Whole-Genome Analysis and HLA Genotyping of Enteropathy-Type T-Cell Lymphoma Reveals 2 Distinct Lymphoma Subtypes

Abstract

Enteropathy-type T-cell lymphoma (ETL) is an aggressive extranodal T-cell non-Hodgkin lymphoma assumed to arise in the setting of celiac disease. To precisely define the genetic alterations underlying the pathogenesis of ETL, 30 ETL samples were profiled for genetic copy number alterations using high-resolution whole-genome tiling path array comparative genomic hybridization. To investigate the potential association of genetic alterations in ETL with celiac disease, HLA-DQB1 genotyping was performed. By array comparative genomic hybridization, 13 novel recurrent minimal regions of chromosomal alteration were identified on multiple chromosome arms. ETL is characterized by frequent complex gains of 9q31.3-qter (70% of cases), or by an almost mutually exclusive 2.5-megabase loss of 16q12.1 (23% of cases). Two distinct groups of ETL could be delineated morphologically and genetically: type 1 ETL is characterized by nonmonomorphic cytomorphology, CD56 negativity, and chromosomal gains of 1q and 5q. Type 1 ETL also appears to be linked pathogenetically to celiac disease, sharing genetic alterations and HLA-DQB1 genotype patterns with (refractory) celiac disease. Type 2 ETL shows monomorphic small- to medium-sized tumor cell morphology, frequently shows CD56 expression, MYC oncogene locus gain, and rare gains of chromosomes 1q and 5q. In contrast to type 1 ETL, type 2 ETL shows a HLA-DQB1 genotype pattern more resembling that of the normal Caucasian population. Contrary to current clinical classification, ETL comprises 2 morphologically, clinically, and genetically distinct lymphoma entities. In addition, type 2 ETL may not be associated with celiac disease.