RARE-39. INTRAVASCULAR LYMPHOMA AFFECTING THE CENTRAL NERVOUS SYSTEM: FEATURES AND OUTCOMES IN A CASE SERIES OF THE PRIMARY CNS LYMPHOMA COLLABORATIVE GROUP (IPCG)

Abstract

Intravascular lymphoma (IVL) is a rare subtype of extranodal lymphoma, usually of the large B-cell type. It constitutes a subtype of primary central nervous system (CNS) diffuse large B-cell lymphoma (PCNSL) when it is confined to the vascular lumina of the CNS. In this International PCNSL Collaborative Group (IPCG) effort, we describe the clinical features and treatment outcomes of patients diagnosed with IVL affecting the CNS. We present a retrospective case series of 72 adults with IVL from 16 cancer centers in 6 countries. IVL was present in the CNS in 55 cases, with a mean age of 61.6 years and more than 90% of patients having neurological deficits at the time of diagnosis. There was a mean diagnostic delay of 20 weeks after presentation of stroke-like symptoms or myelopathy. Eighty-five percent had a poor functional status with an Eastern Cooperative Oncology Group (ECOG) performance status >=2 with another eight percent diagnosed post-mortem. Serum LDH was elevated in 87% of available patients with no correlation with treatment outcome. Frontline treatment with intravenous high-dose methotrexate-based combination therapy was the most common first line treatment in the presence of CNS disease. Seventy-two percent of patients receiving any regimen reached one-year survival. There is improved one-year survival for patients having received a regimen containing highdose methotrexate therapy with or without rituximab vs. non-methotrexate containing combination therapy (OR = 0.0667 95% CI 0.006-0.7451, P=0.028). The median progression free survival in patients treated with combination methotrexate and rituximab is at least 52 months. Multivariate analysis examining prognostic factors for outcome will be updated at time of presentation. This is the first case series to report improved prognosis in intravascular lymphoma with CNS involvement using combination highdose methotrexate with rituximab.