Epstein-Barr virus-associated B-cell lymphoproliferative disorders in angloimmunoblastic T-cell lymphoma and peripheral T-cell lymphoma, unspecified

Various patterns of Epstein-Barr virus (EBV)-associated B-cell lymphoproliferation occur in patients with immunodeficiency. We studied 17 cases of T-cell lymphoma displaying extensive EBV-driven B-cell lymphoproliferation or simultaneous/subsequent EBV-associated B-cell lymphoma. In 10 cases of angioimmunoblastic T-cell lymphoma, an uncommonly prominent population of EBV+ atypical, activated, focally confluent large transformed B cells was found in the background of T-cell lymphoma. In 4 cases, an EBV-associated B-cell neoplasm (3 diffuse large B-cell lymphomas, 1 plasmacytoma) occurred in patients with T-cell lymphoma. Three cases were composite lymphomas of a peripheral T-cell lymphoma, unspecified, combined with EBV-associated diffuse large B-cell lymphoma. The transformed B-cell population displayed EBV latency types 2 and 3. Monoclonal and oligoclonal B-cell populations were detected in 5 and 6 cases, respectively. Similar to other states of immunodeficiency, disease-related and therapy-induced immunosuppression in T-cell lymphoma may lead to a prominent EBV-associated B-cell lymphoproliferation and to EBV+ B-cell neoplasms.     

Epstein–Barr virus in Reed–Sternberg G-like cells in non Hodgkin's lymphomas

In the course of our study on Hodgkin's disease (HD), ten cases of non-Hodgkin's lymphomas (NHL) containing Hodgkin and Reed-Sternberg-like (MRS) cells were encountered. Many of these cases had initially been diagnosed as HD, but on careful review of the histology, with the aid of immunophenotyping studies, they were reclassified as NHL. The presence of Epstein–Barr virus (EBV) in these HRS-like cells was investigated using a combination of EBER in situ hybridization (ISH) and immunostaining for the detection of EBV-encoded latent membrane protein (LMP). HRS-like cells in four cases (two lymphoplasmacytoid lymphomas, one Richter's transformation of lymphoplasmacytoid lymphoma, and one immunoblastic lymphoma of T-cell type) were found to be EBV-positive. In two of these cases, a second biopsy taken up to 10 years later also contained EBV in the HRS-like cells. In three of the four cases, HRS-like cells expressed the activation antigen CD30, but the expression of B- or T-cell antigens was variable. All cases of T-cell-rich B-cell lymphomas were negative for EBV. In conclusion, EBV may play a role in the development of HRS-like cells i some cases of NHL. The relationship of HRS-like cells to HRS cells of HD is discussed.     

Epstein Barr virus-associated lymphoma in HIV-infected children

The relationship between Epstein Barr Virus (EBV) and the human host is commonly benign, whereas the development of malignancy is most likely due to imbalance between the virus and host's immune system. The aim of this study was to analyze the association of EBV with pediatric lymphomas in human immunodeficiency virus (HIV) patients. Four consecutive patients with a histological and clinical diagnosis of lymphomas among 351 pediatric HIV-infected children prospectively followed up at our hospital since 1991 were studied. The cases included one diffuse fibrosis lymphocyte depletion subtype Hodgkin's lymphoma, 2 Burkitt's lymphomas, and one primary diffuse large B-cell lymphoma of the central nervous system. We assessed EBV presence by LMP-1 protein labeling by immunohistochemistry and in situ hybridization for EBERs in formalin-fixed and paraffin-embedded biopsies from all four cases. All HIV-associated lymphomas studied were found to be associated with EBV. The lymphoproliferative action of EBV may induce oncogenesis by increasing the probability of genetic alterations and/or by expanding an already malignant clone. As an oncogenic protein, LMP-1 expression by tumor cells supports the involvement of EBV in disease pathogenesis.     

High frequency of Epstein–Barr virus in Chinese peripheral T-cell lymphoma

Forty-two cases of Chinese T-cell lymphoma were studied for expression of Epstein–Barr virus (EBV) encoded RNA (EBER-1) and EBV latent membrane protein-1 (LMP-1) using in situ hybridization and immunohistochemistry, respectively. EBV was detected in tumour cells in 24/39 peripheral T-cell lymphomas (62%), comprising 18/27 pleomorphic, medium and large cell lymphomas (67%), 4/6 angioimmunoblastic lymphadenopathy-like lymphomas (67%), 2/2 Lennert's lymphomas, 0/2 anaplastic large cell lymphomas, and 0/2 T-zone lymphomas. EBV was not found in three T-lymphoblastic lymphomas. EBV was associated with 12/24 nodal (50%) compared with 12/15 extranodal (80%) peripheral T-cell lymphomas. In EBV positive nodal lymphomas, 9/12 cases (75%) contained less than 10% EBER positive tumour cells. In EBV positive extranodal lymphomas, 9/11 cases (82%) showed EBV gene expression in more than 50% of the tumour cells, and in five of these almost all tumour cells were positive. Lymphomas of the nasopharynx (mainly midline granuloma-type) showed EBER-1 expression in nearly all tumour cells. LMP-1 was detected in 19/23 EBER positive peripheral T-cell lymphomas (83%). Our results show that EBV is strongly associated with peripheral T-cell lymphomas in Chinese. An important role for the virus is suggested in lymphomas of the nasopharynx. The significance of EBV in T-cell lymphomas that contain only a minor population of virally infected tumour cells is currently unclear.     

Primary natural killer/T-cell lymphomas of the oral cavity are aggressive neoplasms

Thirty-four cases of primary non-Hodgkin’s lymphoma of the oral cavity were investigated for their clinical findings, histopathological features, immunophenotypes and association with Epstein-Barr virus (EBV). Four cases (12%) were natural killer/T-cell lymphomas, 3 (9%) were T-cell lymphomas and 27 (79%) were B-cell lymphomas. Compared with T- and B-cell lymphomas, NK/T-cell lymphomas had a male predominance (M:F 4:0), and most presented as ulceration of the palate and/or maxillary gingiva. Histologically, the lesions showed diffuse infiltration of medium-sized or large lymphoid tumour cells. Angiocentricity and/or angioinvasion were found in all 4 cases. The immunophenotypes of the NK/T-cell lymphomas were CD3+, CD43+, CD45RO+, CD56+ and TIA-1+. EBV was detected in 2 NK/T-cell lymphomas by in situ hybridization (ISH) and polymerase chain reaction (PCR) methods, and was not detected in T- and B-cell lymphomas. The survival rate of patients with NK/T-cell lymphoma was zero, but the survival rates for patients with T-cell and B-cell lymphomas were 67% and 38%, respectively. It appears that NK/T-cell lymphomas of the oral cavity have a predilection for originating in the palate and maxillary gingiva and are aggressive neoplasms. EBV positivity might be associated with more aggressive behaviour. Received: 21 January 1999 / Accepted: 14 April 1999     

Epstein–Barr virus-associated primary gastrointestinal lymphoma in non-immunocompromised patients in Korea

We examined 81 cases of primary gastrointestinal lymphomas in Korea, including 64 gastric lymphomas and 17 intestinal lymphomas, for EBV expression by EBER-1 in situ hybridization (ISH) and EBNA-1 PCR. In EBER-1 positive cases, we performed immunohistochemistry for latent membrane protein-1 (LMP-1) and EBV diffuse early antigen (EA(D)) to compare EBV latent gene expression and lytic process.   EBER-1 was detected in 15 of 81 cases of lymphomas. EBER-1 expression showed three different patterns on tumour cells; diffuse 4/81 (5%), localized 4/81 (5%), and a few scattered pattern 7/81 (9%). We regarded diffuse pattern and localized pattern as EBER-1 positive group (8/81: 10%). Diffuse pattern of EBER-1 was shown in all three T-cell lymphomas and one B-cell lymphoma. A localized pattern was seen all in B-cell lymphomas. The EBER-1 expression was 11% in the stomach (7/64) and 6% in the intestine (1/17). Five of the eight EBER-1 positive gastric lymphomas were histologically diffuse large B-cell lymphomas, and the other three were peripheral T-cell lymphoma, unspecified, one angiocentric lymphoma, and one intestinal T-cell lymphoma by REAL classification. Eight MALT type gastric B-cell lymphomas showed no EBV association. EBV nuclear antigen (EBNA-1) was detected in 15 of 45 resected cases (33%) by PCR. EBER-1 positive cases were all EBNA-1 positive. Twelve EBNA-positive/EBER-negative cases consisted of seven cases showing a few scattered EBER-1 positive lymphocytes. LMP-1 and diffuse early antigen (EA(D)) was detected in five and three cases, respectively. Although follow-up information in our series was incomplete, it seemed that there was no significant difference in their staging or prognosis between EBER-positive cases and EBER-negative group. It is concluded that EBV is associated with some lymphomas among Koreans without overt pre-existing immunodeficiency, especially in T-cell lymphomas.     

B细胞淋巴瘤与EB病毒关系的观察

为了了解我国非免疫缺陷相关B淋巴瘤是否与EBV有关，我们采用EBVencodedsmallRNA（EBER－1）原位杂交对127例非免疫缺陷相关B淋巴瘤进行了研究。结果显示，其中8例瘤细胞核内有EBER－1的表达（中心母细胞型4例；淋巴浆细胞样型、浆细胞型、免疫母细胞型和不能分型的高度恶性B细胞淋巴瘤各1例），检出率为6．3％。这一结果与欧美的情况一致（5％左右）．但明显低于我国何杰金病（82％）及T淋巴细胞（62％）的检出率，因此提示EBV在非免疫缺陷B淋巴瘤发病中的作用是有限的，主要致病因素还有待进一步研究。     

Nodal T/NK-cell lymphoma of nasal type: a clinicopathological study of six cases

Aims:  To investigate the clinicopathological features of six unusual cases of nodal CD56+ and Epstein–Barr virus (EBV)+ T/natural killer (NK)-cell lymphoma, a putative nodal counterpart of nasal NK/T-cell lymphoma (nodal T/NK-cell lymphoma of nasal type) in comparison with nasal NK/T-cell lymphoma with secondary lymph node involvement ( n  = 24) and peripheral T-cell lymphoma (PTCL) of cytotoxic molecule (CTM)+ and EBV+ type ( n  = 21).
Methods and results:  All cases of nodal T/NK-cell lymphoma of nasal type exhibited diffuse infiltration of pleomorphic medium-sized to large tumour cells, reminiscent of those in CTM+ EBV+ PTCL. The tumour cells had a typical phenotype of nasal NK/T-cell lymphoma: CD2+, CD3ε+, CD4−, CD5−, CD56+, T-cell intracellular antigen-1+, granzyme B+, perforin+ and EBV+. However, four of six cases demonstrated clonal T-cell receptor γ-gene rearrangement on polymerase chain reaction analysis, unlike nasal NK/T-cell lymphoma. Comparison of clinical parameters and overall survival among the three groups demonstrated only minor differences.
Conclusions:  Nodal T/NK-cell lymphoma may occupy the grey zone between extranodal nasal-type NK/T-cell lymphoma and nodal CTM+ PTCL in a spectrum of NK to T-cell lymphomas that are EBV+. The close relationship between NK/T-cell lymphomas and cytotoxic T-cell lymphomas was also substantiated.     

Increased number of Epstein-Barr virus latently infected B-cells in T-cell non-Hodgkin's lymphoma tissues

Summary Epstein-Barr virus (EBV) is a causative agent of malignant lymphomas occurring in immunocompromised hosts. Similar lymphoid tumors can be induced in mice with severe combined immunodeficiency (SCID mice) by transplanting human B-cells with latently infected EBV. We have previously observed that when apparently EBV-negative lymphomas were engrafted into SCID mice, 11 of 18 T-cell non-Hodgkin's lymphomas (NHLs) produced EBV associated lymphomas, but only 2 of 30 engrafted with B-NHLs. Previous studies suggested that EBV-infected cell inducing lymphomas in SCID mice may preferentially exist in T-cell NHL tissues. To prove this assumption, in situ hybridization (ISH) using oligonucleotide probes for EBV-encoded small RNAs 1 (EBER1) was used in this study to demonstrate EBV-bearing lymphocytes in NHL tissues. It was found that EBV-bearing cells existe in 9 of the 10 T-cell NHL surgical specimens. By contrast, in B cell NHLs, only 2 of 10 carried EBV-bearing cells. Further semi-quantitative analysis demonstrated that apparently significantly more EBV-bearing cells were present in T-cell NHL tissues than in B-cell NHLs. Moreover, these EBV-bearing cells in lymphoma tissues were shown to be of B-cell lineage, by the combinated analysis of immunostaining with CD20 and ISH with EBER1. These results indicated the increase of EBV-bearing B-cells in T-cell NHL tissues, suggesting the activation of B-cells with latently infected EBV by neoplastic T-cells.     

T细胞淋巴瘤中爱泼斯坦-巴尔病毒感染情况的研究

目的　通过检测不同类型T细胞淋巴瘤中爱泼斯坦 巴尔病毒 (EBV)基因编码产物EBERs的表达 ,探讨EBV与T细胞淋巴瘤的关系。方法　应用原位杂交的方法 ,对 6 0例经组织学和免疫组织化学确定的T细胞淋巴瘤中EBV编码的小RNAEBERs进行检测 ,并采用 1994年淋巴瘤REAL分类方案对 6 0例T细胞淋巴瘤进行分类 ,以进一步分析与EBV相关的T细胞淋巴瘤的临床病理特征。结果　发现 6 0例T细胞淋巴瘤中EBERs的检出率为 6 1.7% ,外周T细胞淋巴瘤的检出率为6 9 8%。结外淋巴瘤的检出率高于结内淋巴瘤 (P <0 .0 1)。EBERs在T细胞淋巴瘤中的血管中心性T细胞淋巴瘤、血管免疫母T细胞淋巴瘤、间变性大细胞淋巴瘤中的检出率分别为 17 18,2 2和 4 6 ,与外周T细胞淋巴瘤非特异型 (5 1.9% ,14 2 7)相比 ,差异有非常显著意义 (P <0 .0 1)。EBERs与T细胞淋巴瘤患者的性别、年龄和临床分期无关 (P <0 .0 5 )。结论　外周T细胞淋巴瘤与EBV感染有关 ,尤其是外周T细胞淋巴瘤中的血管中心性T细胞淋巴瘤、血管免疫母T细胞淋巴瘤和间变性大细胞淋巴瘤。     

Malignant lymphoma of the thyroid. A 30-year clinicopathologic experience and an evaluation of the presence of Epstein-Barr virus.

Lymphoma of thyroid is uncommon, and Epstein-Barr virus (EBV) is found in many lymphomas. We studied the clinicopathologic characteristics in Hong Kong Chinese and analyzed the presence of EBV in thyroid lymphomas by reviewing data collected during 3 decades. We studied EBV gene expression by in situ hybridization and immunohistochemistry. Primary thyroid lymphomas were found in 23 patients (diffuse large B-cell lymphoma, 18; marginal zone B-cell lymphoma, 4; plasmacytoma, 1), and secondary lymphomas were found in 9 patients (diffuse large B-cell lymphoma, 3; Burkitt lymphomas, 2; Burkitt-like lymphoma, 1; hairy cell leukemia, 1; nasal T-cell and natural killer cell lymphoma, 1; and intestinal T-cell lymphoma, 1). Primary thyroid lymphomas were large (mean, 7 cm), found commonly in older women, and often misdiagnosed as undifferentiated carcinomas. Fine-needle aspiration was not helpful for diagnosis. Fifteen patients had Hashimoto thyroiditis. A history of thyrotoxicosis was found in 3 patients, and coexistence of 3 diseases (papillary microcarcinomas, primary thyroid lymphoma, and Hashimoto thyroiditis) was found 4 patients. The 5-year survival rate for primary thyroid lymphoma was 53%. Combined surgery and radiotherapy seemed to be the best treatment. Secondary thyroid lymphomas often were asymptomatic. EBV messenger RNAs were detected in 1 primary and 1 secondary thyroid lymphoma. The EBV gene expression in primary thyroid lymphoma showed a type II latency pattern. Thyroid lymphomas in Chinese had important clinicopathologic features. EBV may have a role in a subset of cases.     

胃T细胞淋巴瘤临床病理观察

目的 探讨胃T细胞淋巴瘤的临床病理学特点.方法 收集7例胃T细胞淋巴瘤病例标本,对其进行了临床病理分析、免疫组织化学检测、EBER原位杂交检测及T细胞受体(TCR)基因重排检测.结果 7例病例中6例为男性,1例为女性,平均发病年龄为45岁.6例可获得资料的病例中,1例有长期腹泻史,5例有低蛋白血症.组织学上,7例标本中,有5例表现为肿瘤细胞体积较大而不一致,2例表现为大小一致的中等细胞.1例病例可见肿瘤细胞浸润腺上皮.所有病例的肿瘤组织均不表达CD20及CD79a.7例病例中,各有6例表达CD3及T细胞胞质内抗原,各有4例表达CD5、βF-1及CD30,有3例表达CDM,各有1例病例表达CD8、CD56、问变性淋巴瘤激酶及粒酶B.7例病例肿瘤细胞EBER原位杂交检测均为阴性且都存在TCR基因克隆性重排.结论 胃T细胞淋巴瘤是一种少见的恶性淋巴瘤,具有独特的临床病理特点.     

Detection of Epstein–Barr virus small RNAs in routine paraffin sections using non-isotopic RNA/RNA in situ hybridization

The Epstein–Barr virus (EBV) is associated with an increasing range of reactive and neoplastic lesions. There is a need for a sensitive and specific method for detecting latent EBV in routine histological sections. We report the use of a highly sensitive paraffin section RNA/RNA in situ hybridization (ISH) technique using digoxigenin-labelled antisense riboprobes for demonstrating EBV encoded-small RNAs (EBERs), EBV gene products that are transcribed in abundance during latent EBV infection. We applied EBER-ISH to 846 paraffin embedded specimens, including cases of reactive lymphoid hyperplasia ( n = 28), infectious mononucleosis (16), Burkitt's lymphoma (44), immunodeficiency-associated lymphomas in transplant recipients (9) and AIDS patients (128), Hodgkin's disease (130), CD30 antigen positive lymphomas (106), peripheral T-cell lymphomas (104), sporadic B-cell non-Hodgkin's lymphomas (162), undifferentiated nasopharyngeal carcinoma (86), salivary gland lymphoepithelioma (11), and oral hairy leukoplakia (5). Strong, reproducible EBER staining was seen in EBV latently infected cells in archival surgical biopsy and autopsy specimens. EBER-ISH is specific, has a sensitivity comparable to that of the polymerase chain reaction, and is now the method of choice for the in situ detection of latent EBV infection.     

Primary non-Hodgkin's lymphoma of the intestine: a morphological, immunohistochemical and clinical study of 31 Chinese cases

Thirty-one cases of primary non-Hodgkin's lymphoma of the intestine were investigated. Twenty-one were of B-cell and 10 of T-cell origin. The B-cell lymphomas comprised two cases of low-grade B-cell lymphoma of mucosaassociated lymphoid tissue (MALT), one of centroblastic/centrocytic type, three of high-grade B-cell lymphoma coexisting with a low-grade B-cell lymphoma of MALT, nine of centroblastic, three of immunoblastic and three of Burkitt type. Of the T-cell lymphomas, eight were of pleomorphic medium-to large-sized cell type and two of large cell anaplastic type. All the B-cell lymphomas expressed CD20 (L26) and/or Ki-B5; in six there was monotypic immunoglobulin light chain restriction. Membrane positivity for CD45RO (UCHL1) was observed in the 10 cases of T-cell lymphoma, but the tumour cells did not express monocyte-macrophage markers. Clinically, the patients with T-cell lymphomas were usually young males with constitutional symptoms and their prognosis was significantly worse than those of patients with intestinal B-cell lymphoma.     

Frequent detection of Epstein–Barr virus-infected B cells in peripheral T-cell lymphomas

Although Epstein–Barr virus (EBV) positivity has been described in peripheral T-cell lymphomas (PTCLs) in Chinese patients, the cellular lineage of EBV-harbouring cells is unknown. Forty-four cases of PTCL were therefore studied by in situhybridization (ISH) for EBV-encoded small non-polyadenylated RNA 1 and 2 (EBER), and the lineage of the EBER+ cells was determined by double labelling. The findings were further correlated with the clonality of EBV and the genotype of these EBER+ tumours. The results for the detection of EBV by ISH show that 23 of the 44 cases were EBER+. In 5/23 of the EBER+ cases, EBER was found in around 50 per cent of atypical cells and in 18/23 cases, EBER was found in a subpopulation of atypical cells. Amongst the EBER+ cases, all 15 tested showed clonal T-cell receptor gene rearrangement by Southern blot hybridization. Double labelling was successfully done in 11 EBER+ cases, and by comparison, EBER+/CD20+ B cells outnumbered the EBER+/CD3+ T cells in all these cases. EBV clonality analysis revealed that EBV was monoclonal in six EBER+ cases and biclonal in three cases. With the predominance of EBV+ B cells over EBV+ neoplastic T cells being observed in most of these cases, it is possible that the EBV-infected clonal population may be of B-cell lineage. This was supported in some cases where a faint clonal band was seen over a background smear in the gene rearrangement study of immunoglobulin heavy chain gene by polymerase chain reaction (PCR), indicating a minor B-cell clone. It is concluded that in EBV+ PTCL, EBV is preferentially localized in B cells rather than neoplastic T cells. The neoplastic T cells may support the clonal proliferation of a subpopulation of EBV+ B cells in PTCLs. © 1998 John Wiley & Sons, Ltd.     

Human immunodeficiency virus (HIV) and Epstein-Barr virus (EBV) related lymphomas,pathology view point

The contribution of Epstein Barr virus (EBV) and Kaposi sarcoma herpes virus (KSHV) to the development of specific types of malignant lymphomas occurring in the human immunodeficiency virus (HIV) setting has been extensively studied since the beginning of the HIV epidemic 35 years ago. The introduction of highly active antiretroviral therapies (HAART) in 1996 has changed dramatically the incidence of HIV-related malignancies. Nevertheless, malignant lymphomas continue to be the major group of malignances observed in HIV infected individuals, and the most common cause of cancer related-deaths. Common features of the predominant B-cell lymphomas in the HIV⁺ setting are the frequent plasmacytoid morphology of the neoplastic cells, advanced stage, aggressive disease and frequent extranodal involvement. In this article, we review the evolving concepts and definitions of the various EBV-associated lymphomas in HIV⁺ patients, including diffuse large B-cell lymphoma, Burkitt lymphoma, classical Hodgkin lymphoma, plasmablastic lymphoma and primary effusion lymphoma. The current knowledge regarding the pathogenesis of these malignancies, the interplay between HIV and EBV co-infection in the development of certain HIV related lymphomas, and the emerging paradigm that suggests that HIV may play a direct role in lymphomagenesis are explored as well.     

Malignant lymphoma in patients with systemic rheumatic disease (rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, and dermatomyositis): a clinicopathologic study of 24 Japanese cases

We conducted clinicopathologic and immunohistochemical analyses of the prevalence of Epstein-Barr virus (EBV) among 24 patients with malignant lymphoma complicating systemic rheumatic diseases. (SRD) These 24 patients included 17 with rheumatoid arthritis (RA), 3 with systemic lupus erythematosus (SLE), 2 with systemic sclerosis (SS), and 2 with dermatomyositis (DM). There were 2 men and 22 women ranging in age from 30 to 86 years (mean: 64 years). The interval between the onset of rheumatic disease and that of malignant lymphomas ranged from 3 months to 35 years (mean: 142 months). The use of immunosuppressive drugs before the onset of malignant lymphoma was recorded in 15 patients. Among them, 5 patients received methotrexate (MTX) therapy. Malignant lymphomas were found at extranodal sites in 9 patients, and the disease was in the advanced stage in 17 patients. Histologic and immunohistochemical studies demonstrated that 18 cases (75%) were B-cell lymphoma (RA=12, SLE=2, SS=2, DM=2), 3 (12.5%) were peripheral T-cell lymphoma (RA=3), and 3 (12.5%) were classical Hodgkin lymphoma (RA=2, SLE=1). As in previous reports, there was an increased frequency of diffuse large B-cell lymphoma (50%) in the present series. Moreover, a majority of the diffuse large B-cell lymphomas exhibited activated B-cell phenotype. EBV-encoded small RNAs (Epstein-Barr early region [EBER]-) and/or LMP-1+tumor cells were identified in only 3 cases of classical Hodgkin lymphomas. Our findings suggested EBV-associated lymphoma comprised only a small fraction of all non-Hodgkin's lymphomas in the general SRD patient population.     

A survey of Epstein-Barr virus gene expression in sporadic non-Hodgkin''s lymphomas. Detection of Epstein-Barr virus in a subset of peripheral T-cell lymphomas.

This study analyzes the association of Epstein-Barr virus (EBV) with non-Hodgkin's lymphoma (NHL) arising in patients without pre-existing overt immunodeficiency. The authors examined 201 lymphomas (105 high-grade B-cell, 82 peripheral T-cell, 7 high-grade non-B-cell, non-T-cell, and 7 hairy-cell leukemia) for EBV gene expression by immunohistologic procedures using monoclonal antibodies to EBV latent, immediate early, and replicative infection antigens. Transformation-associated EBV latent membrane protein 1 (LMP 1) was detected in 13 (6%) NHL, comprising 4 (4%) high-grade B-cell, 8 (10%) peripheral T-cell, and 1 non-B-cell, non-T-cell lymphomas. Anaplastic large-cell lymphoma of T-cell type was consistently LMP 1-negative. EBV nuclear antigen 2 was demonstrated in only three (1%) cases. Induction of replication as defined by expression of the immediate early BamHI Z leftward reading frame 1 (BZLF1) protein was detected in five cases, but early (EA) and late (VCA and MA) lytic cycle antigens were only found in two cases and in one case, respectively. The presence of EBV was confirmed by in situ DNA hybridization in 9 of 11 EBV antigen-positive lymphomas. This study shows the surprisingly frequent presence of EBV in peripheral T-cell NHL in European patients without pre-existing overt immunodeficiency. Interestingly, most sporadic B-cell NHL are not associated with the virus. Furthermore, the usefulness of selected monoclonal antibodies for the routine immunohistological diagnosis of EBV infection was confirmed.