CT and MRI scans are used to diagnose primary central nervous system lymphoma in persons with and without HIV. HIV infected persons tend to have multiple tumors on these imaging studies while those without HIV usually have a single mass.
Persons with HIV are vulnerable to infections as a result of their weakened immune systems. Therefore, when a mass is seen on CT or MRI, additional testing must be done to eliminate infection as the cause. These include testing for toxoplasmosis (a parasite that infects the brain of HIV-infected people) and Epstein-Barr virus (the virus associated with mononucleosis and primary central nervous system lymphoma in those with HIV). In addition, they may be given a trial of antibiotic therapy in order to eliminate infection as a possible cause.
As with persons not infected with HIV, a brain biopsy may be needed to confirm the diagnosis.