Epstein-Barr virus, a ubiquitous human herpesvirus, can induce both lytic and latent infections that result in a variety of human diseases, including lymphoproliferative disorders. The oncogenic potential of Epstein-Barr virus is related to its ability to infect and transform B lymphocytes into continuously proliferating lymphoblastoid cells. However, Epstein-Barr virus has also been implicated in the development of T/natural killer cell lymphoproliferative diseases. Epstein-Barr virus encodes a series of products that mimic several growth, transcription and anti-apoptotic factors, thus usurping control of pathways that regulate diverse homeostatic cellular functions and the microenvironment. However, the exact mechanism by which Epstein-Barr virus promotes oncogenesis and inflammatory lesion development remains unclear. Epstein-Barr virus-associated T/natural killer cell lymphoproliferative diseases often have overlapping clinical symptoms as well as histologic and immunophenotypic features because both lymphoid cell types derive from a common precursor. Accurate classification of Epstein-Barr virus-associated T/natural killer cell lymphoproliferative diseases is a prerequisite for appropriate clinical management. Currently, the treatment of most T/natural killer cell lymphoproliferative diseases is less than satisfactory. Novel and targeted therapies are strongly required to satisfy clinical demands. This review describes our current knowledge of the genetics, oncogenesis, biology, diagnosis and treatment of Epstein-Barr virus-associated T/natural killer cell lymphoproliferative diseases.
Cell Transformation, Viral ; Epstein-Barr Virus Infections/*complications ; Herpesvirus 4, Human/*physiology ; Humans ; Killer Cells, Natural/immunology/metabolism/*pathology/*virology ; Lymphoproliferative Disorders/diagnosis/*etiology/therapy ; T-Lymphocytes/immunology/metabolism/*pathology/*virology

The World Health Organization (WHO) recently defined systemic Epstein-Barr virus (EBV)-positive T-cell lymphoproliferative disorders (LPD) of childhood as a life-threatening illness. However, this rare disease has not been extensively studied. Here we report a case of systemic EBV-positive T-cell LPD in a previously healthy middle-aged man with a chief complaint of chronic diarrhea. The initial colon biopsy showed focal infiltration of EBV-positive small lymphocytes without any atypia. However, the disease rapidly progressed and the patient required a total colectomy due to severe gastrointestinal bleeding. Three and half months after admission, the patient died from a complication of disseminated intravascular coagulation. The resected colon showed diffuse infiltration of EBV-positive atypical lymphocytes with ischemic change. Most atypical lymphocytes were CD3+ or CD5+. The monoclonality of EBV was demonstrated by sequence variation analysis of the latent membrane protein 1 (LMP1) gene in the colectomy specimen as well as in the initial biopsy.
Chronic Disease ; Colonoscopy ; Diarrhea/*diagnosis ; Disseminated Intravascular Coagulation/diagnosis ; Epstein-Barr Virus Infections/complications/virology ; Feces/virology ; Gastrointestinal Hemorrhage ; Herpesvirus 4, Human/genetics/*isolation & purification ; Humans ; Lymphoproliferative Disorders/*diagnosis/immunology/virology ; Male ; Middle Aged ; RNA, Viral/analysis ; T-Lymphocytes/*immunology/pathology