Systemic Epstein-Barr Virus-positive T-cell Lymphoproliferative Disease of Childhood Saranya Buppajarntham , Jindarat Tongtham 1 and

Systemic Epstein-Barr virus-positive (EBV+) T-cell lymphoproliferative disease of childhood is a very rare lymphoma subtype. The majority of patients were reported from Asian countries, especially Japan and Taiwan, strongly suggesting the racial predisposition, while there has been no reported case from Thailand. EBV is a well-known oncogenic herpesvirus, mostly targeting B cells. However, T cells are also the main target of EBV-associated monoclonal T-cell proliferation, which is the distinct characteristic of this fatal entity. Its clinical course demonstrates a rapid progression with severe pancytopenia, fulminant multi-organ failure, and subsequent death, usually within days to weeks. Consequently, prompt diagnosis and treatment is crucial. Case report: A 15-year-old girl presented with high-grade fever and sore throat for 2 weeks. She had marked hepatosplenomegaly and pancytopenia. Bone marrow study was performed and revealed abnormal lymphoid cells expressing CD3, CD8, EBV-encoded RNA (EBER), and monoclonal rearrangement of T-cell receptor (TCR) genes. Unfortunately, she did not respond to multi-modality treatment comprising monoclonal antibody to CD52, chemotherapy, and antiviral drugs, and subsequently died 1 month after diagnosis.


Introduction
Epstein-Barr virus (EBV) is a member of herpesvirus family, which infects more than 90% of people worldwide.Most infected children are asymptomatic, while affected adolescents may present with acute infectious mononucleosis and recover spontaneously within a few weeks.The minority of EBV-infected patients may manifest as chronic active EBV infection (CAEBV), characterized by the presence of these following features: persistent severe illness more than six months; evidence of organ involvement such as pneumonitis, hepatitis or bone marrow hypoplasia; and detection of EBV antigens or DNA in tissue. 1,2Generally, EBV infects B-cells using CD21 and major-histocompatibility-complex (MHC) class II on B-cell surface as a receptor and a cofactor, respectively.In most cases, EBV-infected B-cells are mainly eliminated by cytotoxic T-lymphocytes (CTLs) and natural killer (NK) cells, while remaining infected B-cells persist in the resting stage. 1,3The virus, however, can infect T-cells, NK-cells or epithelial cells.Therefore, it plays an important role in development of several malignancies, including nasopharyngeal carcinoma as well as lymphoproliferative diseases (LPDs), such as Burkitt's lymphoma, Hodgkin's disease and NK/T-cell lymphoma.

Casereport
A 15-year-old previously healthy girl had protracted high-grade fever and sore throat for 2 weeks.She had been admitted and received broad-spectrum antibiotics.However, she developed pancytopenia with rapidly deteriorating clinical symptoms.She was subsequently referred to King Chulalongkorn Memorial Hospital.The patient denied previous hematologic abnormalities and medical history suggesting immunodeficient status.Physical examination showed injected pharynx, enlarged tonsils, oral candidiasis, hepatosplenomegaly and small multiple lymph nodes ranging from 0.8-1 cm at right cervical region.Initial laboratory tests demonstrated pancytopenia and abnormal liver function tests: Hb 9.9 g/dL, WBC 0.47 x10 9 /L, neutrophils 0.17 x10 9 /L, lymphocytes 0.17 x10 9  Computer tomographic (CT) scan of abdomen showed hepatosplenomegaly without space-taking lesions and subcentimeter lymph nodes at gastrohepatic and paraaortic areas.CT scan of chest showed multiple small ground glass nodules in both lower lungs.
Bone marrow study was performed and revealed hypercellular trilineage marrow with prominent histiocytes with increased erythrophagocytosis (Figure 1).Immunohistochemistry study demonstrated abnormal T-cells that were positive for CD3, CD8, TIA1, Granzyme B and BF1, but negative for CD5, CD56, CD30 and CD20.In situ hybridization (ISH) using oligonucleotide probe complementary to EBV-encoded RNA (EBER) yielded the positive result.nearly all patients were Asian and Native American, while this entity was rarely found in western ethnic origin.Although some genetic defects in CTLs were proposed, no candidate genes have been identified. 2,4ts clinical course is extremely aggressive, with a median survival of less than 1 year.Patients usually develop hepatosplenomegaly and liver failure within a period of weeks and rapidly progress to multi-organ failure, coagulopathy, sepsis and death.Laboratory tests usually demonstrate profound pancytopenia and abnormal liver function tests.Rare patients manifest a subacute course of several months to a year progression. 2he histologic examination usually demonstrates infiltrating small lymphoid cells without significant cytologic atypia.However, cases with pleomorphic medium to large-sized lymphoid cells with striking morphologic atypia have been reported.Pathological findings of liver and spleen demonstrate mild to marked sinusoidal infiltration of lymphoid cells, accompanying by striking hemophagocytosis.The splenic white pulp is usually depleted.The liver has prominent portal and sinusoidal infiltration, cholestasis, steatosis and necrosis.The architecture of lymph nodes is usually preserved with variable degree of histiocytosis and erythrophagocytosis.Bone marrow biopsy shows histiocytic hyperplasia with prominent erythrophagocytosis.The most typical phenotype of the neoplastic cells by immunohistochemistry technique is CD2+, CD3+, CD56-and TIA1+.The CD8 is usually positive in cases secondary to acute primary EBV infection, while CD4 is positive in the setting of severe CAEBV.Rare cases show double positive of CD4 and CD8.EBER is mandatorily positive, and TCR gene rearrangement shows monoclonality. 5mportantly, the diagnosis must be differentiated from other NK/T-cell LPDs, which may present with hepatosplenic lymphoma, accompanying by hemophagocytosis and rapid multi-organ failure.The immunophenotypic and genetic features for differential diagnosis are summarized in table 1.
There has been no established standard treatment

Table1
However, the major obstacle to this therapy is graft-versus-host disease (GVHD) due to HLA incompatibility between donors and patients.Wang, et al. reported that using maternal lymphocytes could lower GVHD due to fetomaternal microchimerism leading to immunologic tolerance.They reported that 5 patients with systemic EBV+ T-cell LPD of childhood who received mother's lymphocyte infusion had significantly improved outcome without GVHD. 9ovel therapies are being developed to target EBV proteins.The expressed EBV antigens, which have roles in development and potentiation of lymphoproliferation, particularly latent membrane protein 1 (LMP1), LMP2 and Epstein-Barr virus nuclear antigen 1 (EBNA-1), might be the effective immunotherapeutic targets. 10In the future, the inhibition of molecular pathways in EBVinfected cell is the candidate for cure of this extremely aggressive disease. 2 Figure1Phagocytosis of red cells and platelets (arrow) by an activated histiocyte and an atypical large lymphoid cell (arrow head).