Human herpesvirus-8-associated lymphoma of the bowel in human immunodeficiency virus-positive patients without history of primary effusion lymphoma

EBV-Driven Lymphoproliferative Disorders and Lymphomas of the Gastrointestinal Tract: A Spectrum of Entities with a Common Denominator (Part 3)

EBV is the first known oncogenic virus involved in the development of several tumors. The majority of the global population are infected with the virus early in life and the virus persists throughout life, in a latent stage, and usually within B lymphocytes. Despite the worldwide diffusion of EBV infection, EBV-associated diseases develop in only in a small subset of individuals often when conditions of immunosuppression disrupt the balance between the infection and host immune system. EBV-driven lymphoid proliferations are either of B-cell or T/NK-cell origin, and range from disorders with an indolent behavior to aggressive lymphomas. In this review, which is divided in three parts, we provide an update of EBV-associated lymphoid disorders developing in the gastrointestinal tract, often representing a challenging diagnostic and therapeutic issue. Our aim is to provide a practical diagnostic approach to clinicians and pathologists who face this complex spectrum of disorders in their daily practice. In this part of the review, the chronic active EBV infection of T-cell and NK-cell type, its systemic form; extranodal NK/T-cell lymphoma, nasal type and post-transplant lymphoproliferative disorders are discussed.

EBV-Driven Lymphoproliferative Disorders and Lymphomas of the Gastrointestinal Tract: A Spectrum of Entities with a Common Denominator (Part 2)

Epstein-Barr virus (EBV) is a common pathogen infecting people primarily early in life. The virus has the ability to persist throughout a person's life, usually in B lymphocytes. Conditions of immunodeficiency as well as the introduction of immunosuppressive therapies and the advent of transplant technologies has brought immunodeficiency-associated lymphoproliferative disorders into view, which are often driven by EBV. The group of EBV-associated lymphoproliferative disorders includes different entities, with distinct biological features, ranging from indolent disorders, which may even spontaneously regress, to aggressive lymphomas requiring prompt and adequate treatment. These disorders are often diagnostically challenging due to their overlapping morphology and immunophenotype. Both nodal and extra-nodal sites, including the gastrointestinal tract, may be involved. This review, divided in three parts, summarizes the clinical, pathological, molecular features and treatment strategies of EBV-related lymphoproliferative disorders occurring in the gastrointestinal tract and critically analyzes the major issues in the differential diagnosis. In this part of the review, we discuss plasmablastic lymphoma, extra-cavitary primary effusion lymphoma and Burkitt lymphoma.

Extracavitary primary effusion lymphoma recurring with syphilis in an HIV-infected patient

A 59-year-old Caucasian man infected with HIV, in remission from human herpes virus-8-positive extracavitary primary effusion lymphoma (EC-PEL), presented to a sexual health clinic with fever and rectal pain 10 weeks after a single episode of receptive anal sexual intercourse with another man. He was initially treated for a presumptive diagnosis of lymphogranuloma venereum proctitis, then for syphilis on positive serology. Rectosigmoidoscopy revealed a single ulcerated rectal mass; endoscopic biopsies confirmed the recurrence of EC-PEL. The patient received chemotherapy and went into remission. This is the first reported case of EC-PEL occurring synchronously with early syphilis, and specifically at the site of inoculation, which can be a major diagnostic challenge since both conditions may present with lymphadenopathy, mucosal involvement and constitutional symptoms. We reviewed the literature for similar cases and hypothesised that syphilis may have triggered the recurrence of this rare lymphoma.

KSHV-associated extracavitary primary effusion lymphoma in an HIV seronegative patient: a case report and review of the literature

Primary effusion lymphoma (PEL) is a rare type of non-Hodgkin's lymphoma presenting as a lymphomatous effusion and absence of a solid tumor mass. Extracavitary PEL (EC-PEL) is a subtype of PEL with the absence of an effusion but presence of solid tumor. PEL and EC-PEL share the same histopathologic and immunophenotypic features. Kaposi sarcoma-associated herpesvirus (KSHV) positivity is seen universally in these malignancies and is a requisite for diagnosis. Most cases are seen to occur in HIV positive individuals. We present a unique case of a 21-year-old male who presented with ongoing chest pain and right hip pain found to have an extensive lytic lesion of the right iliac bone, a paratracheal mass and a large pelvic mass. All the involved sites were FDG (F-18 fluorodeoxyglucose)-avid on PET-CT scan. The patient was seronegative for HIV with no risk factors for immunosuppression. A biopsy of the pelvic mass and bone marrow showed large atypical cells with irregular multi-lobulated nuclei, prominent nucleoli, and abundant amphophilic cytoplasm. The cells were positive for MUM1, in situ hybridization for EBV-encoded RNA (EBER), and KSHV, while negative for B-cell and T-cell markers. The patient was treated with six cycles of DA-EPOCH with a follow up PET scan showing a decrease in size of the masses and bone lesion and conversion to non-FDG-avid status. To the best of our knowledge, our case is the first in published English literature with bone involvement with EC-PEL regardless of HIV status. We review the reported cases of EC-PEL including their presentation, diagnostic features, treatment and outcomes.

HHV8/KSHV-Positive Lymphoproliferative Disorders and the Spectrum of Plasmablastic and Plasma Cell Neoplasms: 2015 SH/EAHP Workshop Report-Part 3

OBJECTIVES

The 2015 Workshop of the Society for Hematopathology/European Association for Haematopathology aimed to review immunodeficiency-related lymphoproliferative disorders with plasmablastic and plasma cell differentiation.

METHODS

The workshop panel reviewed human herpes virus 8 (HHV8)/Kaposi sarcoma herpesvirus (KSHV)-associated lesions and other lesions exhibiting plasma cell differentiation, including plasmablastic proliferations with features of myeloma/plasmacytoma, plasmablastic neoplasms presenting in extranodal sites and effusion-based lymphomas, and rendered a consensus diagnosis.

RESULTS

The spectrum of HHV8/KSHV-associated proliferations ranged from multicentric Castleman disease (MCD) to MCD with plasmablastic aggregates to HHV8+ diffuse large B-cell lymphoma and germinotrophic lymphoproliferative disorder. Comparisons across effusion-based lymphomas with and without HHV8/KSHV and plasmablastic lymphomas in immunodeficient and immunocompetent patients were discussed.

CONCLUSIONS

The presence or absence of HHV8/KSHV is a defining feature in disorders associated with Castleman disease, although their differential diagnosis and recognition of progression may be challenging. Plasmablastic proliferations overlap with myeloma/plasmacytoma as well as extranodal and effusion-based lymphomas. The involvement of Epstein-Barr virus is typically variable.

Primary effusion lymphoma involving cerebrospinal fluid, deep cervical lymph nodes and adenoids. Report of a case supporting the lymphatic connection between brain and lymph nodes

We describe an unusual presentation of primary effusion lymphoma in CSF of a 45-year-old HIV-positive man, with no evidence of involvement of pleural, peritoneal or pericardial cavities. Cytologic examination and flow cytometric analysis suggested the diagnosis, eventually made in an excised deep cervical lymph node, in which the neoplastic cells involved selectively the sinuses. This case represents the fifth reported example of CSF involvement by this type of lymphoma, and supports the alleged connection between CSF and cervical lymph nodes via lymphatic vessels. Interestingly, review of an adenoidectomy specimen obtained 9 months before presentation for nonspecific complaints showed rare clusters of neoplastic cells involving surface epithelium and chorium, a finding that might represent a homing mechanism and implies an asymptomatic, occult phase of lymphoma development.

Human Herpesvirus Type 8-associated Large B-cell Lymphoma: A Nonserous Extracavitary Variant of Primary Effusion Lymphoma in an HIV-infected Man: A Case Report and Review of the Literature

BACKGROUND

Primary effusion lymphoma (PEL) is a rare non-Hodgkin lymphoma subtype primarily seen in human immunodeficiency virus (HIV)-infected individuals with low CD4(+) cell counts and elevated HIV viral loads. It has always been associated with human herpesvirus type 8 (HHV-8) and in 80% of cases has also been associated with Epstein-Barr virus (EBV). Less commonly, PEL has presented in patients with advanced age and other conditions associated with an altered immunity, including malignancy, liver cirrhosis, and immunosuppressive medications. It is a tumor of B-cell lineage; however, it shows a "null" phenotype, rarely expressing pan-B cell surface antigens. It will usually express CD45, CD30, CD38, CD138, and MUM1 and is characterized by lymphomatous effusions in body cavities but not lymphadenopathy. It is an aggressive lymphoma, with an average median survival of < 1 year. HHV-8-associated large B-cell lymphoma (HHV-8-LBL) is a second variant of PEL that is both solid and extracavitary. It has immunoblastic and/or anaplastic morphologic features and a distinct immunohistochemical staining pattern. It could also have a different clinical presentation than that of classic PEL.

MATERIALS AND METHODS

We describe the case of a 57-year-old HIV-infected man who presented with a slow-growing and asymptomatic abdominal mass. Examination of an excisional biopsy specimen showed malignant large cells with prominent cytoplasm that were positive for pan-B cell antigen CD20, HHV-8, and EBV and negative for CD138, CD10, BCL-6, CD3, and CD30. The Ki-67 labeling index was 90%. The diagnosis was stage IIIA HHV-8-LBL, and he was treated with 6 cycles of R-EPOCH (rituximab, etoposide, vincristine, doxorubicin, cyclophosphamide, and prednisone) infusion chemotherapy. At 12 months after treatment, he was in complete remission. We also performed a Medline and Embase search to better understand the clinical findings of our patient and the unique attributes of HHV-8-LBL. Focusing our search on English language studies, we identified 83 cases of HHV-8-LBL without an effusion component. We compared these 83 cases with 118 reported cases of classic PEL.

RESULTS

The median age of the patients with HHV-8-LBL was 41 years (range, 24-77), and 96% of the cases were associated with HIV. The median age of the patients with classic PEL was 41 years (range, 26-86), and 96% of the cases were associated with HIV. Of those with HHV-8-LBL, 31 of 61 (51%) had a pre-existing diagnosis of acquired immunodeficiency syndrome (AIDS) and 47 of 63 (75%) were coinfected with EBV. In contrast, 69 of 96 patients (72%) with classic PEL had a pre-existing AIDS diagnosis and 40 of 49 (82%) were coinfected with EBV. The mean CD4(+) count of the HHV-8-LBL patients was 256 cells/μL (range, 18-1126 cells/μL) compared with 139 cells/μL (range, 2-557 cells/μL) in the classic PEL patients. The median survival time for both groups was similar at 5.5 months (range, 25 days to ≥ 25 months) for patients with HHV-8-LBL and 4 months (range, 2 days to ≥ 113 months) for those with classic PEL. More patients with HHV-8-LBL were alive at the last follow-up point (59% vs. 18%). The percentage of patients achieving complete remission was 54% (30 of 56) and 36% (32 of 89) for HHV-8-LBL and classic PEL, respectively.

CONCLUSION

Our patient's high CD4(+) cell count, the lack of a pre-existing AIDS diagnosis, and the excellent response to chemotherapy highlights that HHV-8-LBL might have distinct clinical features and possibly a better response to chemotherapy than classic PEL. HHV-8-LBL should be included in the differential diagnosis of HIV patients with solid lesions. It is essential that patients' Centers for Disease Control and Prevention HIV clinical status and HIV viral load at the diagnosis of PEL and HHV-8-LBL be reported and that the reported clinical results include longer term follow-up data. Only then will a more complete clinical picture of this little-appreciated and little-understood PEL variant be defined.

Extracavitary primary effusion lymphoma: clinical, morphological, phenotypic and cytogenetic characterization using nuclei enrichment technique

AIMS

Primary effusion lymphoma (PEL) is a rare form of aggressive B-cell lymphoma, which typically manifests as malignant effusion in the body cavities. However, extracavitary solid variants are also described. The aim of this study was to investigate copy number aberrations in two cases of solid PEL at their first occurrences and relapse by applying a newly developed methodology of tumour nuclei enrichment.

METHODS AND RESULTS

Using histological and genetic techniques, a novel protocol for tumour nuclei enrichment by flow sorting and array-comparative genomic hybridization, we characterized two cases of extracavitary PEL, one of which later relapsed as effusion. Both primary tumours were positive for HHV8 and EBV, confined to lymph nodes, and aberrantly expressed CD3, yet displaying clonal immunoglobulin gene rearrangements indicating B-cell origin. Cytogenetic characterization of primary tumours revealed modest number of aberrations, partially overlapping with previously reported affected loci. The effusional relapse in case 1 was cytogenetically related to the primary tumour but showed dramatic increase of chromosomal instability.

CONCLUSIONS

We for the first time demonstrate a cytogenetic relationship between solid and effusional presentations of PEL. Moreover, we provide an indirect evidence of multiple malignant clones, which gave rise to clonally-related, yet karyotypically different relapsing lymphoma manifestations.

Primary effusion lymphoma with aberrant T-cell phenotype in an iatrogenically immunosuppressed renal transplant male: cytologic diagnosis in peritoneal fluid

Primary effusion lymphoma (PEL) is an unusual class of non-Hodgkin's lymphoma that develops in body cavities, without associated mass lesions. It has been linked to human herpes virus 8 (HHV-8), an etiological factor of Kaposi's sarcoma. Although PEL is a B-cell lymphoma, the neoplastic cells are usually of the "null" phenotype by immunocytochemistry. The relative infrequency of this entity, the absence of wide casuistic allowing a better characterization, and its unfavorable outcome, strongly support the need of a deeper knowledge. We report the clinico-biological findings of a 49-year-old male who was iatrogenically suppressed patient for 29 years because of renal transplantation. This case was diagnosed cytologically as peritoneal PEL and confirmed histologically on peritoneal biopsies. The immune status for both HHV-8 and Epstein-Barr virus (EBV) was evaluated and showed positive immunostaining only for the former. The combination of the immunocytochemistry results with the existence of a clonal rearrangement in the immunoglobulin heavy chain gene (identified by PCR) was compatible with the diagnosis of PEL. The presence of T-cell markers was consistent with the diagnosis of PEL with an aberrant T-cell phenotype.

Extracavitary manifestation of primary effusion lymphoma as a right atrial mass

Primary effusion lymphoma (PEL) is a subset of large B cell lymphomas and has been mostly associated with human immunodeficiency virus infection. Rare cases have been reported in organ transplant recipients and chronic hepatitis C patients. It typically presents as an effusion in the pleural and pericardial spaces but rarely disseminates. However, involvement of the gastrointestinal tract, lymph nodes and bone marrow has been reported. Diagnosis is based on characteristic clinical, histopathological and immunohistochemical features. We present a case with a right atrial mass which tested positive for human herpes virus 8 (HHV-8), CD20, CD30 and lambda light chains and negative for CD138, kappa light chain, PAX5, Epstein-Barr virus, latent membrane protein 1, CD2, CD3, CD8 and CD56. Bilateral pleural effusions and pericardial effusions were noted which tested positive for HHV-8, CD30 and CD45. The patient responded well to the R-EPOCH regimen with complete resolution of the effusions and a significant decrease in the size of the right atrial mass. This case report illustrates the atypical manifestation of PEL as a right atrial mass.

Extracavitary/solid variant of primary effusion lymphoma

Primary effusion lymphoma (PEL) is a distinct clinicopathologic entity associated with human herpesvirus 8 (HHV8) infection that mostly affects patients with immunodeficiency. Primary effusion lymphoma usually presents as a malignant effusion involving the pleural, peritoneal, and/or pericardial cavities without a tumor mass. Rare cases of HHV8-positive lymphoma with features similar to PEL can present as tumor masses in the absence of cavity effusions and are considered to represent an extracavitary or solid variant of PEL. Here, we report 3 cases of extracavitary PEL arising in human immunodeficiency virus-infected men. Two patients had lymphadenopathy and underwent lymph node biopsy. One patient had a mass involving the ileum and ascending colon. In lymph nodes, the tumor was predominantly sinusoidal. The tumor involving the ileum and ascending colon presented as 2 masses, 12.5 × 10.6 × 2.6 cm in the colon and 3.6 × 2.7 × 1.9 cm in the ileum. In each case, the neoplasms were composed of large anaplastic cells, and 2 cases had "hallmark cells." Immunohistochemistry showed that all cases were positive for HHV8 and CD138. One case also expressed CD4 and CD30, and 1 case was positive for Epstein-Barr virus-encoded RNA. Evidence of B-cell differentiation was poorly developed in all tumors. These cases highlight the importance of assessing HHV8 in an anaplastic tumor that arises in a human immunodeficiency virus-positive patient and further contributes to the limited literature currently available for extracavitary PEL.

Solid variant of primary effusion lymphoma in successfully treated HIV infection: a case report

Primary effusion lymphoma (PEL) is a unique form of non-Hodgkin lymphoma, mainly met in severely immunocompromised, HIV-positive patients. PEL is aetiologically related to human herpes virus-8 (HHV-8) and it usually presents as a lymphomatous body cavity effusion in the absence of a solid tumour mass. Recently, cases of HIV-positive patients with HHV-8-positive solid tissue lymphomas, not associated with an effusion, have been reported (solid variant of PEL). The prognosis of PEL is reported to be poor. We report a case of an HIV-positive patient with a typical solid variant of PEL without effusion. Interestingly, his disease developed while being on stable antiretroviral therapy (ART) with high CD4 counts. He had a relatively long survival with chemotherapy and ART.

Kaposi sarcoma-associated herpesvirus/human herpesvirus 8 and lymphoproliferative disorders

Kaposi sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV8), is a recent addition to the list of human viruses that are directly associated with lymphoproliferative disorders. KSHV was first shown to be involved in multicentric Castleman disease and primary effusion lymphoma (PEL). Subsequently, the virus was identified in solid lymphomas, often of extranodal sites, with morphological and immunophenotypic characteristics similar to those of PEL, and in other lymphoproliferative disorders with heterogeneous clinicopathological presentations. The recent advances in our understanding of the histology, immunophenotype and pathogenesis of these KSHV-associated lymphoproliferative disorders are reviewed.

Primary effusion lymphoma

Primary effusion lymphoma (PEL) is a rare HIV-associated non-Hodgkin's lymphoma (NHL) that accounts for approximately 4% of all HIV-associated NHL. PEL has a unique clinical presentation in having a predilection for arising in body cavities such as the pleural space, pericardium, and peritoneum. PEL cells are morphologically variable with a null lymphocyte immunophenotype and evidence of human herpesvirus (HHV)-8 infection. The exact oncogenic mechanisms of HHV-8 have not been clearly defined. Treatment is usually with combination CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy and antiretroviral therapy (if HIV positive). The prognosis for PEL is poor, with a median survival time of around 6 months. As the exact molecular steps in HHV-8-driven oncogenesis are unraveled, it is hoped that more specific therapeutic targets will be revealed.

KSHV/HHV8-associated lymphomas

This review looks at the current state of knowledge on primary effusion lymphoma (PEL) and other Kaposi sarcoma herpesvirus (KSHV)/human herpesvirus 8 (HHV8)-associated lymphomas. In 1995, KSHV DNA sequences were identified within a distinct subgroup of acquired immunodeficiency syndrome-related non-Hodgkin lymphomas localized in body cavities and presenting as pleural, peritoneal and pericardial lymphomatous effusions. Subsequently, the spectrum of KSHV/HHV8-associated lymphomas has been expanded by the identification of cases of extracavitary solid lymphomas without serous effusions. Despite the diversification in the clinical presentation of KSHV/HHV8-associated lymphomas, the majority of the cases reported demonstrated similar morphology, immunophenotype and KSHV/HHV8 viral status. KSHV/HHV8 infection is also in multicentric Castleman disease-associated plasmablastic lymphoma. The exact oncogenic mechanisms of KSHV/HHV8 are not clearly defined. The prognosis for KSHV/HHV8-associated lymphomas is poor. Novel approaches for therapy, outside traditional chemotherapy with CHOP (cyclophosphamide, doxorubicin, prednisone, vincristine), have been suggested. These include the addition of antiviral therapy as well as inhibition of specific cellular targets.

Primary effusion lymphoma: a series of 4 cases and review of the literature with emphasis on cytomorphologic and immunocytochemical differential diagnosis

BACKGROUND

Primary effusion lymphoma (PEL) is a human herpes virus-8 (HHV-8)-associated and very rare type of lymphoma usually confined to the body cavities and commonly observed in human immunodeficiency virus (HIV)-infected patients. A comparison was made between the cytologic and immunocytochemical features of 4 cases of PEL encountered in the authors' department with those reported to date in the literature.

METHODS

A comprehensive comparison of the cytologic and immunocytochemical features of the 4 cases with those reported in the literature was conducted.

RESULTS

Cytologically, the most consistent features of the 4 cases and those in the literature included large cell size, moderate to abundant cytoplasm, a single nucleus in most cells with occasional bi- or multinucleated giant cells, single to multiple prominent nucleoli, and coarse chromatin. Immunocytochemically, only 2 (50%) of the current cases were of the null-phenotype compared with 93% of cases in the literature; the other 2 cases had a T-cell phenotype. Activation markers were expressed in 50% and 78% of the current cases and the literature cases, respectively. Positivity for HHV-8 was proven in the 4 cases by immunocytochemistry.

CONCLUSIONS

Cytomorphologically, PEL exhibits features bridging large cell immunoblastic and anaplastic large cell lymphoma. Although it is usually of null-phenotype, it may occasionally express B-cell or T-cell markers, rendering its distinction difficult from other lymphomatous effusions on a cytologic and immunocytochemical basis alone. Therefore, HHV-8 detection is an essential confirmatory ancillary test in suspected cases of PEL.

HHV-8-associated lymphoma: state-of-the-art review

During the first decade after the discovery of primary effusion lymphoma (PEL), sporadic and serial reports suggested that Kaposi-sarcoma-associated-herpesvirus/human-herpesvirus-8 (KSHV/HHV-8)-associated lymphomas in their liquid and solid presentation are clinically distinct, representing part of the spectrum of PEL. In HIV-seropositive patients with serous effusions, these solid lymphomas were reported before the development of an effusion lymphoma and following resolution of PEL. More recently, solid lymphomas not associated with lymphomatous effusion have been found in HIV-seropositive and HIV-seronegative patients. Despite the diversification in the clinical presentation of KSHV/HHV-8-associated lymphomas, most cases demonstrated a similar morphology, immunophenotype and KSHV/HHV-8 viral status.

KSHV/HHV-8 associated lymph node based lymphomas in HIV seronegative subjects. Report of two cases with anaplastic large cell morphology and plasmablastic immunophenotype

BACKGROUND

Kaposi sarcoma associated herpesvirus (KSHV)/human herpesvirus 8 (HHV-8) associated lymphomas, which often develop in human immunodeficiency virus (HIV) infected patients with advanced AIDS, present predominantly as primary effusion lymphoma (PEL) or, less frequently, as "solid" extracavitary based lymphomas, associated with serous effusions. These last lymphomas, also called "solid PEL", have been reported before the development of an effusion lymphoma and after resolution of PEL. Interestingly, KSHV/HHV-8 associated lymphomas that present as solid or extracavitary based lesions in HIV seropositive patients without serous effusions have been reported recently.

METHODS/RESULTS

This paper provides evidence for the existence of a previously undescribed KSHV/HHV-8 associated lymphoma in HIV seronegative patients without serous effusions. These lymphomas exhibit a predilection for the lymph nodes and display anaplastic large cell morphology. These tumours were completely devoid of common cell type specific antigens, including epithelial and melanocytic cell markers. B and T cell associated antigens and other commonly used lymphoid markers were absent or weakly demonstrable in a fraction of the tumour cells. Conversely, immunohistochemical studies showed strong immunostaining with plasma cell reactive antibodies.

CONCLUSIONS

Analysis of viral infection and immunohistological studies are of primary importance to define this lymph node based KSHV/HHV-8 associated lymphoma with anaplastic large cell morphology and plasmablastic immunophenotype occurring in HIV seronegative patients without serous effusions.

AIDS-related lymphomas: from pathogenesis to pathology

Human immunodeficiency virus (HIV)-associated lymphomas include: (1) lymphomas also occurring, although sporadically, in the absence of HIV infection. The vast majority of these lymphomas are high-grade B-cell lymphomas: Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL) with centroblastic (CB) features and DLBCL with immunoblastic (IBL) features; (2) unusual lymphomas occurring more specifically in HIV-positive patients and include two rare entities, namely 'primary effusion lymphoma' (PEL) and 'plasmablastic lymphoma' of the oral cavity. The pathological heterogeneity of acquired immunodeficiency syndrome-associated non-Hodgkin's lymphomas (AIDS-NHL) reflects the heterogeneity of their associated molecular lesions. In AIDS-BL, the molecular lesions involve activation of cMYC, inactivation of P53, and infection with Epstein-Barr virus (EBV). AIDS-IBL infected with EBV are characterised by frequent expression of latent membrane protein 1--an EBV oncoprotein. The biological heterogeneity of AIDS-NHL is highlighted by their histogenetic differences. Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV8)-associated lymphomas, which often develop in persons with advanced AIDS, present predominantly as PEL. KSHV/HHV8 has also been recently detected in solid extracavitary-based lymphomas. The KSHV/HHV8-associated solid lymphomas are (1) unusual lymphomas that occur more specifically in HIV-positive patients; (2) extracavitary and arise in nodal and/or extranodal sites; and (3) histologically, they usually display a PEL-like morphology and plasma cell-related phenotype.

Extracavitary Primary Effusion Lymphoma of the Anorectum

We report a case of an extracavitary primary effusion lymphoma occurring in the anorectum of a patient with advanced acquired immune deficiency syndrome. The morphology, null cell immunophenotype, and acquisition of plasma cell markers in this case are typical of the so-called solid variant of primary effusion lymphoma. Lymphoma cells in this case were shown to be co-infected with human herpesvirus-8 and Epstein-Barr virus. Following combination chemotherapy and highly active antiretroviral therapy, this patient has remained in clinical remission for > 3.5 years. The purpose of this report is to add another case to the emerging literature regarding the heterogeneous category of extraserous human herpesvirus-8-associated lymphomas.

Kaposi's sarcoma-associated herpesvirus: clinical, diagnostic, and epidemiological aspects

Kaposi's sarcoma-associated herpesvirus (KSHI) is one of the few viruses proven to be associated with tumorigenesis in humans. Its causal association with all clinical and epidemiological variants of Kaposi's sarcoma (KS) is well established. KSHV is also involved in the pathogenesis of primary effusion lymphoma (PEL) and a subset of multicentric Castleman's disease (MCD). Possible associations of KSHV with other clinical settings have been extensively examined. The findings from several of these studies are contradictory and are yet to be resolved. Concentrated effort over the last decade, since the initial discovery of KSHV, led to the development of several experimental systems that resulted in a better comprehension of the biological characteristics of KSHV and set the stage for the understanding of mechainisms by which diseases are induced by the virus. The development of molecular, histological, and serological tools for KSHV diagnosis allowed researchers to track the transmission and to study the epidemiology of KSHV. These assays have been applied, in particular in ambiguous cases, in order to confirm clinically and pathologically based diagnoses. Here, we review the advances in the clinical, experimental, diagnostic, and epidemiological research of KSHV.

Kaposi's sarcoma-associated herpesvirus/human herpesvirus type 8-positive solid lymphomas: a tissue-based variant of primary effusion lymphoma

Kaposi's sarcoma-associated herpesvirus (KSHV), also termed human herpesvirus type 8, is consistently identified in Kaposi's sarcoma, primary effusion lymphoma (PEL), and multicentric Castleman's disease. Here we report four cases of KSHV-bearing solid lymphomas that occurred in AIDS patients (cases 1 to 3) and in a human immunodeficiency virus (HIV)-seronegative person (case 4). The patients presented extranodal masses in the abdomen (cases 1, 3, and 4) or skin (case 2), and nodal involvement, together with Kaposi's sarcoma (case 3). The gastrointestinal tract was involved in two patients (cases 1 and 3). The patients did not develop a lymphomatous effusion. KSHV was detected in the tumor cells of all cases by immunohistochemistry and by polymerase chain reaction. Epstein-Barr virus was detected in two of the HIV-related cases. All KSHV-positive solid lymphomas exhibited PEL-like cell morphology. To investigate the relationship of these disorders to PEL and to other AIDS-associated diffuse large cell lymphomas, KSHV-positive solid lymphomas were tested for the expression of a set of genes that were previously shown by gene profiling analysis to define PEL tumor cells. The results showed that expression of this set of genes in KSHV-positive lymphomas is similar to that of PEL but distinct from KSHV-negative AIDS-associated diffuse large cell lymphomas. Because pathobiological features of KSHV-positive solid lymphomas closely mimic those of PEL, our results suggest that KSHV-positive solid lymphomas should be considered as a tissue-based variant of classical PEL, irrespective of HIV status.

High incidence of Kaposi sarcoma-associated herpesvirus infection in HIV-related solid immunoblastic/plasmablastic diffuse large B-cell lymphoma

Kaposi sarcoma-associated herpesvirus (KSHV) is known to be associated with two distinct lymphoproliferative disorders: primary effusion lymphoma (PEL) and multicentric Castleman disease (MCD)/MCD-associated plasmablastic lymphoma. We here report a high incidence of KSHV infection in solid HIV-associated immunoblastic/plasmablastic non-Hodgkin's lymphomas (NHLs), in patients lacking effusions and without evidence of (prior) MCD. Within a cohort of 99 HIV-related NHLs, 10 cases were found to be KSHV positive on the basis of immunostaining for KSHV LNA-1 as well as KSHV-specific polymerase chain reaction. All but one of the tumors coexpressed Epstein-Barr virus. Interestingly, all KSHV-positive cases belonged to a distinctive subgroup of 26 diffuse large B-cell lymphomas characterized by the expression of CD138 (syndecan-1) and plasmablastic/immunoblastic morphology. These KSHV-positive lymphomas were preceded by Kaposi sarcoma in 60% of the patients and involved the gastrointestinal tract in 80%. Our results indicate that KSHV infection is not restricted to PEL and MCD; it is also common (38%) in HIV-related solid immunoblastic/plasmablastic lymphomas.

HHV-8-Associated T-Cell Lymphoma in a Lymph Node With Concurrent Peritoneal Effusion in an HIV-Positive Man

Primary effusion lymphoma (PEL) is an uncommon large cell lymphoma, usually seen in human immunodeficiency virus (HIV)-infected patients. PEL is characterized by various clinical, histomorphologic, and immunophenotypical features, and is associated with the human herpes virus 8 (HHV-8). PEL may present as either a body cavity-based lymphomatous effusion or a solid tumor mass. Most so-called "solid PEL" usually have an extranodal location; exceptionally rarely, they occur in lymph nodes. The majority of PEL consist of malignant cells of B-cell genotype; seldom they are of T-cell origin. We report a rare case of HHV-8-associated "solid PEL" of T-cell type in a 41-year-old HIV-seropositive man with a concomitant peritoneal effusion. The T-cell lymphoma was diagnosed on the basis of morphologic, immunophenotypic, and molecular findings of a lymph node biopsy. The tumor cells strongly expressed CD45R0, CD7, CD43, MUM1/IRF4, CD30, HHV-8, and EBER, and demonstrated a clonal rearrangement of T-cell receptor-gamma chain gene. The following case provides another example of a lymph node-based "solid" PEL, demonstrating the variety within the spectrum of HHV-8-associated lymphoma.

KSHV-Positive Solid Lymphomas Represent an Extra-Cavitary Variant of Primary Effusion Lymphoma

Primary effusion lymphoma (PEL) is a unique form of non-Hodgkin lymphoma (NHL) associated with Kaposi sarcoma-associated herpesvirus (KSHV; HHV-8) that displays a distinct constellation of clinical, morphologic, immunologic, and molecular characteristics. Rare KSHV-containing immunoblastic lymphomas occurring in solid tissues have been described. Whether they represent part of the spectrum of PEL has not been determined. The morphologic, immunophenotypic, and molecular features of KSHV-positive solid lymphomas occurring in 8 HIV+/AIDS patients were systematically investigated and compared with those of 29 similarly analyzed PELs. The 8 KSHV-positive solid lymphomas were virtually indistinguishable from the 29 PELs based on morphology (immunoblastic/anaplastic), immunophenotype (CD45 positive; T cell antigen negative; CD30, EMA, CD138 positive; CD10, CD15, BCL6 negative) and genotype (100% immunoglobulin genes rearranged; no identifiable abnormalities in C-MYC, BCL6, BCL1, BCL2; and uniformly EBV positive). The only identifiable phenotypic difference was that the KSHV-positive solid lymphomas appeared to express B cell-associated antigens (25%) and immunoglobulin (25%) slightly more often than the PELs (<5% and 15%, respectively; P = 0.11 and P = 0.08, respectively). The clinical presentation and course of the patients who develop KSHV-positive solid lymphomas were also similar, except for the lack of an effusion and somewhat better survival (median 11 months vs. 3 months). However, the 3 KSHV-positive solid lymphoma patients alive without disease 11, 25, and 44 months following initial presentation were recently diagnosed patients and, unlike the other patients with KSHV-positive solid lymphomas, received anti-retroviral therapy. These findings strongly suggest that these decidedly rare KSHV-positive solid lymphomas belong to the spectrum of PEL. Therefore, we propose that the KSHV-positive solid lymphomas be designated extra-cavitary PELs.

Infection of mesothelial cells with human herpes virus 8 in human immunodeficiency virus-infected patients with Kaposi's sarcoma, Castleman's disease, and recurrent pleural effusions

Recurrent pleural effusions are common complications of hospitalized patients with human immunodeficiency virus (HIV) infection and may pose difficult diagnostic dilemmas. A common cause of recurrent pleural effusions in up to 30% of HIV-seropositive patients is pulmonary involvement by Kaposi's sarcoma, a human herpesvirus 8 (HHV 8)-related neoplasm. The pathogenesis of these effusions is unclear. These recurrent effusions, although benign, have shown significant mesothelial atypia/reactive changes of uncertain etiology. We attempted to evaluate these effusions morphologically and molecularly for the presence of HHV 8, with particular attention to mesothelial cells. All recurrent pleural effusions, as defined by any effusion tapped for cytological examination on more than two occasions, in HIV-positive patients at the National Institutes of Health were examined from 1998 to the present. Cases were stratified according to patients with and without histologically confirmed HHV 8 disease manifestations. Five patients with HHV 8 diseases (four with disseminated Kaposi's sarcoma and one with Castleman's disease) were identified. As a control group, five effusions from HIV-seropositive patients without known HHV 8-related diseases were identified. Cytological examination of effusions in patients with HHV 8-related diseases demonstrated atypical/markedly reactive mesothelial cells accompanied by a polymorphous background of lymphocytes. Molecular studies for B- and T-cell clonality in microdissected whole samples showed no definitive clones in these cases. Conversely, polymerase chain reaction (PCR) studies for the HHV 8 virus was positive in these samples. PCR studies on pure populations of microdissected mesothelial cells from the HHV 8-related effusions were positive for HHV 8 sequences, whereas those from HIV patients with non-HHV 8 related diseases were negative. Immunohistochemistry for HHV 8 (monoclonal antibody to latent nuclear antigen (LNA-1; ORF-73) on cellblock material demonstrated scattered positive mesothelial cells in three of the five cases of HHV 8-associated effusions. HHV 8 has been recently implicated in the pathogenesis of Kaposi's sarcoma and primary effusion lymphoma. Mesothelial cells in recurrent pleural effusions from patients with Kaposi's sarcoma and Castleman's disease appear to be infected with HHV 8. Additional studies need to be done to define the role of mesothelial cell infection in the pathogenesis of these HHV 8-associated effusions and define the prognostic significance.