TET2 germline mutation in a patient with sequential lymphoid malignancies: a novel case report.

We report a case of a 30-year-old male patient with a germline heterozygous TET2 R1354fs mutation, who successively developed three distinct lymphoid malignancies: mixed cellularity classical Hodgkin lymphoma (MCCHL), angioimmunoblastic T-cell lymphoma (AITL), and T-cell acute lymphoblastic leukemia (T-ALL). Sequencing analysis of the oral mucosa and bone marrow specimens during the remission phase confirmed the germline origin of the TET2 mutation. This represents the first documented case of the sequential transformation across three distinct lymphoid malignancies attributable to a germline TET2 mutation, underscoring its pivotal role in lymphomagenesis and clonal evolution.