Abstract: Objective To explore the clinical manifestations， imaging features， treatment effects and prognosis of relapsed primary central nervous system lymphoma. Methods Seventeen cases with relapsed primary central nervous system lymphoma treated in our hospital from June 2008 to June 2012 were retrospectively reviewed. Seven relapsed PCNSL patients were treated with highdose pemetrexed（900mg／m²）. Ten relapsed PCNSL patients were treated with temozolomide， nedaplatin and vincristin regimen, in addition， 3 of them were treated with local radiotheraphy with 2030Gy, 3 patients were treated with Ommaya reservoir placement and ventricular therapy with rituximab（30mg） through Ommaya reservoir were given after operation.
ResultsIn 17 patients, ectopic recurrence was found in 9 （52.9％）， recurrence in situ in 5 （29.4％）， leptomeningeal metastasis in 2 （11.8％）， lumbar vertebrae metastasis in 1 （5.9％）. Magnetic resonance spectroscopy showed Cho peak elevated and NAA, Cr peak declined in the solid area and peritumoral edema region, lip peak appeared obviously in the solid area. Complete remission in 6 of 17（35.3％）， partial remission in 4 of 17（23.5％） patients， stable disease in 5 of 17（29.4％）， progressive disease in 2 of 17（11.8％）， and overall response rate was 58.8％（10／17）. The median overall survival was 111 months from recurrence to death. There was no significant difference between temozolomidebased chemotherapy and pemetrexed chemotherapy（P＞0.05）. Conclusion Ectopic recurrence was the most common relapse pattern in relapsed PCNSL. The prognosis of relapsed PCNSL is very poor. The chemotherapy regimen with good efficacy and less side effects needes to be explored. But it is still needed to expand samples and increase cooperation of multicenter study， and the combined treatment with temozolomicle or pemetrexed is a meaningfull trial.