Rare PTCLs: treatment lagging behind pathobiologic advances.

Peripheral T-cell lymphomas, or PTCLs, represent an uncommon and biologically heterogeneous group of hematologic malignancies, accounting for less than 10% of all non-Hodgkin lymphomas worldwide, with marked geographic differences. Due to their low prevalence, variable clinical presentation and phenotypic heterogeneity, these lymphomas have historically been difficult to diagnose and categorize. Since the introduction of immunophenotyping and molecular genetic methods, as well as the development of comprehensive classification systems, there have been significant advances in diagnostic accuracy, classification, and our understanding of the biologic behavior of different PTCL subtypes. However, the molecular pathogenesis of most subtypes of PTCL remains incompletely understood, and treatment outcomes with conventional anthracycline-based chemotherapy regimens are generally significantly inferior to those in aggressive B-cell lymphomas.