Acute thrombocytopenic purpura associated with primary Epstein-Barr virus infection.

Acute idiopathic thrombocytopenic purpura (ITP) often appears to be related to the sensitization by some viral infections. However, the causative viral agents are not identified in most cases. Although the primary infection with Epstein-Barr virus (EBV) occurs during early childhood in Japan, the majority of cases are usually asymptomatic. A minority are associated with acute infectious mononucleosis (IM), which is characterized by fever, tonsillitis, lymphadenopathy, splenomegaly and liver dysfunction. In this report, three cases are described of children with EBV-induced ITP who clinically had atypical findings of IM. Their primary EBV infections were confirmed by serological test and, in addition, were verified by the enhanced expression of activation antigens (HLA-DR and CD45RO) on T cells as well as the inverted ratio of CD4+ to CD8+ subsets. These observations imply that ITP can occur as one of the host responses during primary EBV infections, irrespective of clinical manifestations. Evaluation of lymphocyte subpopulations may be useful for the assessment of primary EBV infection in ITP.