Rare Variants of Primary CNS Lymphoma

Low-grade primary central nervous system lymphoma (PCNSL) is a rare variant of PCNSL. Although little is known about its precise incidence and clinical characteristics, the available data suggest that low-grade PCNSL may have a distinct clinical presentation, radiographic characteristics on magnetic resonance imaging, and prognosis as compared to classic high-grade PCNSL. Most importantly, survival data on low-grade PCNSL appear to be more favorable as compared to classic high-grade PCNSL, even with treatment strategies generally not considered efficient enough to treat classic high-grade PCNSL. T-cell PCNSL represents a small proportion of all PCNSL. The presentation and outcome seem to be similar to that of B-cell PCNSL. Good performance status and administration of methotrexate appear to be associated with improved survival. Pediatric PCNSL is extremely rare, and the optimal management is yet to be defined. Except for human immunodeficiency virus-related PCNSL, the prognosis for pediatric patients with this tumor appears to be significantly better than in adults. Most children with PCNSL can achieve long-term remissions with intensive chemotherapy alone (70% 5-year event-free survival), while cranial irradiation is usually reserved for relapsed disease. Further progress in the management of childhood PCNSL will require large prospective multinational trials.