Primary diffuse large B-cell lymphoma of the central nervous system (DLBCL-CNS, also termed primary central nervous system lymphoma ) is a DLBCL in which diffuse patterns of neoplastic B-cells with centroblastic, immunoblastic, or poorly differentiated features infiltrate the brain, spinal cord, leptomeninges, or eye. The disease usually presents as a single lesion with a predilection for the supratentorial region of the brain but may involve the eye in 15–25% of cases, the cerebrospinal fluid in 7–42% of cases, and the spinal cord in ∼1% of cases. The disease has a 5-year overall survival rate of ~30%.