitis) has been increasingly well recognized following improved methods of systemic therapy. The diagnosis is confirmed by the demonstration of malignant cells in the CSF and standard cytological techniques have been significantly enhanced by monoclonal antibody immunocytology (Coakham et al., 1984b). In the absence of known malignant disease, the disorder may present as a chronic progressive meningitis, requiring differential diagnosis from other causes such as tuberculosis and fungal infection. Cytological confirmation of neoplastic meningitis is still occasionally achieved with great difficulty and often reflccts advanced meningeal disease. Biochemical assays for tumour markers within the CSF have the potential to achieve a reliable diagnosis in the presence of minimal disease (Schold et al., 1980). Unfortunately, no biochemical assay system exists that combines adequate sensitivity and specificity for the reliable diagnosis of neoplastic meningitis. We have recently investigated CSF levels of an epithelium-associated glycoprotein (HMFGl antigen) in a group of 100 patients, 20 of whom had carcinomatous meningitis. Evidence is presented to support the high degree of sensitivity and specificity of a radioimmunoassay for HMFG1 in the diagnosis of carcinomatous meningitis.
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