Assessing central nervous system (CNS) involvement in patients with lymphoma or carcinoma is important in determining therapy and prognosis. Progranulin (PGRN) is a secreted glycosylated protein with roles in cancer growth and survival; it is highly expressed in aggressive cancer cell lines and specimens from many cancer types. We examined PRGN levels by Enzyme Immuno-Assay (EIA) in cerebrospinal fluid (CSF) samples from 230 patients, including 18 with lymphoma [12 with CNS metastasis (CNS+); 6 without CNS metastasis (CNS-)], 21 with carcinomas (10 CNS+; 11 CNS-), and 191 control patients with non-cancer neurological diseases, and compared PRGN levels among these disease groups. Median CSF PGRN levels in the CNS+ lymphoma group were significantly higher than in the CNS- lymphoma and control non-cancer groups; and were also significantly higher in the CNS+ carcinoma group than in the CNS- carcinoma and control groups, except for patients with infectious neurological disorders. Receiver operating characteristic curve analyses revealed that CSF PGRN levels distinguished CNS+ lymphoma from CNS- lymphoma and non-cancer neurological diseases [area under curve (AUC): 0.969]; and distinguished CNS+ carcinomas from CNS- carcinomas and non-cancer neurological diseases (AUC: 0.918). We report here, for the first time, that CSF PGRN levels are higher in patients with CNS+ lymphoma and carcinomas compared to corresponding CNS- diseases. This would imply that measuring CSF PGRN levels could be used to monitor CNS+ lymphoma and metastasis.