Cryptic NUP214-ABL1 fusion with complex karyotype, episomes and intra-tumor genetic heterogeneity in a T-cell lymphoblastic lymphoma

Abstract

T-lymphoblastic lymphoma (T-LBL) is a rare and aggressive form of non-Hodgkin’s lymphoma and little is known about their molecular background. However, complex karyotypes were already related to this group of malignancy and associated with poor outcome. Here, we describe a 17-year-old female being diagnosed with T-LBL and a normal karyotype after standard G-banding with trypsin-Giemsa (GTG)-banding. However, further analyses including high-resolution molecular approaches, array-comparative genomic hybridization (aCGH), multiplex ligation-dependent probe amplification, fluorescence in situ hybridization and multicolor chromosome banding revealed a cryptic complex karyotype, NUP214-ABL1 gene fusion, episomes and intra-tumor genetic heterogeneity. In addition, homozygous loss of CDKN2A, as well as amplification of oncogene TLX1 (HOX11) were detected. Actually, NUP214-ABL1 fusion gene replicated autonomously in this case as episomes. Overall, highly amplification of NUP214-ABL1 fusion gene defines possibly a new subgroup of T-LBL patients which accordingly could benefit from treatment with tyrosine kinase inhibitors. As episomes are missed in standard karyotyping aCGH should be performed routinely in T-LBL to possibly detect more of such cases