Delayed diagnosis and brain biopsy in central nervous system intravascular large B-cell lymphoma: a three-patient case series

Central nervous system intravascular large B-cell lymphoma (CNS IVLBCL) is a rare, aggressive lymphoma that can mimic inflammatory, infectious, demyelinating, and vascular disorders.We describe three patients with pathologically confirmed CNS IVLBCL who presented with progressive neurological symptoms and nonspecific magnetic resonance imaging abnormalities that worsened over time.Initial working diagnoses included viral or autoimmune encephalitis, cerebral infarction, and inflammatory or demyelinating disease.All patients received corticosteroids before tissue diagnosis, and two had transient clinical improvement.Brain biopsy established the diagnosis 10 months after symptom onset in Cases 1 and 2 and 15 months after symptom onset in Case 3. By the time of diagnosis, functional status had declined in all patients, and two were bedridden.Methotrexate-based or rituximab-containing chemotherapy was initiated, but all patients died 11-16 months after symptom onset, primarily because of infectious complications.These cases shared a diagnostic pattern of progressive neurological deterioration, inconclusive conventional investigations, radiological progression despite empirical treatment, and potentially misleading corticosteroid responsiveness.When these features coexist, CNS IVLBCL should remain in the differential diagnosis, and brain biopsy should be considered before severe functional decline limits tolerance to intensive treatment.