EATL : Molecular Genetics
Most cases of enteropathy-associated T-cell lymphoma (EATL) show clonal rearrangement of TRB or TRG genes. In addition, there is amplification of 9q34 region (harboring proto-oncogenes NOTCH1, ABL1, and VAV2) or deletion of 16q12.1 region. About 50% of EATLs show LOH at 9p21 locus, the site of cell-cycle inhibitor CDKN2A/B, resulting in loss of p16 protein expression. There is loss of 17p12-13.2 region containing TP53 in about 25% of cases; however, aberrant p53 expression is detected in almost 75% of cases. Recent studies suggest that deregulation of JAK-STAT signaling pathway may be an early event in the pathogenesis of EATL. This image of EATL shows an area of mucosal ulceration with extensive necrosis underneath. EATL frequently produces ulcerated nodules in the involved segement of the small bowel with an angiocentric and angioinvasive growth pattern.