Progress in the classification of hematological neoplasms. From REAL to WHO concept

Recent advances in immunology, molecular biology and cytogenetics as well as the development of new diagnostic techniques set out the necessity for the redefinition and reclassification of hematological malignancies. Therefore, WHO in 1995 assigned the Society of Hematopathology and European Association for Hematopathology to create a new classification of these neoplasms. The result of collaborative efforts of leading hematopathologists from both organizations is the World Health Organisation (WHO) classification of hematological neoplasms. WHO classification adopted basic concepts, defined criteria introduced by REAL classification of lymphoid neoplasms and extended them to myeloid, histiocytic and mastocytic neoplasms. WHO classification of hematological neoplasms is represented by a list of disease entities and its variants, opened for inclusion of new entities, updating of diagnostic criteria and changes of nomenclature. The clinical relevance of the proposed entities has been evaluated by the clinicians, members of Clinical Advisory Committee. The proposed classification is a challenge to the clinicians to create new treatment strategy, directed towards particular disease entities. The presentation of WHO classification in our review is limited to myeloid and lymphoid neoplasms.