Primary Central Nervous System Lymphoma

Primary central nervous system lymphoma (PCNSL) is characterized by extranodal malignant lymphomas arising in the brain, spinal cord, CSF, and eyes in the absence of lymphoma outside the nervous system at the time of diagnosis (Deckert & Paulus, 2007). By definition, this excludes CNS involvement of systemic lymphomas and angiotropic lymphomas (Schlegel et al., 2000). The incidence of PCNSL in the United States was noted to be increasing in immunocompetent, immunosuppressed, and immunodeficient individuals over the past several decades (Schabet, 1999) with more than six-fold increase from 1973 to 1997, while the incidence of non-Hodgkin lymphoma (NHL) increased 81% during the same period (Olson et al., 2002). However, this increase in incidence seems to be leveling off in the past decade. According to the most recent Central Brain Tumor Registry Statistical Report (February 2011), PCNSL occurs at an annual incidence of 0.46 cases per 100,000 person-years in the United States during 2004-2007. PCNSL accounted for 2.4% of all primary brain tumors in the United States. There is a slight male predominance with a maleto-female ratio of 1.38. The peak incidence is between age 75 and 84. The median age in most studies is 55-65. The age at diagnosis in AIDS patients is much younger with mean age reported in the fourth decade (Deckert & Paulus, 2007; Fine et al., 1993).