Human immunodeficiency virus (HIV)-associated polymorphic lymphoproliferative disorders

Fifth Edition of the World Health Classification of Tumors of the Hematopoietic and Lymphoid Tissues: B-cell Neoplasms

We review B-cell neoplasms in the 5th edition of the World Health Organization classification of hematolymphoid tumors (WHO-HEM5). The revised classification is based on a multidisciplinary approach including input from pathologists, clinicians, and other experts. The WHO-HEM5 follows a hierarchical structure allowing the use of family (class)-level definitions when defining diagnostic criteria are partially met or a complete investigational workup is not possible. Disease types and subtypes have expanded compared with the WHO revised 4th edition (WHO-HEM4R), mainly because of the expansion in genomic knowledge of these diseases. In this review, we focus on highlighting changes and updates in the classification of B-cell lymphomas, providing a comparison with WHO-HEM4R, and offering guidance on how the new classification can be applied to the diagnosis of B-cell lymphomas in routine practice.

Immune deficiency/dysregulation -associated lymphoproliferative disorders. Revised classification and management

Significant advances in the field of lymphoma have resulted in two recent classification proposals, the International Consensus Classification (ICC) and the 5th edition WHO. A few entities are categorized differently in the ICC compared to the WHO. Nowhere is this more apparent than the immunodeficiency lymphoproliferative disorders. The three previous versions of the WHO classification (3rd, 4th and revised 4th editions) and the ICC focused on four clinical settings in which these lesions arise for primary categorization. In contrast the 2023 WHO 5th edition includes pathologic characteristics including morphology and viral status, in addition to clinical setting, as important information for lesion classification. In addition, the 2023 WHO recognizes a broader number of clinical scenarios in which these lesions arise, including not only traditional types of immune deficiency but also immune dysregulation. With this classification it is hoped that new treatment strategies will be developed leading to better patient outcomes.

Classification of B-Cell Lymphomas and Immunodeficiency-Related Lymphoproliferations: What’s New?

New insights from genomic studies have had an impact on the definition and the diagnosis of several lymphoid tumors including follicular B-cell lymphomas, aggressive diffuse large B-cell lymphomas, and lymphoproliferations associated with acquired and posttransplant immunodeficiencies. Follicular lymphoma (FL) includes tumors whose behavior varies widely from indolent/early lesions to aggressive/transformed lymphomas. Although some large B-cell lymphomas can be subclassified as specific entities, the majority lack the characteristics necessary for subclassification and, thus, are termed diffuse large B-cell lymphoma, NOS. There have been, however, some changes in the classification of specific subtypes of large B-cell lymphoma as well as the addition of new entities, a few of which are highlighted in this article. The immunodeficiency-related lymphoproliferative disorders are currently divided into four major categories based on the clinical setting in which they arose: primary immune deficiency, post-transplant, HIV infection, and iatrogenic immunosuppression. In the two upcoming classifications systems for hematolymphoid neoplasms, International Consensus Classification (ICC) and WHO-HAEM-5, there is a divergence in the approach to categorize these lesions. Furthermore, whereas the WHO-HAEM-5 confirms the ability to classify a spectrum of EBV+ lesions as EBV+ DLBCL, NOS, the ICC has separated out lesions that are composed of a heterogenous cellular infiltrate into a new separate category, “EBV-positive polymorphic B cell lymphoproliferative disorder, NOS”. Both WHO-HAEM-5 and ICC recognize a number of KSHV/HHV8-associated lymphoid lesions and acknowledge that there is significant overlap among the different lesions. In the future, translation of these innovations in general practice requires further validation.

Impact of valganciclovir therapy on severe IRIS-Kaposi Sarcoma mortality: An open-label, parallel, randomized controlled trial

INTRODUCTION

High HHV-8 viral load (VL) in Kaposi Sarcoma (KS) has been associated with Severe Immune Reconstitution Inflammatory Syndrome (Severe-IRIS-KS), which can occur after initiating cART, and leads to high mortality, particularly in patients with pulmonary involvement. We investigate if valganciclovir (as an anti-HHV-8 agent) initiated before cART reduces the mortality associated with Severe-IRIS-KS and the incidence of Severe-IRIS-KS.

METHODS

Open-label parallel-group randomized clinical trial in AIDS cART naïve patients with disseminated KS (DKS) as defined by at least two of the following: pulmonary, lymph-node, or gastrointestinal involvement, lymphedema, or ≥30 skin lesions. In the experimental group (EG), patients received valganciclovir 900 mg BID four weeks before cART and continued until week 48; in the control group (CG), cART was initiated on week 0. Non-severe-IRIS-KS was defined as: an increase in the number of lesions plus a decrease of ≥one log10 HIV-VL, or an increase of ≥50cells/mm3 or ≥2-fold in baseline CD4+cells. Severe-IRIS-KS was defined as abrupt clinical worsening of KS lesions and/or fever after ruling out another infection following cART initiation, and at least three of the following: thrombocytopenia, anemia, hyponatremia, or hypoalbuminemia.

RESULTS

40 patients were randomized and 37 completed the study. In the ITT analysis, at 48 weeks, total mortality was the same in both groups (3/20), severe-IRIS-KS attributable mortality was 0/20 in the EG, compared with 3/20 in the CG (p = 0.09), similar to the per-protocol analysis: 0/18 in the EG, and 3/19 in the control group (p = 0.09). The crude incidence rate of severe-IRIS-KS was four patients developed a total of 12 episodes of Severe-IRIS-KS in the CG and two patients developed one episode each in the EG. Mortality in patients with pulmonary KS was nil in the EG (0/5) compared with 3/4 in the CG (P = 0.048). No difference was found between groups in the number of non-S-IRIS-KS events. Among survivors at week 48, 82% achieved >80% remission.

CONCLUSIONS

Although mortality attributable to KS was lower in the EG the difference was not statistically significant.

EBV-positive B-cell ulcerative proliferation in the oral cavity associated with EBV-negative follicular lymphoma in a patient with common variable immunodeficiency: A case report and review of the literature

Lymphoproliferative disorders (LPDs) are a group of conditions characterized by excessive production of lymphocytes manifested in various patterns including lymphadenopathy, tumor-like lesions, and lymphomas. LPD may be stimulated by Epstein-Barr virus (EBV) infection that most commonly appears in the setting of immunocompromised status such as long-term use of immunosuppressive medications and in individuals with primary immunodeficiency disorders. EBV mucocutaneous ulcer is a benign LPD reaction that mostly regresses spontaneously but sometimes requires medical or surgical intervention. This article presents a case of oral EBV mucocutaneous ulceration that affected an individual with a history of complex primary immunodeficiency disorders consisted of common variable immunodeficiency disease associated with T-cell dysfunction. This case is unique because the oral lesions led to the diagnosis of concurrent widespread EBV-negative follicular lymphomas, seemingly unrelated to her EBV-positive LPD oral disease. Yet, both occurred in the setting of severe immunosuppression from the primary immunodeficiency disorders.

From HIV to Coronavirus Disease 2019 (COVID-19): Hematologic Complications in Viral Pandemics

CONTEXT.—

From the onset of the human immunodeficiency virus (HIV) pandemic in the 1980s to the recent coronavirus disease 2019 (COVID-19) pandemic, multiple viral pandemics have occurred and all have been associated with hematologic complications of varying severity.

OBJECTIVE.—

To review the hematologic complications associated with the HIV and other viral pandemics, the current theories regarding their causation, and the incidence and clinical impact of these complications on infected patients.

DATA SOURCES.—

Peer-reviewed medical literature and the author's personal experience.

CONCLUSIONS.—

The HIV and other viral pandemics have been associated with a variety of hematologic complications that often cause significant morbidity and mortality in affected patients. HIV infection is associated with multiple hematologic disorders, many of which have a lower incidence in the era of highly active antiretroviral therapy but still represent a major clinical problem for HIV-infected patients. Our understanding of the pathogenesis of HIV-related hematologic complications, including HIV-associated lymphoproliferative disorders, has evolved in recent years. Other viral pandemics, including H1N1 influenza, severe acute respiratory syndrome (SARS) coronavirus, Middle East respiratory syndrome (MERS) coronavirus, and COVID-19, have also been associated with hematologic complications of varying severity. Our emerging understanding of the pathogenesis of the hematologic complications of HIV, COVID-19, and other viral pandemics may help in prevention, correct diagnosis, and treatment of these complications in current and future pandemics.

Immunodeficiency-Related Lymphoid Proliferations: New Insights With Relevance to Practice

PURPOSE OF REVIEW

Our understanding of risk factors and mechanisms underlying immunosuppression-related lymphoproliferative disorders continues to evolve. An increasing number of patients are living with altered immune status due to HIV, solid organ or hematopoietic stem cell transplant, treatment of autoimmune disease, or advanced age. This review covers advances in understanding, emerging trends, and revisions to diagnostic guidelines.

RECENT FINDINGS

The tumor microenvironment, including interactions between the host immune system and tumor cells, is of increasing interest in the setting of immunosuppression. While some forms of lymphoproliferative disease are associated with unique risk factors, common mechanisms are also emerging. Indolent forms, such as Epstein-Barr virus positive mucocutaneous ulcer, are important to recognize. As methods to modulate the immune system evolve, more data are needed to understand and minimize lymphoproliferative disease risk. A better understanding of individual risk factors and common mechanisms underlying immunosuppression-related lymphoproliferations will ultimately enable improved prevention and treatment of these disorders.

The Spectrum of EBV-Positive Mucocutaneous Ulcer: A Study of 9 Cases

We describe a series of 9 patients with Epstein-Barr virus (EBV)-positive mucocutaneous lymphoproliferative lesions that broadens the concept of EBV-positive mucocutaneous ulcer. We report 5 female and 4 male patients, with an average age of 74 years (range, 55 to 87 y), 2 of whom were HIV-positive. The lesions were located in the oropharynx, skin, and rectal and/or genital mucosa. Histopathologically, 6 cases showed a polymorphic pattern and 3 had a monomorphic and diffuse one, with angiotropism in 4 cases (2 each with the polymorphic and monomorphic patterns). Three of the cases expressed PDL1. In addition to its presence in the neoplastic lymphoid cells, EBV was also detected in adjacent epithelial cells in an oropharyngeal lesion. All cases responded to local therapy or adapted systemic chemotherapy in selected cases. This series extends the spectrum of this disorder to include some HIV-positive cases, patients with multiple lesions confined to a single anatomic area, lesions with an angiocentric pattern, and some cases with monomorphous large-cell cytology. We discuss the differential clinicopathologic diagnosis of this disorder and that of classic EBV large B-cell lymphoma.

Reversal of the glycolytic phenotype of primary effusion lymphoma cells by combined targeting of cellular metabolism and PI3K/Akt/ mTOR signaling

PEL is a B-cell non-Hodgkin lymphoma, occurring predominantly as a lymphomatous effusion in body cavities, characterized by aggressive clinical course, with no standard therapy. Based on previous reports that PEL cells display a Warburg phenotype, we hypothesized that the highly hypoxic environment in which they grow in vivo makes them more reliant on glycolysis, and more vulnerable to drugs targeting this pathway. We established here that indeed PEL cells in hypoxia are more sensitive to glycolysis inhibition. Furthermore, since PI3K/Akt/mTOR has been proposed as a drug target in PEL, we ascertained that pathway-specific inhibitors, namely the dual PI3K and mTOR inhibitor, PF-04691502, and the Akt inhibitor, Akti 1/2, display improved cytotoxicity to PEL cells in hypoxic conditions. Unexpectedly, we found that these drugs reduce lactate production/extracellular acidification rate, and, in combination with the glycolysis inhibitor 2-deoxyglucose (2-DG), they shift PEL cells metabolism from aerobic glycolysis towards oxidative respiration. Moreover, the associations possess strong synergistic cytotoxicity towards PEL cells, and thus may reduce adverse reaction in vivo, while displaying very low toxicity to normal lymphocytes. Finally, we showed that the association of 2-DG and PF-04691502 maintains its cytotoxic and proapoptotic effect also in PEL cells co-cultured with human primary mesothelial cells, a condition known to mimic the in vivo environment and to exert a protective and pro-survival action. All together, these results provide a compelling rationale for the clinical development of new therapies for the treatment of PEL, based on combined targeting of glycolytic metabolism and constitutively activated signaling pathways.

Pathology of lymphoma in HIV

PURPOSE OF REVIEW

HIV-infected individuals have a greatly increased risk of developing malignancies, even when HIV infection is successfully controlled with antiretrovirals. Non-Hodgkin's lymphoma is considered an AIDS-defining entity, and this disease is currently the most common type of cancer in HIV-infected individuals in the USA and Europe. Here, we describe the different types of lymphomas occurring in individuals with AIDS, and the most relevant pathologic features helpful for histologic and immunohistochemical diagnosis.

RECENT FINDINGS

The incidence of some AIDS-related lymphoma subtypes has changed since the introduction of combined antiretroviral therapy, and some of the diagnostic methodologies have evolved. New biomarkers of disease have been identified, which may be useful for diagnosis.

SUMMARY

Better pathological classification strategies and deeper molecular understanding of the different lymphoma subtypes that occur in people with AIDS will begin to allow the transition to more precise diagnosis and targeted treatments.

Lymphoid Proliferations Associated With Human Immunodeficiency Virus Infection

Context.—Individuals who are immune deficient are at an increased risk for developing lymphoproliferative lesions and lymphomas. Human immunodeficiency virus (HIV) infection is 1 of 4 clinical settings associated with immunodeficiency recognized by the World Health Organization (WHO) in which there is an increased incidence of lymphoma and other lymphoproliferative disorders.

Objectives.—To describe the major categories of benign lymphoid proliferations, including progressive HIV-related lymphadenopathy, benign lymphoepithelial cystic lesions, and multicentric Castleman disease, as well as the different types of HIV-related lymphomas as defined by the WHO. The characteristic morphologic, immunophenotypic, and genetic features of the different entities will be discussed in addition to some of the pathogenetic mechanisms.

Data Sources.—The WHO classification of tumors of hematopoietic and lymphoid tissues (2001 and 2008), published literature from PubMed (National Library of Medicine), published textbooks, and primary material from the authors' current and previous institutions.

Conclusions.—HIV infection represents one of the clinical settings recognized by the WHO in which immunodeficiency-related lymphoproliferative disorders may arise. Although most lymphomas that arise in patients with HIV infection are diffuse, aggressive B-cell lesions, other lesions, which are “benign” lymphoid proliferations, may also be associated with significant clinical consequences. These lymphoproliferations, like many other immunodeficiency-associated lymphoproliferative disorders, are often difficult to classify. Studies of HIV-associated lymphoid proliferations will continue to increase our understanding of both the immune system and lymphomagenesis.

Polymorphic lymphoid proliferations occurring in HIV-positive patients: report of a case responding to HAART

Epstein-Barr virus (EBV)-associated polymorphic lymphoid proliferations resembling polymorphic post-transplant lymphoproliferative disorders are a rare but recognised complication of the human immunodeficiency virus (HIV). These account for fewer than 5 % of HIV-associated lymphomas, and little information has been published regarding their treatment and outcome. Of the reported cases, many have presented with extranodal disease, not typical of lymphoma. We report the case of a patient presenting with lung infiltrates shown to be the result of an EBV-associated polymorphic lymphoproliferation resembling a polymorphic post-transplant lymphoproliferative disorder. The patient was simultaneously found to be HIV positive and commenced on highly active antiretroviral therapy. Without any specific anti-neoplastic treatment, the patient recovered completely and within 20 months had no symptoms or radiological evidence of a lymphoproliferative disorder. This illustrates the importance of recognising this uncommon condition in HIV-positive patients and avoiding potentially unnecessary chemotherapy.

Lymphoproliferative Lesions in the Setting of HIV Infection: A Five-Year Retrospective Case Series and Review

A wide variety of noninfectious lesions have been identified in association with HIV infection. Many hematolymphoid lesions are possible in this patient group, both reactive and neoplastic. Epidemiologic data suggests that lymphoid malignancies are among the most common neoplasms in patients with HIV. We present a selective case series assembled over a 5-year period from the relatively low HIV-prevalence Hamilton Regional Laboratory Medicine Program (HRLMP), a tertiary care referral centre in Southern Ontario. This series serves to demonstrate the wide variety of lymphoid lesions that may be encountered in patients with HIV. In addition to outlining the pathologic work-up necessary in these cases, we discuss characteristics that distinguish the HIV-associated lesions from the pathobiologically similar non-HIV-associated lymphoid lesions.

A case of HIV-associated lymphoproliferative disease that was successfully treated with highly active antiretroviral therapy

We report a case of a 41-year-old male with human immunodeficiency virus (HIV)-associated lymphoproliferative disease (LPD) who was successfully treated with highly active antiretroviral therapy (HAART). He presented with epigastralgia, and an upper endoscopic examination revealed submucosal tumors and ulcerations in his stomach. Histopathologic examination of a biopsy specimen resulted in a diagnosis of diffuse large B-cell lymphoma. He also showed systemic lymphadenopathy; whereas, a concurrent inguinal lymph node biopsy produced a diagnosis of follicular hyperplasia. He was treated with CHOP chemotherapy but the response was poor. He demonstrated several immunological abnormalities, such as eosinophilia and bone marrow insufficiency, and was suspected to be in an immunocompromised state. He was examined for HIV infection and turned out to be positive. The gastric and inguinal lymph node specimens were re-evaluated and diagnoses of HIV-LPD and HIV lymphadenitis were made, respectively. He was treated with HAART and achieved complete remission and has remained tumor-free for 20 months. To the best of our knowledge, there is no previous report in which HIV-LPD was successfully treated with antiretroviral therapy alone. It is assumed that HAART resulted in the restoration of anti-tumor immunity in this case, which led to the eradication of LPD cells.

Atypical hyperplasia of the marginal zone of B follicles in a polymorphic Epstein-Barr virus-associated lymphoproliferative disorder occurring in an adolescent with human immunodeficiency virus infection

Epstein-Barr virus (EBV)-associated lymphoid proliferations that are similar to post-transplantation lymphoproliferative disorders may occasionally occur in the setting of human immunodeficiency virus (HIV) infection. Herein, we describe such a lesion involving the adenoids in a HIV-seropositive adolescent who acquired immunity against EBV during childhood. On microscopic examination, the marginal zone of B follicles and the interfollicular area were enlarged due to the accumulation of small or intermediate-sized lymphocytes, immunoblasts, epithelioid histiocytes, and plasma cells. A few atypical immunoblasts resembling Reed-Sternberg cells were also present. Most of the cells seen in these expanded regions belonged to the B-cell lineage and displayed a phenotype consistent with that of postgerminal center B cells. No clonal rearrangement of the genes coding for the heavy chain of the immunoglobulin could be demonstrated by polymerase chain reaction analysis. In-situ hybridization studies revealed the presence of EBV early RNA in a significant number of these cells, which suggests the participation of this virus in the pathogenesis of such a B-cell proliferation. The clinical course was benign; no progression or recurrence could be seen more than 24 months after the diagnosis. This atypical lymphoproliferative disorder is probably related to polyclonal reactivation of a latent EBV infection due to a local or systemic immune imbalance induced by HIV replication. Recognition of this reactive condition is important to prevent overtreatment.

Epstein-Barr virus-associated central nervous system lymphoproliferative disease in a patient with acquired immunodeficiency syndrome responsive to highly active antiretroviral therapy

A 20-year-old man with acquired immunodeficiency syndrome (AIDS) and central nervous system (CNS) lymphoproliferative disease experienced improvement with highly active antiretroviral therapy (HAART) without radiation therapy. Our experience highlights the importance of biopsy in evaluating multifocal radiographic CNS lesions and the central role of HAART in treating AIDS-related CNS disease.

HIV infection and lymphoma

The incidence of lymphoma in patients with HIV infection greatly exceeds that of the general population. The increased risk for lymphoma appears related to multiple factors, including the transforming properties of the retrovirus itself, the immunosuppression and cytokine dysregulation that results from the disease, and, most importantly, opportunistic infections with other lymphotrophic herpes viruses such as Epstein-Barr virus and human herpesvirus 8. Histologically lymphomas fall into three groups: (1) those also occurring in immunocompetent patients; (2) those occurring more specifically in HIV-positive patients; and (3) those also occurring in patients with other forms of immunosuppression. Aggressive lymphomas account for the vast majority cases. They frequently present with advanced stage, bulky disease with high tumour burden and, typically, involve extranodal sites. Clinical outcome appears to be worse than in similar aggressive lymphomas in the general population. However, following the introduction of highly active antiretroviral therapy, the risk for developing lymphoma in the context of HIV infection has decreased and the clinical outcome has improved.

Evidence for a Multiclonal Origin of Multicentric Advanced Lesions of Kaposi Sarcoma

BACKGROUND

Kaposi sarcoma (KS) is a complex tumor of uncertain clonality. Studying the viral clonality of the human herpesvirus 8 (HHV-8) in KS to determine clonality of the tumors, a strategy that has been used previously with Epstein-Barr virus and its associated tumors, may elucidate whether multicentric (disseminated) KS lesions correspond to metastatic lesions or to expansions of independent clones.

METHODS

A series of 139 KS biopsies (from skin, lymph node, or tonsil) was obtained from 98 patients, with 59 biopsies from 18 patients with disseminated multicentric KS skin lesions. The degree of spindle cell infiltration in biopsies was established by direct observation of hematoxylin-eosin-stained sections, and HHV-8 viral load was quantified by real-time polymerase chain reaction. To determine cellular clonality, the size heterogeneity of the HHV-8-fused terminal repeat (TR) region was determined by probing of electrophoresed restricted genomic DNA from KS biopsies for the HHV-8 TR sequence.

RESULTS

HHV-8 clonality analysis was performed on the 62 samples for which sufficient DNA was obtained. Most samples corresponded to histologically nodular lesions with high spindle cell infiltration and high viral load. A clonal HHV-8 pattern was determined for 59 samples; 11 were found to be monoclonal and 48 to be oligoclonal. The informative samples that were from disseminated KS skin lesions (n = 26, from six patients) were either monoclonal or oligoclonal, and the size of HHV-8 episomes varied between these samples.

CONCLUSION

Although some tumor KS lesions were monoclonal expansions of HHV-8-infected spindle cells, most advanced lesions were oligoclonal proliferations. Furthermore, individual KS disseminated tumor skin lesions were found to represent distinct expansions of HHV-8-infected spindle cells. Thus, our results suggest that KS lesions, especially in patients with advanced skin tumors, are reactive proliferations rather than true malignancies with metastatic dissemination.

Advances in the management of HIV-related non-Hodgkin lymphoma

PURPOSE OF REVIEW

Human immunodeficiency virus infection is associated with an increased risk of non-Hodgkin lymphoma. Even with a decrease in AIDS-defining illnesses after the advent of highly active antiretroviral therapy, HIV-associated non-Hodgkin lymphoma remains an important problem.

RECENT FINDINGS

Low CD4+ T-lymphocyte count, disease stage, performance status, serum lactate dehydrogenase, and number of extranodal sites of disease are all important prognostic factors for HIV-non-Hodgkin lymphoma. Recent studies have examined the role of infusional chemotherapy, as well as immunotherapy, in the treatment of aggressive HIV-non-Hodgkin lymphoma, and autologous stem cell transplantation for relapsed or refractory HIV-non-Hodgkin lymphoma. New developments in the association of viral infection and pathogenesis of certain subtypes of HIV-non-Hodgkin lymphoma have also recently been reported.

SUMMARY

Outcomes of HIV-non-Hodgkin lymphoma are improving with the routine use of highly active antiretroviral therapy and combination chemotherapy. For aggressive HIV-non-Hodgkin lymphoma, infusional chemotherapy regimens are well tolerated and lead to complete response in about 50-75% of cases and a 2-3 years overall survival of 40-60%. The potential benefit of adding rituximab to combination chemotherapy may be offset by infectious complications in severely immunosuppressed patients. HIV-associated Burkitt lymphoma should be treated with an intensive regimen rather than standard cyclophosphamide, doxorubicin, vincristine, prednisone-like chemotherapy. Autologous stem cell transplantation should be considered for selected patients with relapsed or refractory HIV-non-Hodgkin lymphoma.

Update on extranodal lymphomas. Conclusions of the Workshop held by the EAHP and the SH in Thessaloniki, Greece

Classification and proper treatment of extranodal lymphoma is hindered by the diversity of lymphoma types and the relative rarity of many of these tumour types. In order to review controversial issues in extranodal lymphoma diagnosis, a joint Workshop of the European Haematopathology Association (EAHP) and the Society for Hematopathology (SH) was held, where 99 selected cases were reviewed and discussed. This Workshop summary is focused on the most controversial aspect of cutaneous B-cell lymphoma, other extranodal B-cell lymphomas, plasmablastic lymphoma and anaplastic large-cell lymphoma in extranodal sites, and makes practical recommendations about diagnosis and therapeutic approaches.

AIDS and associated malignancies

AIDS associated malignancies (ARL) is a major complication associated with AIDS patients upon immunosuppression. Chronically immunocompromised patients have a markedly increased risk of developing lymphoproliferative disease. In the era of potent antiretrovirals therapy (ARV), the malignant complications due to HIV-1 infection have decreased in developed nations where ARV is administered, but still poses a major problem in developing countries where HIV-1 incidence is high and ARV is still not yet widely available. Even in ARV treated individuals there is a concern that the prolonged survival of many HIV-1 carriers is likely to eventually result in an increased number of malignancies diagnosed. Malignancies that were found to have high incidence in HIV-infected individuals are Kaposi's sarcoma (KS), Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL). The incidence of NHL has increased nearly 200 fold in HIV-positive patients, and accounts for a greater percentage of AIDS defining illness in the US and Europe since the advent of HAART therapy. These AIDS related lymphomas are distinct from their counterparts seen in HIV-1 seronegative patients. For example nearly half of all cases of ARL are associated with the presence of a gamma herpesvirus, Epstein Barr virus (EBV) or human herpesvirus-8 (HHV-8)/ Kaposi's sarcoma associated herpesvirus (KSHV). The pathogenesis of ARLs is complex. B-cell proliferation driven by chronic antigenemia resulting in the induction of polyclonal and ultimately monoclonal lymphoproliferation may occur in the setting of severe immunosuppression.

AIDS-related lymphoproliferative disease

Not long after the recognition of HIV as the causative agent of AIDS, it was evident that individuals infected with HIV developed lymphoma at a greater rate than the population at large. Approximately two thirds of AIDS-related lymphoma (ARL) cases are categorized as diffuse large B-cell type, with Burkitt lymphomas comprising 25% and other histologies a much smaller proportion. Typically, these individuals have presented with advanced extranodal disease and CD4+ lymphocyte counts of less than 200/mm3. Recent clinical trials have demonstrated a better outcome with chemotherapy for ARL since the introduction of combination antiretroviral treatment, termed highly active antiretroviral therapy (HAART). For patients with relapses, solid evidence points to the safety and utility of hematopoietic-cell transplantation as a salvage modality. Coinfection with other viruses such as Epstein-Barr virus and Kaposi sarcoma-associated herpesvirus have led to the genesis of previously rare or unrecognized lymphoma subtypes such as plasmablastic and primary effusion lymphomas. The immunosuppressive impact of treatment for patients with ARL receiving chemotherapy with HAART appears transient and opportunistic infections have become less problematic than prior to HAART. Significant progress has been made in the understanding and management of ARL but outcomes still remain inferior compared to those achieved in HIV- individuals.

BIOMED-2 multiplex immunoglobulin/T-cell receptor polymerase chain reaction protocols can reliably replace Southern blot analysis in routine clonality diagnostics

To establish the most sensitive and efficient strategy of clonality diagnostics via immunoglobulin and T-cell receptor gene rearrangement studies in suspected lymphoproliferative disorders, we evaluated 300 samples (from 218 patients) submitted consecutively for routine diagnostics. All samples were studied using the BIOMED-2 multiplex polymerase chain reaction (PCR) protocol. In 176 samples, Southern blot (SB) data were also available, and the two types of molecular results were compared. Results of PCR and SB analysis of both T-cell receptor and immunoglobulin loci were concordant in 85% of samples. For discordant results, PCR results were more consistent with the final diagnosis in 73% of samples. No false-negative results were obtained by PCR analysis. In contrast, SB analysis failed to detect clonality in a relatively high number of samples, mainly in cases of low tumor burden. We conclude that the novel BIOMED-2 multiplex PCR strategy is of great value in diagnosing patients with suspected B- and T-cell proliferations. Because of its higher speed, efficiency, and sensitivity, it can reliably replace SB analysis in clonality diagnostics in a routine laboratory setting. Just as with SB results, PCR results should always be interpreted in the context of clinical, immunophenotypical, and histopathological data.

Oral malignancies in HIV disease: Changes in disease presentation, increasing understanding of molecular pathogenesis, and current management

Infection with human immunodeficiency virus (HIV) and progression to acquired immune deficiency syndrome (AIDS) are associated with a vide variety of morbidities. Local and systemic diseases can develop in association with HIV infection and may manifest themselves as malignancies of the oropharynx. Advances in HIV management, fueled by increasing understanding of molecular pathogenesis, have resulted in marked changes in the prevalence of oral malignant disease. This paper discusses recent trends in the presentation and treatment of malignancies related to HIV and AIDS with an emphasis on malignancies seen in the oral cavity.

Identification of Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA2) target proteins by proteome analysis: activation of EBNA2 in conditionally immortalized B cells reflects early events after infection of primary B cells by EBV

The Epstein-Barr virus (EBV) is a ubiquitous B-lymphotropic herpesvirus associated with several malignant tumors, e.g., Burkitt's lymphoma and Hodgkin's disease, and is able to efficiently immortalize primary B lymphocytes in vitro. The growth program of infected B cells is initiated and maintained by the viral transcription factor EBV nuclear antigen 2 (EBNA2), which regulates viral and cellular genes, including the proto-oncogene c-myc. In our study, patterns of protein expression in B cells with and without EBNA2 were analyzed by two-dimensional polyacrylamide gel electrophoresis and mass spectrometry. For this purpose, we used a conditional immortalization system for EBV, a B cell line (EREB2-5) that expresses an estrogen receptor-EBNA2 fusion protein. In order to discriminate downstream targets of c-Myc from c-Myc-independent EBNA2 targets, we used an EREB2-5-derived cell line, P493-6, in which c-Myc is expressed under the control of a tetracycline-regulated promoter. Of 20 identified EBNA2 target proteins, 11 were c-Myc dependent and therefore most probably associated with proliferation, and one of these proteins was a posttranslationally modified protein, i.e., hypusinylated eIF5a. Finally, to estimate the relevance of EBNA2 targets during early EBV infection, we analyzed the proteomes of primary B cells before and after infection with EBV. The protein expression pattern induced upon EBV infection was similar to that following EBNA2 activation. These findings underscore the value of EREB2-5 cells as an appropriate model system for the analysis of early events in the process of EBV-mediated B-cell immortalization.

Molecular markers of clonality and identity in epstein-barr virus-associated B-cell lymphoproliferative disease

Epstein-Barr virus (EBV)-associated B-cell lymphoproliferative disease may be polyclonal, oligoclonal, or monoclonal. The degree of tumor clonality reflects the disease pathogenesis and may have implications for disease diagnosis, prognosis, and treatment. In this study, specimens of EBV-associated B-cell lymphoproliferative disease obtained from immunocompromised hosts were analyzed for molecular markers of cellular and virologic clonality and virologic identity. Each tumor specimen was assessed for immunoglobulin gene JH region rearrangement, the structure of the EBV genome termini, and the EBV genotype(s) present using a new EBV genotyping assay based upon LMP-1 gene sequence variation. The results of the JH rearrangement and EBV termini assays were generally concordant in their assessment of tumor specimen clonality, and both assays contributed to establishing clonal identity between different tumor specimens. The EBV genotyping assay did not significantly contribute to the assessment of tumor clonality but did established clear virologic identity between different tumor specimens obtained from the same individual. In one individual, these three assays together characterized a multi-focal, monoclonal tumor that may have arisen through clonal selection after sequential infections with two different EBV genotypes. In summary, the JH rearrangement and EBV termini assays each provided different but complementary information on tumor clonality, while the EBV genotyping assay proved most useful for establishing virologic identity among tumors. Utilization of these three assays together may provide new insight into the pathogenesis of EBV-associated B-cell lymphoproliferative disease.

Etiology and pathogenesis of AIDS-related non-Hodgkin's lymphoma

The incidence of NHL is greatly increased in HIV-infected individuals; malignant lymphoma is the second most common neoplasm that occurs in association with AIDS. The vast majority of neoplasms are clinically aggressive, monoclonal B-cell neoplasms that exhibit Burkitt's, immunoblastic, large cell, or transitional histopathology. Approximately 80% arise systemically (nodal or extranodal) and 20% arise as primary CNS lymphomas. A small proportion of neoplasms are body cavity-based, primary effusion lymphomas that are uniquely associated with KSHV infection. Recently, HIV-associated polymorphic lymphoproliferative disorders have been described as well. AIDS-related NHLs appear to exhibit distinctive clinical characteristics according to their histopathology and anatomic site of origin. Factors that contribute to lymphoma development include HIV-induced immunosuppression, impaired immune surveillance, cytokine release and deregulation, and chronic antigenic stimulation. This environment is associated with the development of oligoclonal B-cell expansions. The appearance of NHL is characterized by the presence of a monoclonal B-cell population that displays a variety of genetic lesions, including, for example, EBV infection, MYC gene rearrangement, BCL6 gene rearrangement, P53 mutations and deletions, and RAS gene mutations. The number and type of genetic lesions vary somewhat among AIDS-related NHLs according to their histopathologic category and anatomic site of origin. These findings suggest that more than one pathogenetic mechanism is operational in the development and progression of AIDS-related NHLs. Further work is necessary to develop a complete understanding of the etiology and pathogenesis of NHL in the setting of HIV infection. AIDS-related NHL is an important biologic model for investigating the development and progression of high-grade NHLs and NHLs that develop in immunedeficient hosts.