Hydroa vacciniforme-like lymphoproliferative disorder: an EBV disease with a low risk of systemic illness in whites

Hydroa vacciniforme lymphoproliferative disorder, a clinicopathologic and genetic analysis

Hydroa vacciniforme lymphoproliferative disorder (HV-LPD) is a rare Epstein-Barr virus (EBV)-associated disease and the systemic form shows a propensity to progress and some cases may eventually develop a disease simulating NK/T-cell lymphoma or even aggressive NK-cell leukemia. We report 12 patients with systemic HV-LPD of median age 15.8 years with dermatosis involving the face, trunk, extremities and serous membranes. Ten of 12 patients (83 %) had systemic symptoms including 9 with prominent facial edema and 2 with bone marrow involvement. All cases were positive for EBER and CD3 and lacked CD20. Additional positive markers included CD8 in 11 of 12 (91.6 %), CD56 in 1 of 12 (8.3 %), granzyme B in 6 of 7 (85.7 %), TIA1 in 2 of 2 (100 %) and CD30 in 1 of 3 (33.3 %). Two cases studied demonstrated monoclonal TCR-γ and one also had TCR-β rearrangements. Five cases were sequenced and showed recurrent mutations in ALMS1, ALPK2, BCORL1, KANK2, KMT2D, NCOR1, PTPRD, RHOA, TNIK, TP53 and ZFHX3, and single cases showed a variety of mutations including BCOR, CREBBP, DDX3X, DMXL2, IRF4, IRF8, KDM6A, MGA, NCOR2, PLCG1, PRDM1, RNF213, SMARCA4, STAT5B and TET2 mutation. Most patients were treated with immunomodulating therapy, two received methotrexate, three received multiagent chemotherapy and one underwent hematopoietic stem cell transplant. Follow-up was available in 10 patients of whom 6 died of disease and one was alive without disease. Our results showed that patients with persistent/progressive systemic HV-LPD have a poor prognosis and did not respond well to chemotherapy. The mutation spectrum bore some resemblance to extranodal NK/T lymphomas but also had notable differences.

The fifth edition of the WHO classification of mature T cell, NK cell and stroma-derived neoplasms

The fifth edition of the WHO Classification of Haematolymphoid Tumors (WHO-HAEM5) introduces significant advancements in the understanding and diagnosis of mature T cell and NK cell, and stroma-derived neoplasms, and incorporates molecular and genetic data/findings accrued over the past years. The classification has been reorganised using a hierarchical system, employed across the fifth edition of the WHO classification of tumours of all organ systems. This review highlights recent developments, evolving concepts, and key updates since the revised fourth edition (WHO-HAEM4R). It enumerates the minimal/essential criteria necessary for diagnosis and classification, constituting not only the importance of clonality analysis in the workup of certain T cell neoplasms and the detection of infectious agents and specific genetic alterations in a subset of entities but also the applicability of these criteria in resource-constrained settings. 'Stroma-derived neoplasms of lymphoid tissues discussed in this review is a new category introduced in HAEM5 that encompasses mesenchymal tumours occurring exclusively in lymph nodes and spleen and mesenchymal dendritic cell neoplasms previously classified as 'histiocytic/dendritic cell neoplasms'.

Pediatric Cutaneous T-Cell Neoplasms: Clinical and Pathological Features, Updated Classifications, and Critical Differential Diagnoses

Cutaneous T-cell lymphoid neoplasms in childhood are exceedingly rare, presenting with a wide spectrum of clinical presentation and outcomes. Due to numerous clinical and pathological mimics, an integrated evaluation of clinical, histopathological, immunohistochemical, and molecular findings is critical for a diagnosis. Here, we review the clinical and pathological features, updated classifications, and critical differential diagnoses of cutaneous T-cell lymphoid neoplasms in children.

Pediatric lymphomas: overview and diagnostic challenges

Only 10% of new lymphoma diagnoses in the USA occur in children < 15 years. Although the same diagnostic criteria apply to both adult and pediatric lymphomas, there are important differences in some lymphoma subtypes. These differences are recognized by the World Health Organization (WHO) with the recent 2022 classification of pediatric tumors including pediatric hematopoietic tumors. Here, we review the WHO classification scheme for pediatric lymphomas and summarize the diagnostic criteria, recent genetic findings, and differences from their adult counterparts for some subtypes including those yet to be included as a definitive subtype. In general, there are differences in relatively frequency, genetic mutation, and prognosis with the pediatric counterpart often having better prognosis. Emerging B-cell lymphomas with recurrent gene alterations such as IRF4 rearrangement and 11q gain/loss chromosomal alterations will be reviewed. The overlapping pathological, clinical, and molecular features between pediatric-type follicular lymphoma (PTFL) and pediatric nodal marginal zone lymphoma (PNMZL) suggesting one disease with broad morphological spectrum will be discussed. The pathogenetic role of EBV in subclassifying Burkitt lymphoma is highlighted. The revised classification of the EBV-positive lymphoproliferative disorders in children is discussed. This review will focus on novel findings, areas of special interest, and diagnostic challenges in pediatric lymphomas.

From the midfacial destructive drama to the unfolding EBV story: a short history of EBV-positive NK-cell and T-cell lymphoproliferative diseases

Epstein-Barr virus (EBV) is a ubiquitous gammaherpesvirus that has been related to oncogenesis of lymphoid and epithelial malignancies. Although the mechanism of EBV infection of NK and T cells remains enigmatic, it plays a pathogenic role in various EBV+ NK-cell and T-cell lymphoproliferative diseases (LPDs), through promotion of cell activation pathways, inhibition of cell apoptotic pathways, behaving as oncogenes, interacting with host oncogenes or acting epigenetically. The study of NK-cell LPDs, previously hampered by the lack of immunophenotypical and genotypical criteria of NK cells, has become feasible with the recently accepted criteria. EBV+ NK- and T-cell LPDs are mostly of poor prognosis. This review delivers a short history from primeval to recent EBV+ NK- and T-cell LPDs in non-immunocompromised subjects, coupled with increasing interest, and work on the biological and oncogenic roles of EBV.

The fifth edition of the WHO-Classification - what is new for cutaneous lymphomas?

The recently published 5th edition of the "World Health Organization classification of hematolymphoid tumors: lymphoid neoplasms" provides a hierarchical reorganization. In general, new (definitive) entities as well as tumor-like lesions were included. Primary cutaneous B-cell lymphomas (CBCL) received a thorough review. A new class/family of cutaneous follicle center lymphomas was defined. Primary cutaneous marginal zone lymphoma is now presented as a separate entity independent from extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue. In primary cutaneous T-cell lymphoma, former provisional entities were upgraded to definite entities. Sézary Syndrome was sorted into the class/family of mature T-cell and NK-cell leukemias. Additionally, a newly formed entity of primary cutaneous peripheral T-cell lymphoma, NOS was created for CTCL entities that do not fit into the already described CTCL entities. The increasing importance of genomic and molecular data has already been recognized in classifying leukemias and systemic lymphomas. However, in PCL the genomic landscape has not yet been fully described and validated. Therefore, future research is necessary to describe the genomic and molecular mechanisms underlying the disease entities more clearly. This would both meet a diagnostic need and valuably contribute to future classification schemes.

A Fatal Case of Severe Leg Edema and Necrotic Ulcers in a 14-Year-Old Boy

A 14-year-old boy presented with edema, ulcers, tenderness, and progressive functional limitation of both legs, first diagnosed as Henoch-Schonlein vasculitis. Then, he underwent one inguinal lymph node excision and two skin biopsies which reported an angiocentric lymphoproliferative process, EBER (Epstein-Barr virus-encoded small RNA) positive, consistent with hydroa vacciniforme-like lymphoproliferative disorder (HVLPD); after eight weeks, his face presented with edema and ulcers, characteristic of the original patients described with HVLPD. The patient's parents refused treatment and took him back home, and he died a few months later. Our case study highlights an atypical localization of the disease, as it initially presented in the lower extremities rather than the face, posing a diagnostic challenge that was ultimately resolved through biopsy.

Fifth Edition of the World Health Organization Classification of Tumors of the Hematopoietic and Lymphoid Tissues: Mature T-Cell, NK-Cell, and Stroma-Derived Neoplasms of Lymphoid Tissues

This review focuses on mature T cells, natural killer (NK) cells, and stroma-derived neoplasms in the fifth edition of the World Health Organization classification of hematolymphoid tumors, including changes from the revised fourth edition. Overall, information has expanded, primarily due to advancements in genomic understanding. The updated classification adopts a hierarchical format. The updated classification relies on a multidisciplinary approach, incorporating insights from a diverse group of pathologists, clinicians, and geneticists. Indolent NK-cell lymphoproliferative disorder of the gastrointestinal tract, Epstein-Barr virus-positive nodal T- and NK-cell lymphoma, and several stroma-derived neoplasms of lymphoid tissues have been newly introduced or included. The review also provides guidance on how the fifth edition of the World Health Organization classification of hematolymphoid tumors can be applied in routine clinical practice.

EBV-Related Lymphoproliferative Diseases: A Review in Light of New Classifications

Epstein-Barr virus (EBV) is a prevalent virus that can be detected in the vast majority of the population. Most people are asymptomatic and remain chronically infected throughout their lifetimes. However, in some populations, EBV has been linked to a variety of B-cell lymphoproliferative disorders (LPDs), such as Burkitt lymphoma, classic Hodgkin lymphoma, and other LPDs. T-cell LPDs have been linked to EBV in part of peripheral T-cell lymphomas, angioimmunoblastic T-cell lymphomas, extranodal nasal natural killer/T-cell lymphomas, and other uncommon histotypes. This article summarizes the current evidence for EBV-associated LPDs in light of the upcoming World Health Organization classification and the 2022 ICC classification.

The 5th edition of the World Health Organization Classification of mature lymphoid and stromal tumors - an overview and update

The purpose of this review is to give an overview on the conceptual framework and major developments of the upcoming 5th edition of the World Health Organization (WHO) Classification of Haematolymphoid tumours (WHO-HAEM5) and to highlight the most significant changes made in WHO-HAEM5 compared with the revised 4th edition (WHO-HAEM4R) of lymphoid and stromal neoplasms. The changes from the revised 4th edition include the reorganization of entities by means of a hierarchical system that is realized throughout the 5th edition of the WHO classification of tumors of all organ systems, a modification of nomenclature for some entities, the refinement of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities. For the first time, tumor-like lesions, mesenchymal lesions specific to lymph node and spleen, and germline predisposition syndromes associated with the lymphoid neoplasms are included in the classification.

A comparison of the International Consensus and 5th WHO classifications of T-cell lymphomas and histiocytic/dendritic cell tumours

Since the publication in 2017 of the revised 4th Edition of the World Health Organization (WHO) classification of haematolymphoid tumours, here referred to as WHO-HAEM4, significant clinicopathological, immunophenotypic and molecular advances have been made in the field of lymphomas, contributing to refining the diagnostic criteria of several diseases, upgrading entities previously defined as provisional and identifying new entities. This process has resulted in two recent classification proposals of lymphoid neoplasms: the International Consensus Classification (ICC) and the 5th edition of the WHO classification (WHO-HAEM5). In this paper, we review and compare the two classifications in terms of diagnostic criteria and entity definition, focusing on T-cell lymphomas and histiocytic/dendritic cell tumours. Moreover, we update the genetic data of the various pathological entities. The main goal is to provide a tool to facilitate the work of the pathologists, haematologists and researchers involved in the diagnosis and treatment of these haematological malignancies.

Hydroa Vacciniforme

This case report describes recurrent episodes of pruritic vesicular lesions and erosions on the face and photoexposed areas of the arms as well as multiple varioliform scars.

Chronic active Epstein-Barr virus and hydroa vacciniforme-like lymphoproliferative disorder in a pediatric patient complicated by fatal ruptured cerebral artery aneurysm

Hydroa vacciniforme-like lymphoproliferative disorder (HV-LPD) is a rare cutaneous form of chronic active Epstein-Barr virus (CAEBV) that presents with vesicular lesions induced by sun-exposure. Arterial aneurysm is a rare but potentially fatal complication of CAEBV and HV-LPD.

Clinicoprognostic Study of Hydroa Vacciniforme-like Lymphoproliferative Diseases: A Systematic Review

BACKGROUND

Limited clinicopathological and prognostic data are available on hydroa vacciniforme (HV)-like lymphoproliferative diseases (HVLPD).

METHODS

This systematic review searched HVLPD reports in Medline via PubMed, Embase, Cochrane, and CINAHL databases in October 2020.

RESULTS

A total of 393 patients (65 classic HV, 328 severe HV/HV-like T-cell lymphoma [HVLL]) were analyzed. Among severe HV/HVLL cases, 56.0% were Asians, whereas 3.1% were Caucasians. Facial edema, hypersensitivity to mosquito bites, the onset of skin lesion, and percentage of severe HV/HVLL differed significantly by race. Progression to systemic lymphoma was confirmed in 9.4% of HVLPD patients. Death occurred in 39.7% patients with severe HV/HVLL. Facial edema was the only risk factor associated with progression and overall survival. Mortality risk was higher in Latin Americans than in Asians and Caucasians. CD4/CD8 double-negativity was significantly associated with the worst prognosis and increased mortality.

CONCLUSION

HVLPD is a heterogeneous entity with variable clinicopathological features associated with genetic predispositions.

Coexpression of natural killer cell antigens by T-cell large granular lymphocytes in hydroa vacciniforme lymphoproliferative disorder and the involvement of Vδ1 + epithelial-type γδT cells

Hydroa vacciniforme lymphoproliferative disorder (HV-LPD) is a cutaneous variant of chronic active Epstein-Barr virus disease. We examined the coexpression of T- and natural killer (NK)-cell antigens in five patients with classic HV (cHV) and five with systemic HV (sHV). T-cell receptor (TCR) repertoire analysis was performed with high‑throughput sequencing. All five cHV patients had increased γδT cells (> 5%), whereas five sHV patients showed γδT- and αβT-cell dominance in two patients each, and a mixture of abnormal γδT and αβT cells in one. Circulating CD3 + T cells expressed CD16/CD56 at 7.8-42.3% and 1.1-9.7% in sHV and cHV, respectively. The percentage of CD16/CD56 + T cells was higher in the large granular lymphocyte or atypical T-cell fractions in sHV, but no TCR Vα24 invariant chain characteristic of NKT cells was detected. Considerable numbers of CD3 + cells expressing CD56 were observed in sHV skin infiltrates. Of the circulating γδT cells tested, TCR Vδ1 + cells characteristic of the epithelial type of γδT cells were dominant in two sHV cases. Thus, atypical αβT and γδT cells in HV-LPD can express NK-cell antigens, such as CD16 and CD56, and Vδ1 + epithelial-type γδT cells are a major cell type in some HV-LPD cases.

An update on viral-induced cutaneous lymphoproliferative disorders. CME Part I

Viral-induced cutaneous T-cell lymphomas are an uncommon group of lymphoproliferative disorders characterized by a viral infection of T and natural killer (NK) cells. This group of cutaneous T-cell lymphomas is more commonly encountered in Asians and Native Americans from Central and South America compared with Western populations. Viral-associated lymphoproliferative disorders include a spectrum of entities that range from nonneoplastic lesions, such as chronic active Epstein-Barr virus infection and infective dermatitis to malignant diseases, such as extranodal NK/T-cell lymphoma, hydroa vacciniforme-like T-cell lymphoma, and adult T-cell leukemia/lymphoma. This review article will focus on hydroa vacciniforme-like lymphoproliferative disorder, extranodal NK/T-cell lymphoma, adult T-cell leukemia/lymphoma, lymphomatoid granulomatosis, and Epstein-Barr virus-positive mucocutaneous ulcers. We will review the pathogenesis of these conditions and the challenges of making a timely diagnosis in early-stage disease and discuss the common clinicopathologic manifestations, mutational landscape, and approaches to treat these highly aggressive and frequently lethal types of lymphoma.

Diagnosis and management of cutaneous lymphomas and lymphoid proliferations in children, adolescents and young adults (CAYA)

Cutaneous lymphomas and lymphoid proliferations (LPD) in children, adolescents, and young adults (CAYA) are a heterogeneous group of lymphoid neoplasms that present formidable diagnostic challenges to clinicians and pathologists alike. Although rare overall, cutaneous lymphomas/LPD occur in real-world settings and awareness of the differential diagnosis, potential complications, and various therapeutic approaches will help ensure the optimal diagnostic work-up and clinical management. Lymphomas/LPD involving the skin can occur as primary cutaneous disease in a patient that characteristically has lymphoma/LPD confined to the skin, or as secondary involvement in patients with systemic disease. This review will comprehensively summarize both primary cutaneous lymphomas/LPD that occur in the CAYA population as well as those CAYA systemic lymphomas/LPD with propensity for secondary cutaneous involvement. Focus on the most common primary entities occurring in CAYA will include lymphomatoid papulosis, primary cutaneous anaplastic large cell lymphoma, mycosis fungoides, subcutaneous panniculitis-like T-cell lymphoma, and hydroa vacciniforme lymphoproliferative disorder.

Clinical and Pathological Features of Hydroa Vacciniforme-Like Lymphoproliferative Disorder Along with Risk Factors Indicating Poor Prognosis

Purpose

To examine the clinical and pathological features, laboratory markers, therapeutic options and risk factors indicating poor prognosis of hydroa vacciniforme-like lymphoproliferative disorder (HVLPD).

Patients and Methods

Seven patients with HVLPD had their clinical and pathological data collected. Immunohistochemical staining, Epstein-Barr virus-encoded RNA (EBER) in situ hybridization experiments, T-cell receptor (TCR) gene rearrangement, RT-PCR tests and the Elisa assay were carried out.

Results

The main clinical manifestations were papulovesicular lesions and ulcers on the face, neck, or trunk. Five cases had systemic symptoms. Three of the deceased patients had significant facial edema, deep body necrosis, and ulceration. The pathological results demonstrated that lymphocytes infiltrated blood vessels and sweat glands in addition to the dermis and subcutaneous tissues. All patients tested positive for CD3 and EBER. Six cases tested positive for TCRβF1, but none tested positive for TCRδ. TCRγ monoclonal rearrangement, strongly positive expression of TIA-1 and a Ki67 proliferation index of 40% occurred in 3 fatal cases. When compared to the survival group, the plasma EBV DNA in the deceased group was considerably higher (P<0.05). IFN-γ and TNF-α cytokine levels in patients were higher than in the control group, particularly in the deceased group (P<0.05). The skin lesions on all patients recovered quickly underwent conservative care. Nonetheless, 3 patients passed away as the disease progressed in its latter stages.

Conclusion

In our cases, the main infiltrating cells were T cells and the dominant lymphocyte subclass was αβT cells. A significant increase in lgE level, plasma EBV DNA, IFN-γ, and TNF-α cytokine levels, decreased hemoglobin level, strongly positive expression of TIA-1, high Ki67 proliferation index, and positive TCR gene rearrangement are all indicators of a poor prognosis.

New concepts in EBV-associated B, T, and NK cell lymphoproliferative disorders

EBV-associated lymphoproliferative disorders (LPD) include conditions of B, T, and NK cell derivation with a wide clinicopathological spectrum ranging from indolent, self-limiting, and localized conditions to highly aggressive lymphomas. Since the 2016 World Health Organization (WHO) lymphoma classification, progress has been made in understanding the biology of the EBV-associated LPDs. The diagnostic criteria of EBV+ mucocutaneous ulcer and lymphomatoid granulomatosis have been refined, and a new category of EBV-positive polymorphic B cell LPD was introduced to encompass the full spectrum of EBV-driven B cell disorders. The differential diagnosis of these conditions is challenging. This report will present criteria to assist the pathologist in diagnosis. Within the group of EBV-associated T and NK cell lymphomas, a new provisional entity is recognized, namely, primary nodal EBV+ T or NK cell lymphoma. The EBV + T and NK cell LPDs in children have undergone major revisions. In contrast to the 2016 WHO classification, now four major distinct groups are recognized: hydroa vacciniforme (HV) LPD, severe mosquito bite allergy, chronic active EBV (CAEBV) disease, and systemic EBV-positive T cell lymphoma of childhood. Two forms of HV LPD are recognized: the classic and the systemic forms with different epidemiology, clinical presentation, and prognosis. The subclassification of PTLD, not all of which are EBV-positive, remains unaltered from the 2016 WHO classification. This review article summarizes the conclusions and the recommendations of the Clinical Advisory Committee (CAC), which are summarized in the International Consensus Classification of Mature Lymphoid Neoplasms.

The International Consensus Classification of Mature Lymphoid Neoplasms: a report from the Clinical Advisory Committee

Since the publication of the Revised European-American Classification of Lymphoid Neoplasms in 1994, subsequent updates of the classification of lymphoid neoplasms have been generated through iterative international efforts to achieve broad consensus among hematopathologists, geneticists, molecular scientists, and clinicians. Significant progress has recently been made in the characterization of malignancies of the immune system, with many new insights provided by genomic studies. They have led to this proposal. We have followed the same process that was successfully used for the third and fourth editions of the World Health Organization Classification of Hematologic Neoplasms. The definition, recommended studies, and criteria for the diagnosis of many entities have been extensively refined. Some categories considered provisional have now been upgraded to definite entities. Terminology for some diseases has been revised to adapt nomenclature to the current knowledge of their biology, but these modifications have been restricted to well-justified situations. Major findings from recent genomic studies have impacted the conceptual framework and diagnostic criteria for many disease entities. These changes will have an impact on optimal clinical management. The conclusions of this work are summarized in this report as the proposed International Consensus Classification of mature lymphoid, histiocytic, and dendritic cell tumors.

Case report: Cellular therapy for hydroa vacciniforme-like lymphoproliferative disorder in pediatric common variable immunodeficiency with chronic active Epstein-Barr virus infection

Hydroa vacciniforme-like lymphoproliferative disorder (HV-LPD) is a cutaneous form of chronic active Epstein-Barrvirus (EBV) infection, which can develop into the extremely rare systemic lymphoma. Patients with Inborn errors of immunity (IEI), such as common variable immunodeficiency (CVID), are at higher risk of developing a severe course of infections especially viral and malignancies than the general population. The aim of the study was to present complex diagnostic and therapeutic management of HV-LPD. The clinical diagnosis was confirmed at the histological and molecular level with next generation sequencing. HV-LPD was diagnosed in a patient with CVID and chronic active Epstein–Barr virus (CAEBV) infection. The patient was refractory to CHOP chemotherapy and immunosuppressive treatment in combination with antiviral drugs (prednisone, bortezomib, gancyclovir). The third-party donor EBV-specific cytotoxic T cells (EBV-CTL, tabelecleucel) were used, which stabilised the disease course. Finally, matched unrelated donor hematopoietic cell transplantation (MUD-HCT) was performed followed by another cycle of EBV-CTL.

The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Lymphoid Neoplasms

We herein present an overview of the upcoming 5^th edition of the World Health Organization Classification of Haematolymphoid Tumours focussing on lymphoid neoplasms. Myeloid and histiocytic neoplasms will be presented in a separate accompanying article. Besides listing the entities of the classification, we highlight and explain changes from the revised 4^th edition. These include reorganization of entities by a hierarchical system as is adopted throughout the 5^th edition of the WHO classification of tumours of all organ systems, modification of nomenclature for some entities, revision of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities, as well as inclusion of tumour-like lesions, mesenchymal lesions specific to lymph node and spleen, and germline predisposition syndromes associated with the lymphoid neoplasms.

[EBV-associated lymphoproliferative disorders]

Epstein-Barr-virus-associated lymphoproliferations (EBV-LPD) constitute a wide spectrum from benign, self-limiting lymphoproliferations to malignant lymphoma. Because of the clinical and morphological heterogeneity of EBV-LPD and the high prevalence of EBV infections, knowledge of the diagnostic criteria is of great importance for the practice of diagnostic pathology. In this review, clinical and pathological characteristics of the non-malignant EBV-related LPD in patients with and without immunosuppression are presented and their current classification is discussed.EBV-LPD can be of B‑cell or T/NK-cell origin. Identification of EBV latency type and information about possible (iatrogenic) immunodeficiency of the patient are critical for diagnostic evaluation and separation from malignant lymphoma. The clinical context and the detection of EBV in T‑ and NK-cells are both essential for the diagnosis of EBV+ T/NK-cell LPD, which are rare in European countries.

Pediatric Cutaneous Hematologic Disorders: Cutaneous Lymphoma and Leukemia Cutis: Experience of a Tertiary-Care Pediatric Institution and Review of the Literature

BACKGROUND

Cutaneous hematologic malignancies are rare in children, and the literature about them is still sparse.

OBJECTIVE

The purpose of our study was to report our experience with pediatric cases of cutaneous hematologic disorders and describe their clinical and histological features.

METHODS

Data were retrospectively collected from the histopathologic database of the CHU Sainte-Justine, University of Montreal, Montreal, Canada. All patients up to 18 years of age with a diagnosis of a primary cutaneous lymphoma (including lymphomatoid papulosis), secondary cutaneous lymphoma or cutaneous manifestations of leukemia, followed from 1980 to 2019 at our center were reviewed.

RESULTS

Thirty-six patients were included. Age at presentation ranged from birth to 18 years of age (mean 7.83 ± 5.16; median 7.0). Ten different hematologic disorders were identified according to the WHO-EORTC classifications: lymphomatoid papulosis (10 cases), mycosis fungoides (6 cases), anaplastic large cell lymphoma (4 cases), pre-B acute lymphoid leukemia (5 cases), primary cutaneous marginal zone B-cell lymphoma (4 cases), primary cutaneous CD4⁺medium T-cell lymphoproliferative disorder (1 case), extranodal NK/T-cell lymphoma (1 case), hydroa vacciniforme-like lymphoproliferative disorder (1 case), B-cell lymphoblastic lymphoma (1 case) and acute myeloid leukemia (3 cases).

CONCLUSION

The most common subtype of cutaneous hematologic disease in our single institution study was lymphomatoid papulosis (type A and type C), followed by mycosis fungoides. Recognition of this large clinical and histological spectrum by dermatologists is important because diagnosis is often established by biopsy of skin lesions, even in secondary cutaneous cases. Moreover, the clinicopathological correlation is of utmost importance for the final diagnosis of those pathologies.

EBV associated T- and NK-cell lymphoproliferative diseases: A comprehensive overview of clinical manifestations and novel therapeutic insights

EBV is a ubiquitous virus that infects nearly all people around the world. Most infected people are asymptomatic and do not show serious sequelae, while others may develop Epstein-Barr virus (EBV)-positive T and NK-cell lymphoproliferations characterised by EBV-infected T or NK cells. These disorders are more common in Asian and Latin American people, suggesting genetic predisposition as a contributing factor. The revised WHO classification classifies the lymphoproliferative diseases as: extranodal NK/T-cell lymphoma nasal type (ENKTL), aggressive NK-cell leukemia (ANKL), primary EBV-positive nodal T or NK cell lymphoma (NNKTL), systemic EBV-positive T-cell lymphoproliferative disease of childhood (STCLC), systemic chronic active EBV infection (sys CAEBV), hydroa-vacciniforme (HV) and severe mosquito bite allergy (SMBA). Recent advances in the molecular pathogenesis of these diseases have led to the development of new therapeutic strategies. Due to the infrequency of the diseases and broad clinicopathological overlap, the diagnosis and classification are challenging for both clinicians and pathologists. In this article, we aim to review the recent pathological findings which can be helpful for designing new drugs, clinical presentations and differential diagnoses, and suggested therapeutic interventions to provide a better understanding of these rare disorders.

Skin diseases in Asian individuals that you do not want to miss: A selection of unique or relatively more common conditions in Asian populations

The Asian population currently constitutes a simple majority of the global population, comprising nearly 60%. The percentage of the US population that identifies as Asian is expected to grow to 41 million by the year 2050, making up an eventual 9% of the US population. As the world and US populations of Asian individuals increase, the demand for dermatologic care from this population will increase, requiring dermatologists to become more familiar with the diagnosis and treatment of Asian-specific skin characteristics and diseases. In this contribution, we review skin conditions specific to or relatively more common in Asian patients to help recognition and management of diseases in an increasing Asian patient population. We discuss prurigo pigmentosa, primary cutaneous plasmacytosis, lipodystrophia centrifugalis abdominalis infantilis, Epstein-Barr viru-positive T- and natural killer-cell lymphoproliferative disorders, acquired bilateral nevus of Ota-like macules, and Behҫet disease.

Hydroa Vacciniforme-Like Lymphoproliferative Disorder in an Adult Patient With Chronic Lymphocytic Leukemia

Hydroa vacciniforme-like lymphoproliferative disorder (HV-LPD) is a rare Epstein-Barr virus (EBV)-positive T-cell lymphoproliferative disorder (LPD) which primarily affects children from Latin America and Asia. Typical features include vesicles and ulceration in sun-exposed areas which may be accompanied by systemic symptoms such as fever, lymphadenopathy and hepatosplenomegaly. We report a 73-year-old man diagnosed with HV-LPD in the context of zanubrutinib (oral Bruton tyrosine kinase (BTK)-inhibitor) treatment for chronic lymphocytic leukemia (CLL). The patient presented with slowly progressive peri-orbital edema and erythema non-responsive to topical therapies which eventually progressed to focal crusting and erosion. Prednisolone was subsequently introduced, which led to a good response in the patient’s symptoms.

Epstein-Barr Virus-Associated T- and NK-Cell Lymphoproliferative Diseases: A Review of Clinical and Pathological Features

Simple Summary

In most Epstein–Barr virus (EBV)-infected individuals, the virus establishes a lifelong latent infection with no specific clinical manifestation. However, EBV primary infection and secondary reactivation may cause various EBV-associated lymphoproliferative disorders (LPD), including hematologic malignancies. Among them, EBV-positive T/NK LPD are uncommon diseases defined by the proliferation of T- or NK-cells infected by EBV, more commonly encountered in Asians and Latin Americans. They encompass a spectrum of disorders ranging from indolent reactive lesions to malignant and aggressive diseases. Despite novel insights from high-throughput molecular studies, the pathogenesis of these disorders is not well understood, and EBV-positive T/NK LPD diagnoses remain challenging due to their rarity and considerable overlap. Indeed, this article discusses new insights into EBV-positive T/NK LPD and focuses on diagnosis challenges, describing the difficulties to clarify the borders between overlapping LPD subtypes.

Abstract

Epstein–Barr virus (EBV) is a ubiquitous virus detected in up to 95% of the general population. Most people are asymptomatic, while some may develop a wide range of EBV-associated lymphoproliferative disorders (LPD). Among them, EBV-positive T/NK LPD are uncommon diseases defined by the proliferation of T- or NK-cells infected by EBV. The 2017 World Health Organization (WHO) classification recognizes the following entities characterized by different outcomes: chronic active EBV infection of T- or NK-cell types (cutaneous and systemic forms), systemic EBV-positive T-cell lymphoma of childhood, EBV-positive aggressive NK-cell leukemia, extra nodal NK/T-cell lymphoma nasal type, and the new provisional entity known as primary EBV-positive nodal T/NK-cell lymphoma. In addition, EBV associated-hemophagocytic lymphohistiocytosis is part of EBV-positive T/NK LPD, but has not been included in the WHO classification due to its reactive nature. Despite novel insights from high-throughput molecular studies, EBV-positive NK/T-cell LPD diagnoses remain challenging, especially because of their rarity and overlap. Until now, an accurate EBV-positive NK/T LPD diagnosis has been based on its clinical presentation and course correlated with its histological features. This review aims to summarize clinical, pathological and molecular features of EBV-positive T/NK LPD subtypes and to provide an overview of new understandings regarding these rare disorders.

Oral manifestations of Hydroa vacciniforme-like lymphoproliferative disorder: a clinicopathological study of a Peruvian population

BACKGROUND

Hydroa vacciniforme-like lymphoproliferative disorder (HVLPD) is a chronic Epstein-Barr virus (EBV)-positive lymphoproliferative disease which may either present as an indolent condition or progress to a systemic T-cell lymphoma.

METHODS

All HVLPD diagnosed over a 10-year period were retrieved, and clinical data regarding sex, age, oral and systemic manifestations, and clinical follow-up were obtained. Immunohistochemistry was done in order to characterize the lymphoid cells, and in situ hybridization was used to demonstrate the presence of EBV.

RESULTS

Eleven cases were included, with a male predominance and a mean age of 25.1 years. Buccal mucosa and the lips were the most affected oral sites, appearing as painful ulcers. All patients exhibited facial oedema, usually affecting the lips, nose and periorbital region. The clinical course was gradual but progressive, with four patients having fever and 3 showing lymphadenopathies. All cases showed a moderate to severe lymphocytic infiltrate with angiotropism, angiocentricity and epidermotropism. Two cases affecting the lip skin exhibited a periappendageal lymphocytic infiltrate. Few large pleomorphic cells were found, surrounded by smaller and medium-sized lymphoid cells, as well as reactive plasma cells, macrophages, neutrophils and eosinophils. All lesions exhibited a cytotoxic T-cell (CD8+) phenotype with a variable proliferative index. All cases were associated with EBV, and all patients died due to complications of the disease.

CONCLUSIONS

HVLPD is a rare disease that may show oral involvement with a cytotoxic T-cell phenotype, and is strongly associated with EBV. As shown in this series, HVLPD may show aggressive clinical behaviour.

T Cell-Epstein-Barr Virus-Associated Hemophagocytic Lymphohistiocytosis (HLH) Occurs in Non-Asians and Is Associated with a T Cell Activation State that Is Comparable to Primary HLH

Purpose

T cell-Epstein-Barr virus–associated hemophagocytic lymphohistiocytosis (T cell-EBV-HLH) is prevalent in East Asia and has poor prognosis. Understanding of this disease is limited, and literature regarding prevalence in North America is scarce. Herein, we summarize our experience.

Methods

A retrospective analysis of T cell-EBV-HLH patients admitted to Children’s Healthcare of Atlanta (GA, USA) from 2010 to 2020 was conducted. Additional immune studies were completed in a subset of patients.

Results

We report 15 patients (10 months–19 years of age) diagnosed with T cell-EBV-HLH. Nine patients were Hispanic, and the majority did not have primary HLH (p-HLH) gene defects. Soluble interleukin-2 receptor levels in T cell-EBV-HLH were significantly higher than other forms of secondary-HLH but comparable to p-HLH, and it correlated with disease severity at presentation. Natural killer cell function was decreased in most patients despite a negative workup for p-HLH. Depending on disease severity, initial therapy included dexamethasone or dexamethasone and etoposide. Refractory patients were managed with blended regimens that included one or more of the following therapies: combination chemotherapy, alemtuzumab, emapalumab, and nivolumab. Rituximab did not appreciably decrease EBV viremia in most patients. Non-critically ill patients responded well to immunosuppressive therapy and are long-term survivors without undergoing allogeneic hematopoietic stem cell transplantation (HSCT). Alemtuzumab resulted in inflammation flare in two of the three patients. Three patients underwent allogeneic HSCT, with disease relapse noted in one. At a median follow-up of 3 years, 10 of the 15 patients are alive.

Conclusion

T cell-EBV-HLH occurs in the USA among the non-Asian populations, especially in those who are Hispanic.

Virus-Driven Carcinogenesis

Cancer arises from the accumulation of genetic and epigenetic alterations. Even in the era of precision oncology, carcinogens contributing to neoplastic process are still an important focus of research. Comprehensive genomic analyses have revealed various combinations of base substitutions, referred to as the mutational signatures, in cancer. Each mutational signature is believed to arise from specific DNA damage and repair processes, including carcinogens. However, as a type of carcinogen, tumor viruses increase the cancer risk by alternative mechanisms, including insertional mutagenesis, viral oncogenes, and immunosuppression. In this review, we summarize virus-driven carcinogenesis to provide a framework for the control of malignant cell proliferation. We first provide a brief overview of oncogenic viruses and describe their implication in virus-related tumors. Next, we describe tumor viruses (HPV, Human papilloma virus; HBV, Hepatitis B virus; HCV, Hepatitis C virus; EBV, Epstein-Barr virus; Kaposi sarcoma herpesvirus; MCV, Merkel cell polyoma virus; HTLV-1, Human T-cell lymphotropic virus, type-1) and tumor virus-related cancers. Lastly, we introduce emerging tumor virus candidates, human cytomegalovirus (CMV), human herpesvirus-6 (HHV-6) and adeno-associated virus-2 (AAV-2). We expect this review to be a hub in a complex network of data for virus-associated carcinogenesis.

Hydroa vacciniforme-like lymphoproliferative disorder: A clinicopathological, immunohistochemical, and prognostic study of 24 cases in China

Hydroa vacciniforme‐like lymphoproliferative disorder (HV‐LPD) is a rare cutaneous disease associated with Epstein–Barr virus infection. We retrospectively analyzed the clinical presentation, histopathological characteristics, and prognostic study of HV‐LPD in 24 Chinese patients. All patients presented with recurrent papulovesicular and necrotic eruptions on the face, neck, and extremities, with 11 showing systemic symptoms. Twenty patients were diagnosed with HV‐LPD in childhood (age < 18 years) and four in adulthood (age ≥ 18 years). The median age at diagnosis was 8.5 years old (range, 2–50). Histopathology revealed variably dense lymphocyte infiltration throughout the dermis. All cases were strongly positive for CD3 and Epstein–Barr encoding region based on in situ hybridization. Of 18 cases with a T‐cell phenotype, 15 harbored monoclonal rearrangements in T‐cell receptor (TCR) genes. Four cases with a natural killer cell phenotype carried polyclonal rearrangements in TCR genes. Among 24 patients, eight (33.3%) received chemotherapy, two (8.3%) allogeneic hematopoietic stem cell transplantation, and both are currently alive without disease. The median follow‐up period was 24 months (range, 7–120) and 23 patients were available: 15 (62.5%) were alive, and eight (33.3%) had died. Fourteen cases had a relapse of disease and three developed lymphoma within 24 months of diagnosis. The mean survival time of childhood‐onset patients was longer than that of adult‐onset patients (36.4 vs. 20.8 months). In summary, the wide clinical course and representative presentation of cases in our center reflect the pedigree characteristics of HV‐LPD. Allogeneic hematopoietic stem cell transplantation should be a preferred choice for relapse and refractory patients due to the poor effect of chemotherapy. Adult‐onset and high serum EBV DNA loads may indicate an increased risk of aggressive disease in patients with HV‐LPD.

Immunity to EBV as revealed by immunedeficiencies

Epstein-Barr virus infection is the most common viral latent infection in humans and represents one prototypical model to study immunity to viral infections. In that respect, inborn errors of immunity (IEIs) or primary immunodeficiencies (PIDs) predisposing to severe and chronic EBV infections provide peculiar examples to decipher-specific molecular and cellular components involved in the immune control of EBV-infected cells. Herein, we discuss the recent knowledge and concepts arising from these studies, with a particular focus on 'atypical' EBV infections when EBV enters T, NK and smooth muscle cells, instead of the common 'typical' infection of B cells.

Hydroa Vacciniforme-Like Lymphoproliferative Disorder in Korea: Prognostic Implication of Clinical Signs and Whole Blood Epstein-Barr Virus DNA

Background

Hydroa vacciniforme-like lymphoproliferative disorder (HVLPD) is rare Epstein-Barr virus (EBV)-associated disease. The classic form of HVLPD is a self-resolving disease, whereas the systemic form can progress to malignant lymphoma, resulting in fatal outcomes. However, the prognostic factors remain unclear.

Objective

This study aimed to evaluate the clinical characteristics of HVLPD and the association between whole blood EBV DNA and clinical outcomes.

Methods

We retrospectively reviewed our 25-year experience involving 11 patients with HVLPD from a single tertiary center in South Korea and evaluated the clinical characteristics of HVLPD and the correlation between whole blood EBV DNA and clinical outcomes.

Results

Of the total 11 patients, 54.5% (6/11) manifested classic HVLPD that resolved with conservative treatment, while 45.5% (5/11) patients had systemic HVLPD, four of whom died of progressive disease or hemophagocytic syndrome. Five patients with systemic HVLPD manifested severe skin lesions such as prominent facial edema, deep ulcers and necrotic skin lesions involving sun-protected areas. Median EBV DNA levels at initial diagnosis were higher in three dead patients than in those alive (2,290 vs. 186.62 copies/µl).

Conclusion

When EBV DNA levels were high, patients showed severe skin lesions and when EBV DNA levels were low, skin lesions tended to improve. Thus, patients with high EBV DNA levels showed an increased risk of severe skin lesions and disease progression.

Rapid identification and characterization of infected cells in blood during chronic active Epstein-Barr virus infection

Epstein-Barr virus (EBV) preferentially infects epithelial cells and B lymphocytes and sometimes T and NK lymphocytes. Persistence of EBV-infected cells results in severe lymphoproliferative disorders (LPDs). Diagnosis of EBV-driven T or NK cell LPD and chronic active EBV diseases (CAEBV) is difficult, often requiring biopsies. Herein, we report a flow-FISH cytometry assay that detects cells expressing EBV-encoded small RNAs (EBERs), allowing rapid identification of EBV-infected cells among PBMCs. EBV-infected B, T, and/or NK cells were detectable in various LPD conditions. Diagnosis of CAEBV in 22 patients of Caucasian and African origins was established. All exhibited circulating EBV-infected T and/or NK cells, highlighting that CAEBV is not restricted to native American and Asian populations. Proportions of EBV-infected cells correlated with blood EBV loads. We showed that EBV-infected T cells had an effector memory activated phenotype, whereas EBV-infected B cells expressed plasma cell differentiation markers. Thus, this method achieves accurate and unambiguous diagnoses of different forms of EBV-driven LPD and represents a powerful tool to study their pathophysiological mechanisms.

Hydroa Vacciniforme-like Lymphoproliferative disorder in an adult invades the liver and bone marrow with clear pathological evidence: a case report and literature review

Background

Hydroa Vacciniforme-like Lymphoproliferative Disorder (HV-LPD) is the name given to a group of Epstein-Barr virus (EBV)-associated diseases. It resembles hydroa vacciniforme (HV), the rarest form of photosensitivity, and is a T-cell disorder associated with an Epstein-Barr virus infection. The majority of diagnosed cases occur in East Asia and South America. It is rare in the United States and Europe. Multiple studies have revealed the clinical manifestation of an enlarged liver, but no gold standard such as pathology has yet supported this as a clinical sign of HV-LPD.

Case presentation

Here, we report a case of a 34-year-old Asian female with definite liver invasion. The patient had complained of a recurring facial rash for many years. The patient was admitted to the hospital because of an enlarged liver. After hospitalization, she was given an EB virus nucleic acid test. The EB virus nucleic acid test was positive, and pathological examination suggested that HV-LPD had invaded the skin, bone marrow, and liver. After being given antiviral treatment, the patient’s symptoms were mitigated.

Conclusions

Our case confirms the liver damage was caused by HV-LPD and the effectiveness of antiviral treatment.

Hydroa Vacciniforme and Hydroa Vacciniforme-Like Lymphoproliferative Disorder: A Spectrum of Disease Phenotypes Associated with Ultraviolet Irradiation and Chronic Epstein-Barr Virus Infection

Hydroa vacciniforme (HV) is a rare form of photosensitivity disorder in children and is frequently associated with Epstein–Barr virus (EBV) infection, whereas HV-like lymphoproliferative disorders (HVLPD) describe a spectrum of EBV-associated T-cell or natural killer (NK)-cell lymphoproliferations with HV-like cutaneous manifestations, including EBV-positive HV, atypical HV, and HV-like lymphoma. Classic HV occurs in childhood with papulovesicules on sun-exposed areas, which is usually induced by sunlight and ultraviolet irradiation, and mostly resolves by early adult life. Unlike classic HV, atypical or severe HV manifests itself as recurrent papulovesicular eruptions in sun-exposed and sun-protected areas associated occasionally with facial edema, fever, lymphadenopathy, oculomucosal lesions, gastrointestinal involvement, and hepatosplenomegaly. Notably, atypical or severe HV may progress to EBV-associated systemic T-cell or natural killer (NK)-cell lymphoma after a chronic course. Although rare in the United States and Europe, atypical or severe HV and HV-like lymphoma are predominantly reported in children from Asia and Latin America with high EBV DNA levels, low numbers of NK cells, and T cell clones in the blood. In comparison with the conservative treatment used for patients with classic HV, systemic therapy such as immunomodulatory agents is recommended as the first-line therapy for patients with atypical or severe HV. This review aims to provide an integrated overview of current evidence and knowledge of HV and HVLPD to elucidate the pathophysiology, practical issues, environmental factors, and the impact of EBV infection.

Hydroa vacciniforme-like lymphoproliferative disorder in Korea

Hydroa vacciniforme-like lymphoproliferative disorder (HVLPD) is a rare Epstein–Barr virus (EBV)-associated lymphoproliferative disease. The disease course of HVLPD varies from an indolent course to progression to aggressive lymphoma. We investigated the characteristics of HVLPD in Korean patients. HVLPD patients at Seoul National University Hospital between 1988 and 2019 were retrospectively analyzed. This study included 26 HVLPD patients who all presented with recurrent papulovesicular and necrotic eruption on the face, neck, and extremities. EBV was detected from the skin tissues of all patients. HVLPD was diagnosed during childhood (age < 18 years) in seven patients (26.9%) and in adulthood (age ≥ 18 years) in 19 cases (73.1%). The median age at diagnosis was 24.0 years (range 7–70 years). HVLPD has various clinical courses, from an indolent course to progression to systemic lymphoma. Fourteen patients (53.8%) developed lymphoma: systemic EBV-positive T-cell lymphoma (n = 9, 34.6%); extranodal natural killer/T-cell lymphoma, nasal type (n = 3, 11.5%); aggressive natural killer/T-cell leukemia (n = 1, 3.8%); and EBV-positive Hodgkin lymphoma (n = 1, 3.8%). Mortality due to HVLPD occurred in five patients (26.3%) in the adult group, while it was one patient (14.3%) in the child group. As lymphoma progression and mortality occur not only in childhood but also in adulthood, adult-onset cases may need more careful monitoring.

A retrospective review of phototherapy in children, at a tertiary paediatric dermatology unit

BACKGROUND/PURPOSE

To examine the efficacy, tolerability and safety of phototherapy in children, in whom there is currently a paucity of data.

MATERIALS AND METHODS

Retrospective review of children under 18 years who received narrowband UVB (NB-UVB), broadband UVB (BB-UVB) phototherapy or psoralen with UVA (PUVA) photochemotherapy between 2003 and 2017 at a tertiary Paediatric dermatology centre in Southampton, UK.

RESULTS

100 children aged 6-17 years were included. The majority of children had psoriasis (74), atopic dermatitis (10) or vitiligo (8), with others having rarer dermatoses. Grade 2 erythema or above occurred in 46% of all included children and 42% (36/86) of those receiving NB-UVB; however, grade 3 and 4 reactions were infrequent and only 3 children stopped treatment due to burning. NB-UVB was particularly effective in those with psoriasis; 55/65 (85%) significantly improved, and 72% had not relapsed after 2 years. However, its effectiveness in atopic dermatitis was less convincing; in a small group of children, 6/10 (60%) significantly improved, but 66% relapsed within 3 months.

CONCLUSIONS

Our analysis demonstrates that NB-UVB is effective in children with psoriasis and vitiligo, with potential to achieve extended periods of remission in psoriasis. Its usefulness in atopic dermatitis is less clear. The long-term safety of NB-UVB in children is still unknown, but it appears to be a well-tolerated treatment and should be considered in children for a variety of inflammatory dermatoses before progressing to immunosuppressive therapies.

Hydroa vacciniforme-like lymphoproliferative disorder: A study of clinicopathology and whole-exome sequencing in Chinese patients

BACKGROUND

Hydroa vacciniforme-like lymphoproliferative disorder (HVLPD) encompasses a rare group of Epstein-Barr virus (EBV)-associated lymphoproliferative diseases.

OBJECTIVE

To define the clinical and pathologic characteristics of HVLPD and to identify mutant genes that may be related to the development of HVLPD.

METHODS

Clinical data and archived formalin-fixed, paraffin-embedded tissue were obtained from 19 patients. Specimens were analyzed by immunohistochemistry and in situ hybridization to detect EBV-encoded RNA (EBER1/2) and for T cell receptor (TCR) gene rearrangements. Whole-exome sequencing (WES) analysis was also performed in this study.

RESULTS

Thirteen patients survived between 3-58 months (median, 21 months) during the follow-up. Six patients who were almost adults (>15 years old) and died of the disease presented with facial edema. Lactate dehydrogenase (LDH) levels were elevated, and the TCR gene rearrangement test was positive more frequently in the patients who died. Compared with Chinese patients in a similar previous report, our patients had significantly higher proliferation (in all cases, the Ki-67 index was greater than 10 %) and a more aggressive clinical course. Moreover, after WES and Sanger verification, STAT3, IKBKB, ELF3, CHD7, KMT2D, ELK1, RARB and HPGDS were screened out in our patients.

CONCLUSIONS

HVLPD refers to a heterogeneous group of cutaneous lymphoproliferative diseases with different clinical and pathological features that affect patient outcomes. Gene mutations may be correlated with the development of HVLPD, and our study may provide new therapeutic targets for HVLPD.

Epstein - Barr virus positive T and NK-cell lymphoproliferations: Morphological features and differential diagnosis

The spectrum of Epstein-Barr virus (EBV)-positive T and NK-cell lymphoproliferations is broad and ranges from reactive self-limited disorders to neoplastic processes with a fulminant clinical course. EBV plays an important role promoting lymphomagenesis, although the precise mechanisms remain elusive. EBV-positive lymphoproliferative disorders (LPD) are more common in East Asia (China, Japan, Korea and Taiwan), and Latin America suggesting a strong genetic predisposition. The revised 2016 World Health Organization (WHO) lymphoma classification recognizes the following malignant NK- and T-cell lymphomas; extranodal NK/T-cell lymphoma, nasal type (ENKTCL), aggressive NK-cell leukemia (ANKL), and the provisional entity within the group of peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) "primary EBV-positive nodal T or NK cell lymphoma". Disorders presenting mainly in children and young adults include chronic active EBV infection (CAEBV) - systemic and cutaneous forms - which are not considered malignant disorders but were included in the WHO classification for the first time because of the differential diagnosis with other T- or NK-cell lymphomas. CAEBV, cutaneous form, includes hydroa vacciniforme-like LPD (HV-LPD) and severe mosquito bite allergy (SMBA). Finally, systemic EBV-positive T-cell lymphoma of childhood was recognized as lymphoma because of its fulminant clinical course. Given the shared pathogenesis of these disorders, overlapping features are common demanding a close clinical, morphological and molecular correlation for an accurate diagnosis. This review summarizes the clinical, histopathological and molecular features of EBV-associated T and NK-cell LPD, highlighting the main features that might aid in the differential diagnosis.

Epstein-Barr virus NK and T cell lymphoproliferative disease: report of a 2018 international meeting

Epstein-Barr virus (EBV) normally infects B cells, but in some persons the virus infects T or NK cells. Infection of B cells can result in infectious mononucleosis, and the virus is associated with several B cell malignancies including Hodgkin lymphoma, Burkitt lymphoma, and diffuse large B cell lymphoma. Infection of T or NK cells with EBV is associated with extranodal NK/T cell lymphoma, aggressive NK-cell leukemia, systemic EBV-associated T-cell lymphoma, and chronic active EBV disease, which in some cases can include hydroa vacciniforme-like lymphoproliferative disease and severe mosquito bite allergy. While NK and T cell lymphoproliferative disease is more common in Asia and Latin America, increasing numbers of cases are being reported from the United States and Europe. This review focuses on classification, clinical findings, pathogenesis, and recent genetic advances in NK and T cell lymphoproliferative diseases associated with EBV.