Rationale of a new classification for the group of primary cutaneous lymphomas

In the last decade many studies showed that primary cutaneous lymphomas hav e another clinical behavior and prognosis, and therefore require a differen t therapeutic approach, as compared with their primary nodal equivalents. B ecause, until recently, classification systems for non-Hodgkin's lymphomas were purely based on histologic criteria, and did not recognize the special character of these lymphomas, primary cutaneous lymphomas were not uncommo nly diagnosed incorrectly and/or treated inappropriately with unnecessarily aggressive therapies. For that reason the Cutaneous Lymphoma Group of the European Organization for Research and Treatment of Cancer (EORTC) proposed a separate classification for the group of primary cutaneous lymphomas. Th is EORTC classification is consistently based on a combination of clinical, histologic, immunophenotypical and genetic criteria, and includes well-def ined and recognizable disease entities. It contains a limited number of cut aneous T-cell lymphomas and cutaneous B-cell lymphomas, which together cons titute more than 95% of all primary cutaneous lymphomas, Herein, the ration ale and the basic principles of the EORTC classification are presented, and the relationship between the EORTC classification and other recent classif ication systems, such as the Revised European-American Classification for L ymphoid Neoplasms (REAL classification) and the proposed World Health Organ ization classification, are discussed. Copyright (C) 2000 by W.B. Saunders Company.