Gerstner and Batchelor Article indicate that primary central nervous system lymphoma (PCNSL), an uncommon variant of extranodal non-Hodgkin lymphoma, can affect any part of the neuraxis including the eyes, brain, leptomeninges, or spinal cord. Primary central nervous system lymphoma accounts for approximately 3% of all the primary central nervous system tumors diagnosed each year in the United States. Owing to the rarity of PCNSL, the disease has been challenging to study and an effective standard of care has been difficult to establish. Unfortunately, although durable remissions may be achieved for some patients with PCNSL, the tumor relapses in most cases. In this review, they focus on PCNSL in the immunocompetent host.