MEITL : Molecular Genetics
T-cell receptor genes are clonally rearranged in more than 90% of cases of monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL). Gains at 8q24 locus (resulting in MYC amplification) and 9q34.3 locus are commonly found. Numerous other chromosomal aberrations (both gains and losses) have been documented in MEITL. Activating mutations in STAT5B and SETD2 have been found in the majority of cases of MEITL. Some cases also show mutations in JAK2 and GNAI2. EBV is negative; if positive, it should suggest an alternative diagnosis of extranodal NK/T-cell lymphoma. This image shows the monomorphic neoplastic infiltrate of T-cells in a case of MEITL.