Hodgkin's disease.

The epidemiological features of Hodgkin's disease (HD) suggest that it is a heterogeneous condition which may have different aetiologies in different age groups. The risk factors for the development of HD in young adults suggest that delayed exposure to a common infectious agent may be involved in this age group. Seroepidemiological studies have shown that HD patients have elevated antibody titres to Epstein-Barr virus (EBV) and the elevated titres have been shown to precede the diagnosis of HD. Recent molecular studies provide support for the idea that EBV is involved in the pathogenesis of HD. EBV genomes are consistently found in a proportion of tumour biopsies, the EBV-infected cells are clonal and the EBV genomes have been localized to Reed-Sternberg cells. Furthermore, EBV latent gene products are expressed by the Reed-Sternberg cells. The majority of HD samples from patients aged greater than 50 years and less than 15 years are EBV positive, whereas the minority (less than 15%) of samples from young adults contain detectable EBV DNA. The results suggest that EBV plays a role in HD in children and older adults but that other agents, possibly other viruses, are involved in young adults.