The diagnostic value of cerebrospinal fluid pleocytosis and protein in the detection of lymphomatous meningitis in primary central nervous system lymphomas.

The exact rate of lymphomatous meningitis in primary central nervous system lymphomas (PCNSL) is uncertain. In this prospective multicenter study, cerebrospinal fluid (CSF) from 116 immunocompetent patients with newly diagnosed PCNSL was evaluated. Lymphoma cells were found in 18.1%, protein elevation (>45 mg/dL) in 65%, and CSF pleocytosis (>5/microL) in 36% of patients. Pleocytosis correlated with positive cytology, whereas CSF protein did not (specificity cell count vs. protein 74% vs. 34% [p<0.001], sensitivity 86% vs. 62% [p=0.18]).