10291- ML-17 EXPRESSION OF ICAM-1,INTEGRINΒ1 IN INTRAVASCULAR LARGE B-CELL LYMPHOMA WITH CNS

Abstract BACKGROUND Intravascular lymphoma (IVLBCL) is generally characterized by growth within the microvasculature of extralymphatic organs and lack of invasion into the vessel wall or extravascular space. We experienced a case of concomitant intracranial DLBCL without IVL findings during the course of treatment for IVLBCL. Such cases are rare but have been reported in the past, and the origin of the tumor and the mechanism of metastasis are unknown. We investigated pathologically the deletion of cell adhesion molecules (ICAM-1, integrinβ1), which is considered to be a characteristic feature of IVLBCL, in this case. METHODS Among the cases treated at our hospital, 2 cases developed central nervous system intravascular lymphoma (CNS-IVL) after developing IVLBCL, 1 case developed CNS-IVL and subsequently relapsed cutaneous IVL, and 20 other PCNSL cases that followed the usual course of the disease were examined for ICAM-1 and integrinβ1 The histological characteristics of the 20 PCNSL cases were examined by immunostaining for ICAM-1 and integrinβ1. RESULTS In normal PCNSL, ICAM-1 and integrinβ1 were strongly expressed around blood vessels and tumor cells, and were absent in areas diffusely infiltrated into the brain parenchyma. In contrast, ICAM-1 and integrinβ1 in tumor cells were generally absent in patients with concomitant IVLBCL. DISCUSSION Deletion of cell adhesion molecules in IVLBCL is considered to be a factor that prevents invasion of vascular endothelium and loss of migration to lymph nodes. Interestingly, even in PCNSLs without evidence of IVL, there are areas of weak expression of cell adhesion molecules, suggesting that phenotype may be altered during the invasion process. The amount of specimens obtained from random skin biopsies is often extremely small. Therefore, histological findings will continue to be important.