Abstract: |
The non-Hodgkin's lymphomas (NHLs) represent a group of diseases arising from clonal proliferation of lymphocytes. NHL is the most common hematologic malignancy, with an estimated new patient incidence of 54,000 with 14,000 deaths from disease,1 accounting for 4% of the new cancer diagnosed in 2004. The NHLs represent a diverse group of diseases with distinctive natural histories and clinical presentations.2 This diversity arises from the fact that each of the lymphomas is derived from distinct stages of the complex process of lymphocyte ontogeny. Morphology was the mainstay of diagnosis and classification of NHL for many years. In 1994, the authors of the Revised European and American Lymphoma (REAL)3 sought to create a classification system that defined distinct clinical entities. To accomplish this, the morphologic appearance was supplemented by the incorporation of additional information derived from immunophenotyping, genetics, and clinical features. This classification was the basis for the World Health Organization (WHO) classification of the neoplastic diseases of the hematopoietic and lymphoid tissues.4,5 There are 27 entities included in the WHO classification of the non-Hodgkin's lymphoid neoplasms; this number excludes subtypes and subcategories recognized in the WHO classification. The major categories of the WHO classification are shown in Table 68.1. © 2006 Springer Science+Business Media, Inc. |