Clinical meaning
Primary CNS lymphoma (PCNSL) is a rare, aggressive non-Hodgkin lymphoma arising within the brain, spinal cord, leptomeninges, or eyes without systemic lymphoma involvement. The vast majority are diffuse large B-cell lymphomas (DLBCL) occurring in immunocompromised patients (HIV/AIDS with CD4 less than 50 cells/microL, post-transplant immunosuppression) or immunocompetent elderly patients. The tumor typically presents as single or multiple contrast-enhancing lesions in periventricular white matter, deep gray matter (basal ganglia, thalamus), or corpus callosum, crossing the midline ('butterfly pattern'). Unlike most brain tumors, PCNSL responds dramatically to corticosteroids (which induce lymphocyte apoptosis), often showing near-complete radiographic resolution within days -- earning it the name 'ghost tumor.' However, this temporary response can delay definitive diagnosis if biopsy is performed after steroid administration. The nurse monitors neurological status, assesses for signs of increased ICP (headache, nausea, papilledema), administers prescribed corticosteroids while understanding they should be withheld before biopsy if possible, administers high-dose methotrexate-based chemotherapy per protocol with leucovorin rescue, monitors for methotrexate toxicity (mucositis, nephrotoxicity, hepatotoxicity, myelosuppression), implements seizure precautions, and provides supportive care during aggressive treatment regimens.