ABSTRACT
N on-Hodgkins lymphomas (NHL) represent a large, clinically, morphologically and biologically diverse spectrum of malignant neoplasms. The classification and diagnosis of NHLs are a traditionally difficult problem for both pathologists and hematologists. One circumstance accounts for the difficulties is that neoplastic lymphoid cells often share morphologic, imunophenotypic and molecular features with those of normal lymphoid cells. The second circumstance is the lack of complete knowledge and understanding the maturation and differentiation of the normal hematopoietic and immune system. The new scientific re sults that has appeared during the past decades on the hematopoietic and immune system have generated time to time scientific basis for the discovery of new lymphoma entities and created new lymphoma classifications. In 1994 the International Lymphoma Study Group published a consensus proposal for the classification of lymphoid neoplasms named Revised European American Lymphoma (REAL) classification.1 This is based on the principle that the classifica tion is a list of “real” entities defined by the combination of morphology, immunophenotype, genetic and clinical features. Since 1993, members o f the European and American Hematopathology Societies have been collaborating on a new W HO classification of lympho mas. This classification is an updated version of REAL representing the first international con sensus on the classification of lymphomas.2
