ABSTRACT
Peripheral T cell lymphomas (PTCLs) comprise a heterogeneous group of neoplasms that are derived from postthymic lymphoid cells at different stages of differentiation with different morphologic patterns, phenotypes, and clinical presentations.1 Peripheral T cell lymphomas are highly diverse, reflecting the diverse cells from which they originate. These include different types of T cells (αβ or γδ) and may have features of cytotoxic, helper, or suppressor lymphocytes, or they may present an aberrant phenotype.1-6
Notwithstanding progress in pathology, biology, and genetics, PTCLs remain difficult to classify for several reasons. Not only is the group as a whole rare, but it is divided into multiple subtypes, so that some of these neoplasms represent less than 1 percent of non-Hodgkin lymphomas (NHLs). Moreover, PTCLs lack a phenotypic marker of clonality, are morphologically heterogeneous, and show poor correlation between morphology and prognosis. Finally, the lack of diagnostic consensus has limited our knowledge of therapeutic experience, and PTCL overall and failure-free survival rates (OS and FFS) are still among the lowest of NHLs.7
