Biopathologic features of Hodgkin's disease.

The neoplastic nature of Hodgkin's disease (HD) is suggested by several lines of evidence, including aggressive clinical course, presence of proliferating atypical cells morphologically recognized as Hodgkin's and Reed-Sternberg cells (H-RS), aneuploidy, and, in the minority of cases, clonality. Nevertheless, the etiopathogenesis of HD still remains elusive, and probably diverse. This uncertainty is partly due to the peculiar histology of HD lesions, characterised by the paucity of the putative neoplastic cell component, i.e. H-RS cells, admixed to a variety of reactive cells which prevent an exhaustive investigation at molecular level. Nevertheless, the possible involvement of different molecules with oncogenic potential has been recently suggested on the basis of immunohistological and molecular biology studies. These include oncogenes such as bcl-2 and MDM2 and anti-oncogenes such as p53. In addition, a large amount of data has accumulated on the possible role of EBV infection in HD. The colonization of lymphoid tissues by immortalized H-RS cells can account for the derangement of cytokine networks leading to microenvironmental and systemic abnormalities. In addition, a variety of soluble receptors (sIL-2R, sCD30, sTNF-R), and adhesion molecules (sICAM-1) are abnormally produced at sites of disease involvement. Some of these molecules still retain the ability to bind their ligands and can potentially contribute to the derangement of immune mechanisms observed in HD. Many of these soluble molecules can also be found in the patient's sera providing new potential prognostic and follow-up parameters in HD patients. The comparative analysis of the same molecules within the tissue, using immunohistochemistry, and in the blood, using immunochemical assays, appears as a promising informative approach.