Non-inverted Duplication of 11q, dup(11)(q11q24), in a Diffuse Large B Cell Lymphoma Without MYC Rearrangement: Case Report

The 2017 revision of the World Health Organization classification of lymphoid neoplasms defined a new provisional entity, Burkitt-like lymphoma with 11q aberration (BLL-11q). BLL-11q lacks MYC rearrangement but has a chromosome 11q-gain/loss due to an inverted duplication event such as dup(11)(q23q13). Despite this classification, the association between 11q aberration and diffuse large B cell lymphoma (DLBCL) has not been fully characterized. Here, we describe an unusual case of DLBCL that presented as dup(11)(q11q24) without MYC rearrangement. A 68-year-old woman with left cervical lymphadenopathy was admitted to our hospital. Lymph node biopsy revealed diffuse proliferation of atypical large lymphoid cells positive for CD20, CD10, BCL6, MUM1, and BCL2, which led to a diagnosis of DLBCL. G-banding showed 46,X,-X,+7,dup(11)(q11q24),del(20)(q1?). Fluorescence in situ hybridization (FISH) detected duplicated CCND1 signals at 11q13.3 and duplicated KMT2A signals at 11q23.3 with similar intervals on dup(11)(q11q24). These results indicated that the chromosomal aberration was a simple duplication without inversion. FISH did not detect split MYC signals. Almost all cells were negative for MYC and CCND1. In contrast to BLL-11q, DLBCL seems to have a non-inverted simple duplication without terminal deletion. Thus, the distinction between an inverted duplication and a simple duplication by metaphase FISH is crucial, since the resultant genetic changes and disease phenotypes are different. Duplication of genes including KMT2A located on 11q may contribute to the pathogenesis of DLBCL.