血管内大細胞型B細胞リンパ腫の中枢神経病変に対する治療戦略

Treatment Strategy for Central Nervous System Involvement in Intravascular Large B-cell Lymphoma

はじめに

　血管内大細胞型B細胞リンパ腫（intravascular large B-cell lymphoma：IVLBCL）は血管内に選択的に腫瘍細胞が増殖する稀な悪性リンパ腫の一型である。2008年秋に改訂されたWHO分類（第4版）において独立した疾患概念となったこの特異な病型は^1），近年の診断技術の向上と疾患概念の普及に伴って生前診断率が向上しつつあり，治療においても多くのB細胞リンパ腫と同様に，抗CD20モノクローナル抗体医薬であるリツキシマブの登場によって治療成績が向上していることが示されている。病型の特徴として初発時および再発時において中枢神経病変をきたしやすいことが知られており，特に中枢神経進展・再発は，治療成績が向上しつつある現在においても大きな課題であると考えられている。本稿においては，IVLBCLにおける治療成績および中枢神経病変について概説し，同病変に対する治療戦略について論じてみたい。

Abstract

　Intravascular large B-cell lymphoma (IVLBCL) is a distinct disease entity of non-Hodgkin lymphoma which is characterized in the current WHO classification by the selective growth of tumour cells in the lumina of small vessels of various organs.　This rare disease entity has a high incidence of central nervous system (CNS) involvement at diagnosis.　Although several retrospective analyses indicate that the treatment of this lymphoma has improved in the post-rituximab era,risk of CNS recurrence at 3 years still reaches ～25%.　Considering the poor prognosis of IVLBCL patients with CNS recurrence,elucidating the optimal treatment strategies for this serious complication is vital in order to further improve its clinical management.　Meanwhile,the efficacy of CNS prophylaxis for specific subtypes of lymphoma,for example Burkitt lymphoma and acute lymphocytic leukemia/lymphoblastic lymphoma,has been established,and several risk factors of CNS relapse for diffuse large B-cell lymphoma (DLBCL) were indicated by previous analyses.　Considering that almost all IVLBCL patients have similar risk factors,CNS prophylaxis could also be effective,and thereby give rise to better clinical outcomes,in the treatment of IVLBCL,especially for patients without CNS involvement at initial diagnosis.　Intensity regimens for CNS and systemic chemotherapy could be useful for patients with CNS involvement at initial diagnosis.　This review describes the current understanding of clinical outcome and CNS involvement in IVLBCL,and discusses the optimal treatment strategy and future perspectives for CNS involvement of this rare lymphoma.