Multistep tumorigenesis in peripheral T cell lymphoma.

Peripheral T cell lymphomas (PTCL) are classified as mature T cell neoplasms. However, several new findings support the notion that premalignant cells arise in the immature stage of hematopoietic differentiation, and subsequently evolve into full-blown T-lineage tumor cells. Acquisition of (Ten-Eleven Translocation 2) TET2 mutations may be an important event for the establishment of premalignant cells. In PTCL harboring features of follicular helper T cells, tumor-specific G17V RHOA mutations co-occur with premalignant TET2 mutations. The G17V (ras homolog family member A) RHOA mutations may play important roles in clonal evolution of premalignant cells into tumor cells. Indeed, multistep tumorigenesis is thought to be essential for pathogenesis of PTCL.