In that case, a first core biopsy had been diagnosed as an atypical lymphoproliferation and re-biopsy after four years without treatment showed histologically typical AITL with mutations in TET2, DNMT3A, and RHOA. In that case, it was not a question of limited tumor burden in the first biopsy, but rather poorly preserved morphology of what was clearly a lymphoma from the beginning, which remained clinically silent for several years. This evidence concerns the gene TET2 and lymphoma.