Diagnostic advances and new trends for the treatment of primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare non-Hodgkin's lymphoma arising in the brain. Recent increase in its incidence has been noted both in immunocompetent individuals and patients with immunodeficiency. This review will focus on the epidemiology, pathogenesis, diagnosis and treatment of this aggressive extranodal lymphoma in immunocompetent patients. Stereotactic biopsy is usually required for diagnosis, while molecular biology and/or cytofluorimetric analysis may confirm the presence of clonal proliferation in the cerebrospinal fluid (CSF). Methotrexate-based chemotherapy plus whole-brain radiotherapy are the standard treatment for PCNSL and achieve a high rate of complete remissions (CR), but long-term neurotoxicity may heavily compromise the patient's quality of life. The metabolic rate of controversial gadolinium-enhancing lesions on magnetic resonance (MR) scans may be assessed with positron emission tomography (PET), which discriminates radiation necrosis from true recurrence. Withholding radiotherapy in patients achieving CR after first-line chemotherapy is a new and interesting treatment option, while the role of high-dose chemotherapy with stem cell rescue is still uncertain.