Differential diagnostic aspects in malignant lymphomas involving the central nervous system.

Neoplastic cells were found in the cerebrospinal fluid (CSF) cytograms in 57% of patients with lymphocytic leukemia and reticulum cell sarcoma. Tumor cells may be observed in CSF specimens showing normal cell count and total proteins. Quantitative and/or qualitative changes in CSF proteins in absence of corresponding abnormalities in serum may indicate a malignant lymphorproliferative process involving the central nervous system even in absence of neoplastic cells.