Background: High frequency of Epstein-Barr virus (EBV) in the normal mucosa of the upper aerodigestive tract suggests that it may serve as a reservoir for the virus. Malignant lymphomas arising in this site may be associated with EBV.
Objectives: To determine the prevalence of EBV infection in extranodal malignant lymphomas of the upper aerodigestive tract.
Setting: King Chulalongkorn Memorial Hospital, Thailand.
Design: Descriptive study.
Patients: 42 Thai patients who presented between 1998 and 2003.
Material and Method: The expression of EBV mRNAs (EBERs) of malignant lymphoma was studied by means of in situ hybridization in formalin-fixed, paraffin-embedded specimens.
Results: The recruited subjects were 26 males and 16 females, and their age ranged from 3 to 85 years with the mean of 51.43 years, in 4 of them human immune deficiency virus (HIV) infection was documented. Ten of 42 cases (23.81%) expressed EBER transcripts and were extranodal NK/T-cell lymphomas, nasal type (7 cases), plasmablastic lymphomas (2 cases) and diffuse large B-cell lymphoma (1 case). Three of 4 cases (75%) of known HIV-seropositive cases were EBV-positive (2 plasmablastic lymphomas and 1 diffuse large B-cell lymphoma).
Conclusion: In the upper aerodigestive tract, EBV was present in some but not all malignant lymphoma. It was associated with extranodal NK/T-cell lymphoma, nasal type and B-cell lymphoma arising in HIV-infected patients, but it was not found in B-cell lymphoma arising in immunocompetent patients.

Keywords: Epstein-Barr virus, EBV, EBER, Lymphoma, HIV, Upper aerodigestive tract, Extranodal, In situ hybridization, Bangkok, Thai, Thailand