World Health Organization Classification of tumors of hematopoietic and lymphoid tissues, 4th edition, 2008 - major changes from the 3rd edition, 2001.

The World Health Organization (WHO) Classification of tumors of hematopoietic and lymphoid tissues (4th edition, 2008)1 presents an updated version of the 3rd edition published in 2001(2). A summary of these changes relates to the groups of chronic myeloproliferative disorders, myelodisplasia, acute myeloid leukemias, neoplasms of precursor B and T cells and neoplasms derived of mature B, T and NK cells. A better understanding of molecular genetic changes and results achieved with innovative therapeutic approaches in these groups of diseases requires constant reassessment of the classifications, supporting the major changes discussed here, including interesting comments from literature (1, 3-5).