[Chronic active Epstein-Barr virus disease: current understanding of its pathogenesis, diagnosis, and treatment]

Chronic active Epstein-Barr virus disease (CAEBV) is a rare and intractable disorder characterized by persistent or recurrent inflammation associated with persistent EBV infection of T or NK cells and their clonal proliferation. In the revised fourth edition of the WHO classification, CAEBV was classified as an EBV-positive T- and NK-cell neoplasm, which greatly raised global awareness and recognition of this disease. Accurate diagnosis requires identification of the EBV-infected cell population. In addition to pathological evaluation and detection of EBV genomes in individual lymphocyte subsets by PCR, the introduction of EBER-flow FISH using flow cytometry is expected to provide more efficient diagnostic options. Today, allogeneic hematopoietic stem cell transplantation is the only established curative treatment. However, recent advances in the understanding of the molecular pathogenesis of CAEBV have led to the identification of novel therapeutic candidates tailored to the disease biology, such as JAK inhibitors. The pathogenesis of CAEBV is also being progressively elucidated. The absence of a CAEBV-specific viral strain suggests the involvement of host factors in disease development. In recent years, cases have been reported from various regions of the world, and further progress through international collaborative research is anticipated.