A study of the association of Epstein‐Barr virus with Burkitt's lymphoma occurring in a Chinese population

There is a strong association (approximately 95%) of endemic Burkitt's lymphoma with Epstein‐Barr virus (EBV), whereas the association is weak for the sporadic form occurring in Western countries (approximately 15%). In the Middle East, North Africa and South America, 60–80% of Burkitt's lymphomas harbour EBV. These epidemiological differences suggest that either the endemicity of EBV or socio‐economic conditions, or both, may influence the pathogenetic role of EBV in Burkitt's lymphoma. Since only meagre data are available on Asians, this study was performed to address this issue by studying cases from Hong Kong, where EBV seroconversion occurs in the first few years of life but the socio‐economic conditions approach those of Western countries. In situ hybridization for EBV encoded RNAs (EBERs) was performed on paraffin sections of 18 cases of Burkitt's lymphoma. Labelling of the neoplastic cells was detected in five cases (27.7%). In contrast, among 54 cases of B‐cell lymphomas of various subtypes studied for comparison, signals for EBER were detected in only one case each of T‐cell‐rich large B‐cell lymphoma, anaplastic large cell lymphoma and Reed‐Sternberg‐like cells occurring in B‐cell chronic lymphocytic leukaemia/small lymphocytic lymphoma. The strong labelling with oligo‐dT probe (which hybridized with the polyadenylated ends of mRNA) in all cases suggested that the negative results were genuine and not due to poor preservation of RNA in the tissues. Thus, among B‐cell neoplasms occurring in Chinese, Burkitt's lymphoma shows a statistically stronger association (P < 0.01) with EBV than with other types of B‐cell lymphoma. The available data also suggest that the socio‐economic status of the country rather than exposure to EBV at an early age is the crucial factor determining the role of EBV in the genesis of Burkitt's lymphoma.