Central Nervous System Lymphoma

Lymphoma of the central nervous system (CNS), both primary and secondary, represents a rare but highly aggressive subset of non-Hodgkin lymphoma (NHL). Despite its reputation for aggressiveness and poor prognosis, primary central nervous system lymphoma (PCNSL) often responds well to therapy and has the possibility of curative treatment. Increasingly, high-dose myeloablative therapy in combination with autologous stem cell transplantation and the advent of newer therapeutic strategies (eg, ibrutinib), offer the possibility of improved outcomes. PCNSL is a rare variant of extra-nodal NHL that can impact sites anywhere along the entire neuraxis, including the orbits, leptomeninges, brain, and spinal cord. On the other hand, secondary CNS lymphoma refers to systemic NHL that has disseminated to the CNS. Historically, the prognosis of PCNSL has been dismal, with overall survival of 1.5 months if untreated and a 5-year survival rate of 30%. Diffuse B-cell lymphoma is the most common form of PCNSL, usually localized to the parenchyma, but other locations are also possible, as previously described. The underlying histology and disease localization determine the neurologic presentation, treatment options, and prognosis. Patients with aggressive systemic NHL have a 2% to 27% risk of developing secondary CNS dissemination, with a median survival of 2.2 months after diagnosis. The introduction of high-dose methotrexate-based chemotherapy regimens has led to substantial progress in CNS lymphoma treatment and prognosis, including improved survival.