A biophenotypic human herpesvirus 8--associated primary bowel lymphoma

Cervical radiculopathy as first presentation of CD3-positive diffuse large B-cell lymphoma of the cervico-thoracic junction

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) in rare cases can presents an unusual expression of CD3 T-cell specific antigen. We report the first case of a CD3-positive DLBCL of the cervico-thoracic junction presenting with persistent cervical radiculopathy.

CASE PRESENTATION

A 74-years-old male patient presented a severe and persistent right C8 radiculopathy associated with right-sided neck pain, progressive numbness and weakness of the right arm. The symptoms prominent during the night interfering with sleep and were resistant to anti-inflammatory drugs and cervical orthosis. Spine MRI showed a solid hypointense lesion on T2-weighted images and hyperintense on STIR sequences involving the epidural space at C7, T1 and T2. The patient underwent a C7-T1 decompressive laminectomy and left T2 hemilaminectomy with resection of the epidural tissue resulting in subtotal removal. Histology showed a DLBCL germinal center B-cell lymphoma with expression of CD3 T-cell specific antigen. Then the patient underwent adjuvant radiotherapy and chemotherapy consisting of R-CHOP protocol. At last follow-up (2 years) the patient is still in good clinical status (KPS = 80) with almost complete recovery of the cervical radiculopathy.

CONCLUSIONS

To our knowledge this is the first case of DLBLC GCB-like CD3 positive to present with radiculopathy.

A Rare Case of Extracavitary Primary Effusion Lymphoma in the Bladder and Ureter

Primary effusion lymphoma (PEL) is a rare and very aggressive large B-cell lymphoma usually presenting as serous effusions without a tumor mass. It is universally associated with human herpesvirus type-8 (HHV-8) infection. It most commonly occurs in the body cavities and rarely develops as solid tumor masses in the wall of cavity and other organs, and it has been termed as extracavitary PEL. Extracavitary PEL has been reported in the lymph nodes and extranodal sites. Here we report a rare case of extracavitary PEL occurring in the bladder and ureter of a human immunodeficiency virus (HIV)-negative 76-year-old Chinese male, presenting with right leg swelling, erythema, and pain. To the best of our knowledge, this is the first case of extracavitary PEL presenting in the bladder and ureter.

CD3-positive diffuse large B-cell lymphoma relapses as CD3-negative large B-cell lymphoma: Loss of aberrant antigen expression in B-cell lymphoma after chemotherapy

Aberrant expression of CD3 on diffuse large B-cell lymphoma (DLBCL) is rare, and its mechanism and biological significance are currently unclear. Herein we report a case of Epstein-Barr virus-negative, CD3-positive DLBCL in a 53 year-old male, who had a remote history of renal transplantation. After standard chemotherapy, the patient was in clinical remission. He relapsed three years later, but at this time with apparent loss of CD3 expression. PCR-based IGK gene rearrangement studies demonstrated clonal amplicons with an identical nucleotide size between the primary and secondary DLBCL, confirming the clonal relationship despite their phenotypic differences. To our knowledge, this is the first case of CD3-positive DLBCL that demonstrated a loss of aberrant CD3 on relapse. The chronologic change in phenotype seen in this case suggests that the source of the patient's lymphoma relapse may arise from either a quiescent subclone without CD3 expression, or from an upstream neoplastic precursor cell.

Clinical and prognostic significance of aberrant T-cell marker expression in 225 cases of de novo diffuse large B-cell lymphoma and 276 cases of other B-cell lymphomas

Expression of T-cell markers, generally investigated for immunophenotyping of T-cell lymphomas, is also observed in several types of B-cell lymphomas, including diffuse large B-cell lymphoma (DLBCL). We previously reported that CD5 expression in DLBCL is an inferior prognostic factor in the era of rituximab. However, data regarding the frequencies, histological relevance, and prognostic importance of T-cell markers other than CD5 are currently unavailable. In the present study, we comprehensively evaluated the expression of T-cell markers (CD2, CD3, CD4, CD5, CD7, and CD8) in 501 B-cell lymphomas, including 225 DLBCLs, by flow cytometry and subsequent immunohistochemistry. T-cell markers other than CD5, such as CD2, CD4, CD7, and CD8, were expressed in 27 (5%) patients, and notably, all of these cases were classified as large B-cell lymphoma subtypes: 25 DLBCLs and 2 intravascular large B-cell lymphomas. CD5 and other T-cell markers were expressed in 15% (31/225) and 10% (25/225) of DLBCL cases, respectively. Five of them co-expressed CD5 and other T-cell markers. Retrospectively analyzing the prognostic relevance of T-cell markers in 169 patients with primary DLBCL treated with rituximab-based chemotherapy, we showed that only CD5 was a strong predictor of poor survival. This study provides information about the occurrence of T-cell markers other than CD5 in B-cell lymphomas, their frequent histological subtypes, and their prognostic significance in DLBCL. CD5 was reconfirmed as a negative prognostic marker in DLBCL patients receiving rituximab-inclusive chemotherapy, whereas T-cell markers other than CD5 were found to have no impact on clinicopathological and survival analyses.

HHV8-related lymphoid proliferations: a broad spectrum of lesions from reactive lymphoid hyperplasia to overt lymphoma

Human herpesvirus 8 (HHV8)-associated lymphoid proliferations are uncommon and poorly characterized disorders mainly affecting immunosuppressed patients, especially with HIV infection. They encompass different diseases with overlapping features that complicate their classification. In addition, the role of HHV8 in reactive lymphoid hyperplasia is not well known. To analyze the clinicopathological spectrum of these lesions, we have reviewed 66 biopsies of 61 patients with HHV8 infection. All cases were also investigated for Epstein-Barr virus (EBV) and HIV infection. We identified 13 (20%) cases of HHV8-related reactive lymphoid hyperplasia, 2 (3%) HHV8 plasmablastic proliferations of the splenic red pulp, 28 (42%) multicentric Castleman disease, 6 (9%) germinotropic lymphoproliferative disorders, and 17 (26%) HHV8-related lymphomas. As expected, the pathologic subtype was predictive of overall survival (P<0.05). Forty-seven of our cases were HIV positive (77%). In addition to the classical presentation of the different entities, we identified novel and overlapping features. Reactive HHV8 proliferations were frequently associated with systemic symptoms but never progressed to overt HHV8-positive lymphoma. Two cases had a plasmablastic proliferation limited to spleen. Eight cases of multicentric Castleman disease had a previously unrecognized presentation shortly after the diagnosis of HIV infection, six cases had cavity effusions, and three showed plasmablast enriched proliferations. One germinotropic lymphoproliferative disorder was EBV negative and three occurred in HIV-positive patients, who had distinctive clinical and morphological features. Two of the HHV8-related lymphomas did not fulfill the criteria for previously recognized entities. All these findings expand the clinical and pathological spectrum of HHV8-related lymphoid proliferations, which is broader than current recognized.

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.

Epstein-Barr virus-negative diffuse large B cell lymphoma with aberrant expression of CD3 and other T cell-associated antigens: report of three cases with a review of the literature

Expression of CD3 on a mature B cell neoplasm, such as diffuse large B cell lymphoma (DLBCL), is extremely rare. When it is present, it will cause diagnostic confusion since the classification of lymphoid neoplasms is largely based on immunophenotyping to determine the cell lineage. We report three cases of DLBCL with CD3 and other T cell-associated antigens. A literature search identifies 30 additional cases of DLBCL expressing CD3, with the majority (78.6 %) displaying cytoplasmic expression, while two of our cases demonstrate membranous staining. Additionally, expression of CD3 tends to be partial and weak in both our series and the reported cases. Of the 28 cases reported in the literature that were tested for Epstein Barr Virus (EBV), 16 (57.1 %) are positive, suggesting an important role of EBV in promoting lineage ambiguity/infidelity, whereas, all three cases in our series are negative for the virus. All three cases in our series show homogeneous expression of multiple B cell specific antigens, while the reported cases show variable expression with some having B cell antigens downregulated, particularly in those cases with EBV association or anaplastic morphology. A low threshold for testing EBV status is advocated in DLBCL with phenotypic ambiguity along with panels of immunohistochemical stains and B/T cell receptor gene rearrangement analysis.

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.

The histological classification of diffuse large B-cell lymphomas

Diffuse large B-cell lymphomas (DLBCLs) are aggressive B-cell neoplasms with considerable clinical, biologic, and pathologic diversity, in part reflecting the functional diversity of the B-cell system and multiple pathways of transformation. In recent years, the advent of new high-throughput genomic technologies has provided new insights into the biology of DLBCL, leading to the identification of distinct molecular identities and novel pathogenetic pathways. This increasing complexity had led to an expanding number of entities in the World Health Organization classification. Using a multi-modality approach, the updated 2008 classification delineated some new subgroups, including DLBCLs associated with particular age groups or specific anatomic sites, as well as two borderline categories (tumors at the interface between classical Hodgkin lymphoma and DLBCL as well as between Burkitt lymphoma and DLBCL). This article reviews the histopathologic features of the various aggressive B-cell lymphoma subtypes included in the 2008 classification, with emphasis on some of the new entities as well as areas of diagnostic challenge.

The histological and biological spectrum of diffuse large B-cell lymphoma in the World Health Organization classification

Diffuse large B-cell lymphomas (DLBCLs) are aggressive B-cell lymphomas that are clinically, pathologically, and genetically diverse, in part reflecting the functional diversity of the B-cell system. The focus in recent years has been toward incorporation of clinical features, morphology, immunohistochemistry, and ever evolving genetic data into the classification scheme. The 2008 World Health Organization classification reflects this complexity with the addition of several new entities and variants. The discovery of distinct subtypes by gene expression profiling heralded a new era with a focus on pathways of transformation as well as a promise of more targeted therapies, directed at specific pathways. Some DLBCLs exhibit unique clinical characteristics with a predilection for specific anatomic sites; the anatomic site often reflects underlying biological distinctions. Recently, the spectrum of Epstein-Barr virus (EBV)-driven B-cell proliferations in patients without iatrogenic or congenital immunosuppression has been better characterized; most of these occur in patients of advanced age and include Epstein-Barr virus (EBV)-positive large B-cell lymphoma of the elderly. Human herpesvirus 8 is involved in the pathogenesis of primary effusion lymphoma, which can present as a "solid variant." Two borderline categories were created; one deals with tumors at the interface between classic Hodgkin lymphoma and DLBCL. The second confronts the interface between Burkitt lymphoma and DLBCL, so-called "B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt lymphoma" in the 2008 classification. Most cases harbor both MYC and BCL2 translocations and are highly aggressive. Another interesting entity is anaplastic lymphoma kinase-positive DLBCL, which renders itself potentially targetable by anaplastic lymphoma kinase inhibitors. Ongoing investigations at the genomic level, with both exome and whole-genome sequencing, are sure to reveal new pathways of transformation in the future.

Primary effusion lymphoma involving the cerebrospinal fluid

Primary effusion lymphoma or body cavity based lymphoma is a form of large B-cell lymphoma which usually presents as serous effusions without detectable tumor masses. It is universally associated with human herpesvirus-8 also known as Kaposi sarcoma herpesvirus. This condition, so far, has been reported in the body cavity effusions that include pleura, peritoneum, and pericardium. We report a case of primary effusion lymphoma which has involved the cerebrospinal fluid. To our knowledge, this is the first case of PEL reported in the cerebrospinal fluid.

Aggressive B-cell lymphomas: a review of new and old entities in the WHO classification

Aggressive B-cell lymphomas are clinically and pathologically diverse and reflect multiple pathways of transformation. The 2008 World Health Organization (WHO) classification reflects this complexity with the addition of several new entities and variants. Whereas MYC translocations have long been associated with Burkitt lymphoma (BL), deregulation of MYC has been shown to occur in other aggressive B-cell lymphomas, most often as a secondary event. Lymphomas with translocations of both MYC and BCL2 are highly aggressive tumors, with a high failure rate with most treatment protocols. These "double-hit" lymphomas are now separately delineated in the WHO classification as B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma (DLBCL) and BL. A MYC translocation is also found uncommonly in DLBCL, but the clinical consequences of this in the absence of a double hit are not yet fully delineated. Most recently, MYC translocations have been identified as a common secondary event in plasma cell neoplasms, seen in approximately 50% of plasmablastic lymphoma. Another area that has received recent attention is the spectrum of EBV-driven B-cell proliferations in patients without iatrogenic or congenital immunosuppression; most of these occur in patients of advanced age and include the EBV-positive large B-cell lymphomas of the elderly.

Diffuse large B-cell lymphoma associated with chronic inflammation as an incidental finding and new clinical scenarios

Diffuse large B-cell lymphoma that develops in the setting of long-standing chronic inflammation is typically associated with Epstein-Barr virus, and usually presents as tumor mass involving body cavities, as in pyothorax-associated lymphoma. It is listed as a distinct entity in the latest World Health Organization lymphoma classification. We report four cases that were incidentally discovered on histologic examination, one each in a splenic false cyst, a long-standing hydrocele, an atrial myxoma, and metallic-implant wear debris. Microscopic foci of atypical (neoplastic) large lymphoid cells were found within the contents of the cysts or curettage material, or within the stroma of the atrial myxoma. Despite the diverse clinical scenarios, all cases showed a homogeneous phenotype: positivity for B-lineage markers (CD20+, CD79a+, PAX5+), non-germinal center immunophenotype (CD10-, BCL6-/+, MUM-1+), and positivity for Epstein-Barr virus with type III latency (LMP1+, EBNA2+). The last feature supports the hypothesis that the lymphoma has arisen in a setting of 'local immunodeficiency' as a result of long-standing chronic inflammation in an enclosed space, a characteristic pathogenetic mechanism of diffuse large B-cell lymphoma associated with chronic inflammation. These cases therefore expand the spectrum of this entity to include new clinical scenarios for the development of this lymphoma type.

Primary mediastinal (thymic) large B cell lymphoma with aberrant expression of CD3: a case report with review of the literature

We report the first case of primary mediastinal large B cell lymphoma (PMBL) with aberrant expression of CD3. PMBL is a subtype of diffuse large B cell lymphoma (DLBCL) and usually presents with bulky mediastinal lesions. Lineage ambiguity/infidelity is uncommon in DLBCL but has been described in sporadic case reports/series. A literature search identifies 13 additional cases of DLBCL expressing CD3, with the majority displaying cytoplasmic expression. Of the 14 total cases, 6 are pyothorax-associated lymphoma, 4 are conventional DLBCL, 2 are plasmablastic lymphoma, one is primary effusion lymphoma and one is PMBL. Two cases show genotypic ambiguity/infidelity with dual clonal IG and TCR gene rearrangements in addition to ambiguous immunophenotypes. Of the 13 cases tested for EBV status, 11 are positive, suggesting an important role of EBV in promoting lineage ambiguity/infidelity. A low threshold for testing EBV status is advocated in DLBCL with phenotypic ambiguity along with panels of immunohistochemical and molecular studies.

Diffuse Large B-Cell Lymphoma—More Than a Diffuse Collection of Large B Cells: An Entity in Search of a Meaningful Classification

Context.—Diffuse large B-cell lymphoma is a heterogenous group of lymphomas. In this review, we present a brief description of the large number of entities recognized in the recently published (2008) World Health Organization classification of tumors of hematopoietic and lymphoid tissues.

Objective.—We highlight the unique clinicopathologic and molecular genetic features of these new and previously recognized entities, to illustrate the rational for the development of this classification. To help simplify the understanding of this now large and complex group of diseases, we have attempted to create broader subgroups of related entities. We discuss large B-cell lymphoma that are not otherwise specified, those that are based on anatomic site, those that have unique histology or phenotype or genotype, those that are associated with Epstein-Barr virus or Kaposi sarcoma–associated herpesvirus and herpesvirus 8, and those that are unclassifiable.

Data Sources.—World Health Organization classification of tumors of hematopoietic and lymphoid tissues (2008), published literature from PubMed (National Library of Medicine), and primary material from the authors' institution were reviewed.

Conclusions.—Recognition of the different subtypes of diffuse large B-cell lymphoma as described in the World Health Organization classification scheme will lead to improved understanding of the unique clinicopathologic and genetic features associated with these subtypes of lymphoma.

HIV-associated lymphomas and gamma-herpesviruses

Among the most common HIV-associated lymphomas are Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL) with immunoblastic-plasmacytoid differentiation (also involving the central nervous system). Lymphomas occurring specifically in HIV-positive patients include primary effusion lymphoma (PEL) and its solid variants, plasmablastic lymphoma of the oral cavity type and large B-cell lymphoma arising in Kaposi sarcoma herpesvirus (KSHV)-associated multicentric Castleman disease. These lymphomas together with BL and DLBCL with immunoblastic-plasmacytoid differentiation frequently carry EBV infection and display a phenotype related to plasma cells. EBV infection occurs at different rates in different lymphoma types, whereas KSHV is specifically associated with PEL, which usually occurs in the setting of profound immunosuppression. The current knowledge about HIV-associated lymphomas can be summarized in the following key points: (1) lymphomas specifically occurring in patients with HIV infection are closely linked to other viral diseases; (2) AIDS lymphomas fall in a spectrum of B-cell differentiation where those associated with EBV or KSHV commonly exhibit plasmablastic differentiation; and (3) prognosis for patients with lymphomas and concomitant HIV infection could be improved using better combined chemotherapy protocols incorporating anticancer treatments and antiretroviral drugs.

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.

Plasmablastic lymphoma presenting as a paravertebral mass in a patient with Crohn's disease after immunosuppressive therapy

The case of a 32-year-old man with a paravertebral mass and skin nodules, occurring against a background of immunosuppressive therapy for Crohn's disease, is presented. The tumours showed morphological and immunophenotypical features of plasmablastic lymphoma. To our knowledge, this is the first reported case of plasmablastic lymphoma presenting in this location, and also after immunosuppression with infliximab treatment for Crohn's disease.

A case of HHV-8-associated HIV-negative primary effusion lymphoma in Moscow

Primary effusion lymphoma is a rare tumor of B-cell derivation which is associated with human herpes virus type 8 (HHV-8) in 100% and with human immunodeficiency virus (HIV) in most of cases. The paper describes the first case in Russia of HIV(-) HHV-8(+) Epstein-Barr virus (EBV)(+) primary effusion lymphoma in a male patient aged 56 years. The tumor was located in the pleural cavity. Interestingly, the patient was HIV-negative while having a positive tumor HHV-8 test. There are only 22 similar cases described worldwide.

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.

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.

Diffuse Large B-cell Lymphomas With Plasmablastic Differentiation Represent a Heterogeneous Group of Disease Entities

Plasmablastic lymphoma was initially described as a variant of diffuse large B-cell lymphoma (DLBCL) involving the oral cavity of HIV+ patients and characterized by immunoblastic morphology and a plasma cell phenotype. However, other lymphomas may exhibit similar morphologic and immunophenotypic features. To determine the significance of plasmablastic differentiation in DLBCL and examine the heterogeneity of lymphomas with these characteristics, we examined 50 DLBCLs with low/absent CD20/CD79a and an immunophenotype indicative of terminal B-cell differentiation (MUM1/CD38/CD138/EMA-positive). We were able to define several distinct subgroups. Twenty-three tumors were classified as plasmablastic lymphoma of the oral mucosa type and showed a monomorphic population of immunoblasts with no or minimal plasmacytic differentiation. Most patients were HIV+ and EBV was positive in 74%. Eleven (48%) cases presented in the oral mucosa, but the remaining presented in other extranodal (39%) or nodal (13%) sites. Sixteen cases were classified as plasmablastic lymphoma with plasmacytic differentiation. These were composed predominantly of immunoblasts and plasmablasts, but in addition exhibited more differentiation to mature plasma cells. Only 33% were HIV+, EBV was detected in 62%, and 44% had nodal presentation. Nine cases, morphologically indistinguishable from the previous group, were secondary extramedullary plasmablastic tumors occurring in patients with prior or synchronous plasma cell neoplasms, classified as multiple myeloma in 7 of the 9. Two additional neoplasms were an HHV-8+ extracavitary variant of primary effusion lymphoma and an ALK+ DLBCL. HHV-8 was examined in 39 additional cases, and was negative in all. In conclusion, DLBCLs with plasmablastic differentiation are a heterogeneous group of neoplasms with different clinicopathological characteristics that may correspond to different entities.

Emerging pathways in the development of AIDS-related lymphomas

The clinicopathological range of AIDS-related non-Hodgkin lymphomas (NHLs) includes systemic lymphomas, primary central-nervous-system lymphomas, primary effusion lymphoma, and plasmablastic lymphoma of the oral cavity. Most AIDS-related NHLs belong to one of three categories of high-grade B-cell lymphomas: Burkitt's lymphoma, centroblastic lymphoma, and immunoblastic lymphoma. The pathological heterogeneity of AIDS-related NHL reflects the heterogeneity of their associated molecular lesions. In AIDS-related Burkitt's lymphoma, the molecular lesions involve activation of c-MYC, inactivation of p53, and infection with Epstein-Barr virus (EBV). AIDS-related immunoblastic lymphomas infected with EBV are characterised by frequent expression of latent membrane protein 1-an EBV oncoprotein. The biological heterogeneity of AIDS-related NHLs is highlighted by their histogenetic differences; AIDS-related NHLs are related to distinct B-cell subgroups (eg, germinal-centre or post-germinal-centre B cells). The phenotypic pattern of AIDS-related Burkitt's lymphomas and systemic AIDS-related centroblastic lymphomas closely reflects that of B cells in germinal centres. Conversely, the phenotype of AIDS-related immunoblastic lymphomas and AIDS-related primary effusion lymphomas reflects post-germinal-centre B cells in all cases. Despite their clinicopathological, genetic, and phenotypic heterogeneity, most lymphomas in patients with AIDS carry somatic mutations of immunoglobulin and BCL-6 genes. However, the somatic hypermutation mechanism functions aberrantly in a significant proportion of AIDS-related NHLs, causing the mutation of many genes, and possibly favouring chromosomal translocation, which may be a powerful contributor to malignant transformation. New molecular and virological evidence of such pathways and a greater knowledge of other biological features of AIDS-related NHLs may lead to new targets for pathogenetically and biologically oriented therapies.

Isolated pleural PTLD after cardiac transplantation

PREAMBLE: Epstein-Barr virus infection (EBV) and immunosuppression promote emergence of posttransplant lymphoproliferative disorders (PTLD) in patients undergoing organ transplantation.

OBJECTIVE

We report a case of PTLD confined to the pleura.

FINDINGS

The patient was a 62-year-old male who had undergone cardiac transplant in 1993 for ischemic heart disease. Seven years later, he presented with dyspnea and bilateral pleural effusions. The CT scan revealed left sided pleural base thickening. The cytology of the pleural fluid and fine needle aspirate of the pleura was both suggestive of PTLD. However, the tissue submitted for ancillary studies did not contain the diagnostic material. A clinical decision was made to withdraw immunosuppressive therapy and start rituximab. His clinical course was complicated by Pneumocystis carinii pneumonia and he died 4 months after the diagnosis of PTLD. Autopsy revealed bilateral pleural effusions with pleural nodules involving the visceral and parietal pleura of both lungs. Immunohistochemistry demonstrated B cell lineage with kappa/lambda ratio of 1. PCR studies done on the pleural nodules (postmortem specimen) revealed the presence of EBV DNA and absence of human herpes virus 8 (HHV8) DNA. In situ hybridization revealed positive staining for EBV RNA within the neoplasm.

CONCLUSION

Pleural-based PTLD is rare. Cytology in conjunction with immunophenotyping and molecular studies can be useful for a definitive diagnosis. In our case, cytology sample was suggestive of PTLD. PCR studies performed on the antemortem specimen confirmed the presence of monoclonal IgH gene rearrangement, while the postmortem specimen revealed oligoclonal IgH gene rearrangement. The change from monoclonal to oligoclonal IgH gene rearrangement suggests reversion of monoclonal to polyclonal PTLD following rituximab and CHOP therapy. We also demonstrated EBV DNA and RNA in the tumor nodules, supporting EBV-induced PTLD.

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

This report describes two cases of human herpesvirus-8 (HHV-8)-associated large cell lymphoma of the bowel in human immunodeficiency virus (HIV)-positive men. Immunohistochemistry provides evidence of HHV-8 infection of the lymphoma cells (LNA1+, vIL-6+). In both cases, lymphoma cells were coinfected by the Epstein-Barr virus. One case was of B-cell lineage, but the second one was of null phenotype with isolated expression of the CD3 molecule. However, in the latter case, assessment of B- or T-cell clonality remained elusive. The chief finding for these two cases was the lack of history of primary effusion lymphoma. There was an apparent restriction of the tumor to the large bowel in the first case. For the second case, the bowel tumor was preceded by lymph node and liver involvement. The cases suggest that the incidence of HHV-8 infection in large cell lymphoma arising in the setting of HIV infection (other than primary effusion lymphoma) may be underestimated and that the detection of the viral gene products would be appropriate for greater understanding of the pathogenesis of these tumors. HUM PATHOL 33:846-849.

Pyothorax-associated lymphoma: a peculiar clinicopathologic entity derived from B cells at late stage of differentiation and with occasional aberrant dual B- and T-cell phenotype

We report 12 European cases of pyothorax-associated lymphomas occurring 30-67 years following artificial pneumothorax for pleuropulmonar tuberculosis. Eleven patients presented with a localized pleural tumor mass, whereas one patient also had liver involvement. Histologic examination showed a diffuse proliferation of large lymphoid cells with frequent plasmacytoid differentiation (n = 8), expressing CD20 (n = 10), CD79a (n = 11), and/or CD138 (n = 5) B-cell antigens. Aberrant expression of T-cell markers (CD2, CD3, CD4) was noted in five cases. The B-cell origin of lymphoma cells was confirmed by the demonstration of immunoglobulin light chain restriction or clonal B cell population in six cases. In 11 of 12 cases in situ hybridization disclosed Epstein-Barr virus genome in most tumor cells and immunohistochemistry a type III LMP-1+/ EBNA-2+ latency profile. HHV-8/ORF73 antigen was not detected in all tested cases (n = 11). All investigated cases (10 of 10) disclosed a uniform CD10-/BCL-6-/MUM1+/CD138+/- phenotype, consistent with a derivation from late germinal center (GC)/post-GC B cells. Clinical outcome was poor with a median survival time of 5 months. Only one patient was in complete remission after 34 months. This study further confirms that pyothorax-associated lymphoma represents a distinct clinicopathologic entity among diffuse large B-cell lymphoma, which is characterized by a peculiar clinical presentation, frequent plasmacytoid features, and a strong association with EBV. Moreover, we show that this lymphoma entity likely originates from B cells at a late stage of differentiation and occasionally shares an aberrant dual B/T phenotype.