Haemophagocytic lymphohistiocytosis and Epstein–Barr virus: a complex relationship with diverse origins,expression and outcomes

Epstein–Barr virus (EBV) is a ubiquitous herpesvirus with rare but severe potential for lymphoproliferative complications. EBV is associated with a variety of presentations of haemophagocytic lymphohistiocytosis (HLH). HLH is a life-threatening hyperinflammatory syndrome that can occur in patients with genetic defects associated with dysregulation of the immune response (familial HLH) or arise in patients with underlying infection or malignancy (non-familial or secondary HLH). EBV can both serve as the incidental trigger of familial HLH or as the driving factor in patients with selective inherited vulnerability (e.g. X-linked lymphoproliferative disease). Alternatively, acute infection can idiosyncratically cause non-neoplastic HLH in patients without inherited predisposition (i.e. secondary HLH), while EBV-associated T/natural killer (NK)-cell lymphoproliferative disorders and lymphomas can cause neoplasia-associated HLH. The present review will discern between EBV-associated familial and non-familial HLH and highlight diagnostic and therapeutic considerations. Non-familial EBV-associated HLH is a major diagnostic dilemma, as it represents a diverse spectrum of disease ranging from highly curable (non-neoplastic EBV-HLH) to indolent but incurable (chronic active EBV) to acutely fatal (systemic EBV-positive T-cell lymphoma of childhood). Increased clinical awareness and understanding of this rare and potentially devastating subset of EBV-related complications is desperately needed to improve survival for patients with neoplasia-associated HLH.     

儿童慢性活动性EB病毒感染合并UNC13D基因突变3例临床分析

目的探讨儿童慢性活动性EB病毒感染(CAEBV)合并UNC13D基因突变的临床特点,为临床诊治提供思路。方法对北京儿童医院血液肿瘤中心收治的3例CAEBV患儿进行基因突变筛查,对临床病例资料进行回顾性总结分析。结果3例患儿均存在UNC13D杂合子突变,但突变位点不同。例1和例2给予抗病毒治疗后好转出院,院外分别随访38个月和26个月,期间均出现EB病毒活动表现。例3行异基因造血干细胞移植术,随访34个月,仍无病生存。结论儿童CAEBV可能存在UNC13D基因突变,该突变可能为CAEBV发病机制以及预后差的重要原因之一。小年龄起病的发热、肝脾淋巴结肿大患儿,若EBV-DNA持续高滴度,建议尽早进行UNC13D基因突变的筛查。CAEBV患儿单纯抗病毒治疗效果差,异基因造血干细胞移植是根治性治疗手段。     

Atypische Epstein-Barr-Virus(EBV)-Infektionen im Kindes- und Jugendalter

The clinical syndrome of acute infectious mononucleosis is predominantly a disease of older children and adolescents. Primary EBV infection in younger infants is often subclinical. Complications may affect any organ system and are usually mild. In the majority of cases acute infectious mononucleosis has an excellent prognosis. Severly immuncompromised children and adolescents (i. e. under immunosuppressive therapy, after stem cell transplantation) may develop EBV⁺ B-cell lymphoproliferative disorders and malignant B-cell lymphoma. In this review, mainly the following forms of atypical EBV infections are described in detail: Fulminant, mostly fatal acute infectious mononucleosis following primary EBV infection may occur 1) sporadically (approx. 1 per 3000 cases of acute infectious mononucleosis), 2) in aprox. 60% of boys with X-linked lymphoproliferative disease (XLP), and 3) in very rare cases of a fulminant EBV+ T-cell lymphoproliferative disorder. No efficient therapy exists so far. Early allogeneic stem cell transplantation in boys with XLP may prevent fatal acute infectious mononucleosis and other complications. Chronic active EBV (CAEBV) infection is characterized by recurrent clinical episodes of severe infectious mononucleosis over months or years and additional unusual clinical signs and complications such as coronary artery aneurisms, hypersensitivity to mosquito bites and hydroa vacciniforme, as well as an markedly increased risk for malignant lymphoma, mostly of a T-cell type. In general, prognosis of CAEBV infection is poor. Allogeneic stem cell transplantation may lead to clinical remission. EBV-associated hemophagocytic syndrome may occur as an independent disorder [EBV-related hemophagocytic lymphhistiocytosis (EBV-HLH)] or as a serious complication of fatal infectious mononucleosis or CAEBV infection. Early treatment with etoposide, cyclosporine A and corticosteroids may improve the otherwise poor prognosis. The pathogenesis of atypical EBV infections is not known in most cases. Further molecular and immunologic studies may help to characterize these severe disorders and to develop more specific and more efficient therapies.     

Vascular lesion in a patient of chronic active Epstein-Barr virus infection with hypersensitivity to mosquito bites: vasculitis induced by mosquito bite with the infiltration of nonneoplastic Epstein-Barr virus-positive cells and subsequent development of natural killer/T-cell lymphoma with angiodestruction

This report describes a vasculitis and subsequently developing angiodestructive lymphoma in an 11-year-old Japanese-Filipino girl exhibiting mosquito allergy with the background of chronic active Epstein-Barr virus (EBV) infection. She developed necrotic skin ulcer at the site of mosquito bite, and histopathological examination revealed EBV-positive mononuclear cell infiltration throughout the wall of small-sized muscular artery. These EBV-positive lymphoid cells were oligoclonal in Southern blot analysis for EBV terminal repeats. Effectiveness of steroid therapy also supports the nonneoplastic nature. Approximately 1 year later, she developed progressive large skin ulcer without mosquito bites. Microscopically, the angiocentric or angiodestructive pattern of EBV-positive atypical cells supported the diagnosis of extranodal natural killer/T-cell lymphoma. Southern blot analysis revealed the monoclonal neoplastic nature of EBV-positive cells. In contrast to the primary mosquito bite lesion, natural killer/T-cell lymphoma cells exhibited the higher expression of EBV latent membrane protein 1 mRNA and the apparent protein expression detected by immunohistochemistry.     

A heart breaking case of rapidly developing severe hemophagocytic syndrome secondary to chronic active EBV infection; a case report and review of the literature

Epstein–Barr virus (EBV, HHV-4) is a gamma Herpesvirus with a 90% >seroprevalence in adults. Reactivations in non-immuno compromised individuals usually cause mild or no symptoms at all. Rarely, host immunity-virus balance is interrupted, resulting in a chronic active EBV infection. The following case illustrates the rapid development of severe hemophagocytic syndrome during chronic active EBV infection in a 73 year old woman who presented with lower extremity pain and edema, splenomegaly and abnormal liver enzymes. A diagnosis of chronic active EBV infection was made following an extensive investigation and the patient died secondary to rapidly progressive hemophagocytic syndrome.     

Development of Langerhans cell histiocytosis associated with chronic active Epstein-Barr virus infection

Chronic active Epstein-Barr virus (CAEBV) infection is characterized by a status of lymphoproliferative disease of EBV-infected cells, resulting in chronic or recurrent infectious mononucleosis-like symptoms. CAEBV is always accompanied by life-threatening complications. We report the case of a 2-year-old female patient with CAEBV who subsequently developed Langerhans cell histiocytosis (LCH) presenting with bilateral exophthalmos, bone, and skin involvement. In situ hybridization for EBER revealed EBV-infected B-cells present in lesional tissue implying that interactions between EBV-infected B-cells and lesional Langerhans cells may be associated with the development of LCH.     

Hypersensitivity to mosquito bites: A versatile Epstein–Barr virus disease with allergy,inflammation, and malignancy

Hypersensitivity to mosquito bites (HMB) is a rare disease characterized by transient intense skin reaction and systemic inflammation. Clinical presentation of HMB resembles other mosquito allergic responses, and it can also be difficult to clinically distinguish HMB from other severe allergic reactions. However, a distinctive pathophysiology underlies HMB.HMB belongs to a category of Epstein–Barr virus (EBV)-associated natural killer (NK) cell lymphoproliferative disorders (LPD). Hence, HMB may progress to systemic diseases, such as hemophagocytic lymphohistiocytosis, chronic active EBV disease, and EBV-associated malignancies.A triad of elevated serum IgE, NK lymphocytosis, and detection of EBV DNA in peripheral blood is commonly observed, and identification of EBV-infected NK cells usually facilitates the diagnosis. However, the effective treatment is limited, and its precise etiology remains unknown.Local CD4+ T cell proliferation triggered by mosquito bites appears to help induce EBV reactivation and EBV-infected NK-cell proliferation. These immunological interactions may explain the transient HMB signs and symptoms and the disease progression toward malignant LPD.Further research to elucidate the mechanism of HMB is warranted for better diagnosis and treatment of HMB and other forms of EBV-associated LPD.     

Successful control of Epstein-Barr virus (EBV)-infected cells by allogeneic nonmyeloablative stem cell transplantation in a patient with the lethal form of chronic active EBV infection

Chronic active Epstein-Barr virus infection (CAEBV) is a heterogeneous EBV-related disorder, ranging from mild/moderate forms to rapidly lethal disorders. The lethal form of CAEBV is characterized by multiple organ failure, hemophagocytic syndrome, and development of lymphomas. Allogeneic stem cell transplantation is considered as the only potentially curative treatment for the lethal form of CAEBV, but it is not always desirable because of the high incidence of regimen-related toxicities. A 17-year-old female with CAEBV, who was refractory to conventional therapies and considered to be unable to receive a myeloablative regimen because of multiple organ dysfunction, underwent allogeneic nonmyeloablative stem cell transplantation (allo-NST) before developing a hematological malignancy. She has been well without any signs of CAEBV for 27 months after allo-NST, and we confirmed that specific cytotoxic T lymphocyte activity against EBV was reconstituted. This outcome suggests that allo-NST can control CAEBV by reconstituting the host immunity against EBV.     

Transcriptional profiling of Epstein-Barr virus (EBV) genes and host cellular genes in nasal NK/T-cell lymphoma and chronic active EBV infection

Nasal NK/T-cell lymphoma is an aggressive subtype of non-Hodgkin lymphoma (NHL) that is closely associated with Epstein-Barr virus (EBV). The clonal expansion of EBV-infected NK or T cells is also seen in patients with chronic active EBV (CAEBV) infection, suggesting that two diseases might share a partially similar mechanism by which EBV affects host cellular gene expression. To understand the pathogenesis of EBV-associated NK/T-cell lymphoproliferative disorders (LPD) and design new therapies, we employed a novel EBV DNA microarray to compare patterns of EBV expression in six cell lines established from EBV-associated NK/T-cell LPD. We found that expression of BZLF1, which encodes the immediate-early gene product Zta, was expressed in SNK/T cells and the expression levels were preferentially high in cell lines from CAEBV infection. We also analyzed the gene expression patterns of host cellular genes using a human oligonucleotide DNA microarray. We identified a subset of pathogenically and clinically relevant host cellular genes, including TNFRSF10D, CDK2, HSPCA, IL12A as a common molecular biological properties of EBV-associated NK/T-cell LPD and a subset of genes, such as PDCD4 as a putative contributor for disease progression. This study describes a novel approach from the aspects of viral and host gene expression, which could identify novel therapeutic targets in EBV-associated NK/T-cell LPD.     

Extranodal type T/NK-cell lymphoma with an atypical clinical presentation

Peripheral-type natural killer (NK)-or T-cell lymphomas are rare disorders characterized with clonal proliferation of mature lymphocytes. They have been linked to chronic and active Epstein-Barr virus infection (CAEBV), which itself is not defined as a malignant hematological disorder. The authors present a patient with T/NK-cell lymphoma involving skin, kidneys, spleen, pancreas, and meninges. She was remarkable for having the mosaic feature of more than one type of extranodal T/NK-cell lymphoma. She also had mixed findings of CAEBV that might have been attributed both to hypersensitivity to mosquito bites and to hemophagocytic lymphohistiocytosis.