Peripheral T cell lymphoma

Abstract

Peripheral T cell lymphomas (PTCL) are post thymic T cell tumours which account for about 15-20% of non-Hodgkin's lymphomas in the Western world. Newly available methods of immunohistochemical, cytogenetic and molecular analysis have allowed a better characterisation of PTCL, although controversy still exists about their histo-morphologic and prognostic classification. As a matter of fact, the Kiel Classification, recently updated to include PTCL subgroups, does not separate PTCL into clearly defined prognostic categories. This problem might be primarily due to the wide histologic polymorphism that characterises PTCL and that does not allow a clear subdivision between slow-growing and aggressive subtypes according to morphologic appearance. The recently proposed Revised European-American Lymphoma Classification, accounting for this uncertainty regarding the role of histologic classification, lumps most PTCL in a 'common' subgroup. In the future, further immunologic and genetic characterisation should permit the recognition of better defined subentities. As regards clinical behaviour of T cell immunophenotype as opposed to B cell phenotype, retrospective analyses yield controversial results. Thus, at the moment it is not clear whether or not the therapeutic approach to PTCL should be more aggressive than that for B cell lymphomas. Future research should focus on the analysis of prospective case series homogeneously diagnosed and treated.