<unk>  is an intracranial tumor usually present in those with severe immunosuppression. It represents around 20% of all cases of<unk> s in HIV infection (other types being Burkitt's<unk>  and immunoblastic<unk> .<unk>  may originate from a germinal center to an early postgerminal center in a secondary lymphoid organ, which may be capable of further maturation steps. EBV is almost always associated with<unk>  in immunodeficient individuals, and latent EBV infection of B-cells leads to it's immortalization and to CNS tropism. In immunocompetent individuals, the B-cells infected with EBV are held in check by T-cells, and with the severity of immunosuppression, T cells gradually fall, leading to the B-cell proliferation and dissemination. .<unk>  constitutes approximately 3%-4% of all<unk>  brain tumors and 1%-2% of all<unk> s.<unk>  has been diagnosed in at least 2% of individuals infected with human immunodeficiency virus, and in 9–14% of acquired immunodeficiency syndrome (AIDS)-autopsies.<unk>  is, after toxoplasmosis, the most common cause of focal brain lesions in AIDS patients. The overall incidence of<unk>  is 0.4 per 100,000 individuals per year. The median age of occurrence of<unk>  in immunocompetent and immunocompromised patients are 53-57 years and 31-35 years, respectively. The peak incidence is between 60 and 70 years old for immunocompetent patients. Significant increment of incidence rate over time is associated with increased incidence of AIDS and advanced age. Males are more commonly affected with<unk>  than females.
Primary central nervous system lymphoma
Idiopathic inflammatory demyelinating diseases
Intracerebral metastases
Neoplastic meningitis
Progressive multifocal leukoencephalopathy
Adult brain tumors
Limbic encephalitis
Paraneoplastic cerebellar degeneration