Redefining central nervous system multiple myeloma: From rare phenomenon to emerging entity

Central nervous system involvement in multiple myeloma (CNS-MM) is a rare, devastating extra-medullary disease associated with aggressive biology and poor survival, often less than six months. CNS-MM may represent a distinct biologic entity requiring dedicated strategies. Effective systemic treatments are limited by the blood-brain barrier. Future management must integrate novel diagnostics, such as CSF-based circulating tumor DNA, with CNS-penetrant therapies, and clinicians should screen high-risk patients.