LEPTOMENINGEAL TUMOR IN PRIMARY CENTRAL-NERVOUS-SYSTEM LYMPHOMA - RECOGNITION, SIGNIFICANCE, AND IMPLICATIONS

The true incidence of leptomeningeal tumor in primary central nervous system lymphoma is unknown. We studied prospectively the cerebrospinal fluid profile of 96 patients without acquired immunodeficiency syndro me but with primary central nervous system lymphoma at diagnosis, at c ompletion of treatment, and at recurrence. Magnetic resonance images a nd pathology slides were examined for evidence of leptomeningeal tumor . Leptomeningeal tumor was diagnosed by (1) positive findings on cereb rospinal fluid cytology, (2) leptomeningeal or subependymal enhancemen t on magnetic resonance imaging, or (3) pathological evidence of lepto meningeal tumor. We recorded whether treatment directed against the le ptomeninges was given. Cerebrospinal fluid was examined in 86 of 96 pa tients at diagnosis and 29 of 42 at recurrence. The incidence of lepto meningeal tumor was 42% at diagnosis and 41% at recurrence. Only eleva ted levels of protein and lactate dehydrogenase isoenzyme-5 were signi ficantly associated with leptomeningeal tumor (p = 0.012, p = 0.016, r espectively). Treatment against the leptomeninges was significantly as sociated with the probability of achieving a complete response and a l onger freedom from relapse. Patients older than 50 years had a worse d isease-specific survival but a similar probability of responding to th erapy as younger patients. Our data show that leptomeningeal tumor in primary central nervous system lymphoma is more prevalent than origina lly thought, and indicate the need for therapy inclusive of the leptom eninges in all patients.