Editorial Peripheral T-cell lymphoma: A developing concept

For a long time T-cell lymphomas (TCLs) were thought to be limited to southern Japan and some parts of China and the Caribbean [1-3]. As a result, they gained no mention in the Working Formulation [4], and were only rather rudimentarily treated in the Updated Kiel Classi-fication [5, 6], where their categorisation was based on pure morphology and the existence of new emerging entities was not taken into account. In this context, they gave rise to very poor inter- and intra-personal reprodu-cibility [7]. In 1994, the proposal of the Revised Euro-pean-American Lymphoma (R.E.A.L.) Classification by the members of the International Lymphoma Study Group [8] (Table 1) aroused new interest in TCLs. The R.E.A.L. Classification was conceived as a list of distinct clinico-pathological entities that could be distinguished by the available techniques [8]. A few of these entities were regarded as 'provisional ' in the absence of extensive experience or complete consensus within the Group [8]. Two other underlying principles of the R.E.A.L. Classi-fication were that all lymphoid tumors should be in-cluded, irrespective of their solid or leukaemic nature, or of their nodal or extranodal primary location, and that following the assumption that within each category aggressiveness varies from patient to patient, no indica-tion should be given as to the grade of malignancy [8]. Following its initial proposal, the R.E.A.L. Classifi-cation has proved its clinico-pathological relevance, easy Table 1. Categorisation of T-cell lymphomas according to the R.E.A.L. Classification. T-cell and putative NK-cell neoplasm