Can you tell me if it's unusual for Primary Central Nervous System Lymphoma to be the first illness in an hiv+ person? Don't other conditions precede such a condition?

Primary Central Nervous System Lymphoma typically occurs late in the course of AIDS. Usually such patients have CD4 counts less than 50. It is not uncommon to have patients present with this type of lymphoma. They are patients, who for a variety of reasons, have not sought out medical care previously. Often these patients who present with lymphoma as their first AIDS illness do quite well since they have never taken any HIV drugs so there is less chance of them having a resistant virus than someone who has been on drugs for over a decade. So to answer your question, "Is it unusual?"-- the answer is "No". That said, most patients in the United States have sought out medical care before their CD4 cells get so low; and for them, such a presentation of lymphoma would be a bit unlikely.