High incidences of malignant lymphoma in patients infected with hepatitis B or hepatitis C virus.

It is still not clear whether there is an association between malignant lymphomas and hepatitis B or hepatitis C virus infections. Most studies from Italy and Japan support this association, but studies from other countries generally do not. We conducted a hospital-based case-control study to evaluate this association and show a significant association between the development of malignant lymphoma and infections by these viruses.