A study of the possible etiologic association of Epstein-Barr virus with reactive hemophagocytic syndrome in Hong Kong Chinese

The herpes group of viruses, particularly Epstein-Barr virus (EBV), has frequently been implicated in the causation of reactive hemophagocytic syndrome (RHS) in the Western populations. EBV has also been implicated in the rare fulminant form o f RHS occurring in Oriental children. However, our previous adult-predominant study indicated little clinical and serological evidence of EBV infection in patients with RHS in Hong Kong. In the present study, we further examined this issue using a more sensitive and specific technique for the demonstration of EBV, ie, in situ hybridization for EBV encoded RNA (EBER). The 43 Chinese patients studied were mostly adults with a mean age of 44 years, and a male to female ratio of 1.5:1. About two-thirds (28) of patients had associated malignant lymphoma at the time of diagnosis. Five patients had documented infection (typhoid fever 2; systemic candidiasis 1; adenovirus pneumonia 11 viral encephalitis 1), and two had systemic lupus erythematosus. EBER signals were detected in only 11 cases (25.6%). All positive cases were associated with malignant lymphoma, and the positive signals were exclusively localized to the lymphoma cells but not in the histiocytes. On comparing the results (11 of 28 cases positive; 39.3%) with our previous data on EBER-expression in malignant lymphomas in Hong Kong, no significant difference is observed in the frequency of EBV-positivity between the two groups of lymphomas. Thus, a definite pathogenetic link between EBV and lymphoma-associated RHS cannot be established. However, the overrepresentation of T and T/NK lineage lymphoma in this sample of lymphoma- associated with RHS (61%) versus nonselected cases of lymphomas (31%) suggests that it is the T anti T/NK cell origin of the lymphoma rather than the EBV positivity that predisposes to RHS. Notwithstanding the previous findings, EBER in situ hybridization may still serve as a useful adjunct in the investigation of patients with RHS, because the presence of EBER-positive cells should raise a strong suspicion of an underlying malignant lymphoma.