Chromosomal abnormalities of intravascular large B-cell lymphoma (IVLBCL), a rare form of extranodal diffuse large Bcell lymphoma, have been described in only a small number of cases. A 59-year-old female presented with pancytopenia and splenomegaly. Bone marrow was normocellular with 30.4% abnormal large lymphoid cells that were positive for CD5, CD19, CD20, HLA-DR and λ chain. Bone marrow biopsy showed intrasinusoidal infiltration of large lymphoid cells. G-banding and spectral karyotyping of the bone marrow cells demonstrated a complex karyotype as follows : 48,XX,-8,+r(11),+12,del(12)(p?) ×2,+18,der(19)(19?::p13→qter),der(21)t(8;21)(q11.2;p11.2). Fluorescence in situ hybridization on interphase nuclei revealed three signals of CCND1 at 11q13, but two signals of BIRC3 at 11q22 and MLL at 11q23, indicating that r(11) contained CCND1. Together with other reported cases, our results indicate that the gain of 11q as well as trisomy 18 may be among the recurrent chromosomal aberrations in IVLBCL. Furthermore, an additional ring chromosome 11 could be a novel mechanism leading to the gain of 11q. [J Clin Exp Hematop 53(2) : 161-165, 2013]