 The purpose of this study is to evaluate several aspects of thinking abilities including attention and memory, and quality of life in patients who were diagnosed with and treated for Primary CNS Lymphoma PCNSL, and are in remission of their disease. The findings of this study may help us understand whether this disease and its treatment may have affected some patients thinking skills, and may provide important information that can be used to develop programs to improve the quality of life of patients with PCNSL. 