Non-Hodgkin lymphoma Primary central nervous system lymphoma Primary CNS lymphoma SNOMEDCT_US:21964009 SNOMEDCT_US:307649006 Primary central nervous system lymphoma (PCNSL) is defined as the involvement of brain, leptomeninges, cerebrospinal fluid, eyes or spinal cord by an extranodal non-Hodgkin lymphoma (NHL) without evidence of a systemic lymphoma at the time of diagnosis. It represents 0.8 to 6.6% of all primary CNS tumors A form of extranodal, high-grade non-Hodgkin B-cell neoplasm, usually large cell or immunoblastic type that originates in the brain, leptomeninges, spinal cord, or eyes and typically remains confined to the CNS. UMLS:C0280803