Primary central nervous system lymphoma differential diagnosis

Overview
Primary CNS lymphoma is a primary intracranial tumor usually present in those with severe immunosuppression --- commonly in those with AIDS --- and represents around 20% of all cases of lymphomas in HIV infection (other types being Burkitt's lymphoma and immunoblastic lymphoma). Primary CNS lymphoma (PCNSL) is highly associated with Epstein-Barr virus infection (> 90%) in immunodeficient patients (such as those with AIDS and those iatrogenically immunosupressed) and does not have predilections for any age group. Mean CD4+ count at time of diagnosis is ~50/uL. Because of the severity of immunosuppression at the time of diagnosis, it is to no surprise that prognosis is usually poor. In immunocompetent patients (that is, patients that do not have AIDS or some other immunodeficiency) there is rarely an association with EBV infection or other infectious DNAs. In the immunocompetent population, PCNSL typically affects older patients in their 50's and 60's.