Effects of maternal exercise on fetal activity in late gestation

Sixty malignant non-Hodgkin's lymphomas originating in the upper aerodigestive tract have been analyzed for their cytologic type, immunophenotype and association with the Epstein-Barr virus (EBV). The majority of these tumors were B-cell lymphomas of blastic cytology (78%) with the exception of lymphomas in the parotid gland. Large B-cell lymphomas were the most frequent encountered in the sinonasal region and Waldeyer's ring. Twelve lymphomas were of T- or T/NK (natural killer)-cell lineage. They were in the nasal cavity and the paranasal sinuses (4), the tonsil (5), and the oral cavity (3). Epstein-Barr sequences were detected in five angiocentric T/NK-lymphomas, one peripheral T-cell lymphoma, one lymphoma of lymphomatoid granulomatosis type, one large B-cell lymphoma, and in a lymphoroliferative disorder in an HIV-positive patient. These results suggest that EBV is not involved in lymphomagenesis of B-cell tumors, but is associated with angiocentric T/NK-cell lymphoma in the upper aerodigestive tract.     

Hemophagocytic syndrome in five patients with Epstein-Barr virus negative B-cell lymphoma

BACKGROUND: The recent recognition of the association of Epstein-Barr virus (EBV) with T-cell/natural killer cell (T/NK-cell) lymphoma has documented that particular types of EBV-containing T/NK-cell lymphoma are frequently complicated by hemophagocytic syndrome (HPS). This observation suggests that both EBV and proliferating T/NK-lymphoma cells play significant roles in the development of HPS. Cytokines released from neoplastic T cells are presumed to account for the activation of macrophages, which is followed by a complex cascade of cytokine production, resulting in full-blown HPS. Five patients with B-cell lymphoma complicated by HPS were studied for elevated serum cytokines, the association of EBV, and CD25 expression of lymphoma cells; the aim of this study was to verify whether the mechanisms of HPS development hypothesized for T/NK-cell lymphoma also operate in B-cell lymphoma. METHODS: Sera were analyzed for the presence of inflammatory and immunoregulatory cytokines. Flow cytometry, immunohistology (IH), in situ hybridization (ISH), polymerase chain reaction (PCR), and Southern blot analysis were performed using bone marrow aspirates, biopsy specimens, and autopsy specimens. RESULTS: Immunophenotypic and Southern blot studies verified that the lymphoma cells of all five patients were of B-cell lineage. Bone marrow aspirates demonstrated histiocytosis with extensive hemophagocytic activity. Marked elevation of serum cytokines and expression of CD25 were observed in all five patients. However, the results of PCR, ISH using EBER1 probe, and IH for latent membrane protein indicated that these lymphoma cells were free of EBV infection. CONCLUSIONS: In patients with B-cell lymphoma, EBV infection is not necessarily required for the initiation of HPS. In this article, the pathogenesis of HPS assumed to be operative in B-cell lymphoma is discussed with reference to T/NK-cell lymphoma complicated by HPS.     

CD56+ putative natural killer cell lymphomas: production of cytolytic effectors and related proteins mediating tumor cell apoptosis?

Apoptosis is a regulated form of cell death that may be triggered by natural killer (NK) or cytotoxic T cells, which effect target cell lysis by cytolytic effector and related proteins through complex intracellular signals. This study was aimed to investigate whether there is selective expression of these cytolytic markers in the putative NK-cell lymphomas and whether there is correlation with zonal tumor cell death in these tumors. Expression of the cytolytic effectors perforin, granzyme B9, and the granule membrane protein TIA1 were examined in 24 putative NK-cell lymphomas, 18 postthymic T-cell lymphomas (one case CD8+ CD56+ and three anaplastic large cell lymphomas (ALCL), three T-lymphoblastic lymphomas, and 20 B-cell lymphomas. Nineteen (79%) putative NK-cell lymphomas expressed perforin, and all 24 cases expressed granzyme B9 and TIA1. The only CD8+ CD56+ postthymic T-cell lymphoma also expressed all three cytolytic markers, two CD8- ALCL expressed TIA1; other postthymic T-cell, T-lymphoblastic, and B-cell lymphomas were consistently negative. There was strong correlation between percentage perforin-positive cells and zonal tumor cell death. Angioinvasion, in contrast, was present only in a proportion (37%) of these lymphomas despite the frequent presence of zonal tumor cell death (71%). We propose that cytolytic effector and related proteins produced by putative NK and some CD8+ CD56+ postthymic T-cell lymphomas, probably in conjunction with other mechanisms, may effect massive tumor cell apoptosis. The frequent expression of cytolytic effector markers in the CD2+ surface CD3- CD56+ putative NK-cell lymphomas lends further support to their probable NK cell origin.     

Role of cytochrome P450c17 in polycystic ovary syndrome

Epstein-Barr virus is universally associated with endemic Burkitt's lymphoma (BL) and undifferentiated nasopharyngeal carcinoma and can be detected in a significant proportion of cases of Hodgkin's disease (HD) and peripheral T-cell lymphoma, but only rarely in sporadic B-NHL. The frequency of EBV-positivity in certain neoplasms shows important geographic variations. Both HD and sporadic BL from Latin America have shown higher rates of EBV-association than cases from Western countries. In T-NHL, the frequency of EBV-positivity is influenced by the site of the primary tumor and the phenotype of the neoplastic cells. Nasal and nasal-type T-NHL, which show a T/NK-cell phenotype with expression of CD56 are virtually always EBV-associated, whereas only a proportion of nodal, gastrointestinal and pulmonary T-NHL are EBV-infected. A recent investigation of primary intestinal lymphomas of Mexican origin demonstrated EBV-positivity in all examined cases of T-NHL and BL and a proportion of other B-NHLs. The presence of EBV was independent of the presence or absence of enteropathy. Two of 6 cases studied showed CD56 expression. The high rate of EBV-positivity independent of histologic subtype is in contrast to the low to intermediate rates of EBV-positivity found in cases of intestinal T-NHL from Western countries and indicates that geographic differences in the frequency of EBV-association of lymphoid neoplasms might also extend to a fraction of peripheral T-cell lymphomas.     

Uncommon clinical presentation of a lymphocytic lymphoma of intermediate differentiation in a patient with systemic sclerosis

The association of systemic sclerosis (SSc) and non-Hodgkin lymphoma is a rare event and its pathogenetic mechanism remains to be clarified. We describe a previously unreported association of SSc with a lymphocytic lymphoma of intermediate differentiation (IDL), involving the gastrointestinal tract, gallbladder and one salivary gland. Whereas the morphological, immunological and cytogenetic features were typical of IDL, the extensive extranodal involvement and the association with an autoimmune disorder were suggestive of two other lymphomas of mantle lineage: mucosa-associated lymphoid tissue (MALT) lymphoma and monocytoid B-cell lymphoma (MBCL).     

Prognosis of the skin UV-incidence increase in Poland

We studied the morphologic and immunohistochemical features of 10 peripheral T-cell lymphomas of a cytotoxic phenotype (CD3+/CD4-/CD8+), encountered among 98 peripheral T-cell lymphomas (PTCLs). Nine tumors were positive for both cytotoxic molecules, namely perforin (Pf) and granzyme B (GrB), and strong positivity was seen in the majority of the malignant cells. We also studied the expression of these molecules in 92 other cases of T-cell and natural killer (NK) cell neoplasms; 18 anaplastic large cell lymphomas (ALCLs); 63 CD4+ PTCLs; 10 CD56+ nasal lymphomas; and 1 NK-cell leukemia. Most of the CD4+ PTCLs (62 of 63) were negative for GrB, but all of the nasal lymphomas and the NK cell leukemia were positive for both Pf and GrB. Variable expression was seen among the 18 ALCLs. Within the 10 CD8+ PTCLs, 4 involved the skin, 3 of which were diagnosed as primary cutaneous lymphomas. Five patients died within 1 year of diagnosis. According to the Revised European-American Classification of Lymphoid Neoplasms, seven cases were categorized as "PTCL, unspecified," and three as "angioimmunoblastic T-cell lymphoma," "adult T-cell lymphoma/leukemia," or "small cell lymphoma," respectively. Three cases had characteristic morphologic features consisting of large lymphomatous cells with massive necrosis and nuclear fragmentation. Epstein-Barr virus mRNA was detected by in situ hybridization in three cases. Although the degree of apoptosis varied, apoptotic cells were detected in all cases by terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate-biotin nick end labeling. We conclude that CD8+ PTCLs are relatively rare, often involve extranodal sites, have an aggressive clinical course, and are often associated with Epstein-Barr virus. Compared with ALCLs, which have recently been considered as neoplasms of cytotoxic T-cells, we think that CD8+ PTCLs are more lineage-specific neoplasms of mature, cytotoxic, T lymphocytes.     

Epstein-Barr virus in malignancies in renal transplant recipients in Japan

A role for Epstein-Barr virus (EBV) in the development of malignancies including lymphomas, and carcinoma of the stomach, nasopharynx, thymus and salivary gland is suggested. It is indicated that EBV evokes polyclonal-B-cell-proliferative diseases in immunocompromised hosts, such as transplant patients, which results in monoclonal malignant lymphomas. The suppression of immune functions in these patients is thought to lead to incomplete elimination of the cells expressing EBV latent infection genes. To examine the etiological role of EBV in the development of malignancies following renal transplant in Japan, 42 malignancies in 1744 cases of renal transplant were studied for the presence and type of EBV. The polymerase chain reaction revealed that 5 malignancies were positive for EBV, all type A: 2 of 2 cases of non-Hodgkin's lymphoma (NHL), 2 of 8 cases of gastric adenocarcinoma of the common type, and 1 of 2 cases of gastric plasmacytoma. In situ hybridization revealed positive signals in the nucleus of tumor cells in 2 cases of NHL and 1 of plasmacytoma. Positive signals were found in the small lymphoid cells but not in the tumor cells in 2 cases of gastric carcinoma. On the basis of these findings, a role for EBV in the development of malignancies in renal transplant patients is unlikely except for lymphoid neoplasias.     

Primary cardiac lymphoma. No evidence for an etiologic association with Epstein-Barr virus

OBJECTIVES: To report two cases of primary cardiac lymphoma, a rare extranodal lymphoma with an unknown pathogenesis, and to compare them to secondary B-cell cardiac lymphoma. DESIGN: Clinicopathologic features are described, using histologic and immunophenotypic examinations. The Epstein-Barr virus genome is detected by in situ hybridization. PATIENTS: Of 80 autopsied cases of malignant lymphoma identified at Nagoya (Japan) University Hospital, two patients with primary cardiac lymphoma and five patients with secondary cardiac B-cell lymphoma were selected. RESULTS: None of the seven selected cases showed immunodeficiency, autoimmune disorders, or chronic inflammatory processes. Primary cardiac lymphomas had B-cell phenotypes with mu and lambda chain monoclonality. Immunostaining for Epstein-Barr virus (latent membrane protein-1) and Epstein-Barr virus-encoded RNA-1 in situ hybridization did not demonstrate an association of these lymphoma with Epstein-Barr virus infection. The majority of secondary cardiac B-cell lymphomas were extranodal lymphomas and extranodal or serosal involvement was more prominent than nodal involvement. CONCLUSION: These findings suggest that primary cardiac lymphoma, unlike pyothorax-associated pleural lymphoma, appears to have no association with chronic inflammation or Epstein-Barr virus infection.     

Disclosure of concerns by hospice patients and their identification by nurses

Immunohistologic studies were performed to identify the phenotype and distribution of neoplastic lymphocytes in the spleens of BLV-negative animals examined by PCR and diagnosed as having sporadic bovine leukosis. Tumor cells from three cases of sporadic bovine leukosis were identified as of B-cell lineage. Tumor cells from three additional cattle were identified as CD3+ CD4- CD8+, CD3+ CD4- CD8-, and CD3+ CD4- WC1+, respectively. The last case was diagnosed as a gamma/delta T-cell lymphoma. Differences in morphology proliferative characteristics were recognized between B- and T-cell type lymphomas. The tumor cells in B-cell type lymphoma were characterized as follows: medium or large in size, round or polymorphic nucleus with rough chromatin with some tumor cells containing a convoluted nucleus. These tumor cells of B-cell type lymphoma were present in the red pulp and periarteriolar lymphoid sheath. Tumor cells of the T-cell type lymphoma were uniformly smaller than B-cell type and present around arteries or replaced red pulp of the spleen.     

Lymphomas in patients with Sjogren's syndrome are marginal zone B-cell neoplasms, arise in diverse extranodal and nodal sites, and are not associated with viruses

The occurrence of non-Hodgkin's lymphoma (NHL) is the most serious complication of Sjogren's syndrome (SS). We performed a study of 16 NHLs occurring in patients with an underlying SS. These lymphomas arose not only in salivary glands (7 cases) but also in other mucosal extranodal sites (the stomach [4 cases], the lung [3 cases], the skin [3 cases], the buccal mucosa [1 case], the thymus [1 case]) and in nodal sites (8 cases). Low-grade marginal zone lymphomas (MZL) were diagnosed in 12 of the 16 patients, 9 of mucosa-associated lymphoid tissues (MALT) type in mucosal sites and 3 exclusively nodal. The 4 other patients presented with a high-grade B-cell lymphoma that was probably a histological transformation of an underlying low-grade MZL at least in 3 of the cases involving skin, stomach, and parotid, respectively. A t(14;18) translocation was detected in 1 of 8 lymphomas tested. We detected serum anti-p53 antibodies in 2 of the 14 studied patients. p53 protein was detected in 1 of 11 lymphomas tested. LMP protein and Eber RNAs of Epstein-Barr virus (EBV) were not detected in the 16 NHL biopsies. Using polymerase chain reaction, EBV was never detected except in 1 of 4 parotid lymphomas. No human T-lymphotropic virus 1 or human herpes virus 8 DNAs were detected in NHL biopsies. None of the patients had hepatitis C virus infection found using serological methods. Chemotherapy was usually efficient. In conclusion, lymphomas occurring in patients with an underlying SS are in most cases MZL. These lymphomas are not associated with viruses known to be present in other types of lymphomas. Some of the translocations or mutations of oncogenes or antioncogenes described in other lymphomas are detected in SS-associated lymphomas.     

CD30 antigen expression in florid immunoblastic proliferations. A clinicopathologic study of 14 cases

Reactive immunoblastic proliferations may be confused with certain types of non-Hodgkin's lymphoma and Hodgkin's disease on morphologic grounds. In addition, a characteristic antigen, CD30 (Ki-1; BerH2) on these neoplastic entities may be observed in morphologically atypical yet reactive florid immunoblastic proliferations such as those associated with acute infectious mononucleosis. Although it has been documented, a large series determining the frequency and extent of CD30 antigen expression on a variety of nonneoplastic immunoblastic proliferations is lacking. The authors studied 14 florid immunoblastic proliferations (9 in lymph nodes and 5 in tonsils) for CD30 antigen expression and for B- and T-cell paraffin markers. In situ hybridization to determine the presence of Epstein-Barr virus (EBV) genomes also was performed. Cases were classified into monospot-positive acute infectious mononucleosis (4 cases), EBV-related lymphoproliferative disorder suggestive of acute infectious mononucleosis (5 cases), and other etiologies (5 cases). CD30 Antigen expression was found on the immunoblasts in cases from all three categories and overall in 9 (64%) of 14 specimens. CD30 reactivity in the positive cases varied from occasional to numerous positive cells; 4 samples (3 EBV-related lymphoid proliferations and 1 vaccine-related lymphadenopathy) had numerous CD30-reactive immunoblasts. Expression of CD30 antigen on B or T cells and prominence of B or T cells within a proliferation were variable. Significant "atypia" of immunoblasts was found only in EBV-related disorders and correlated with B-cell prominence of the infiltrate. Appropriate clinical correlation and ancillary laboratory data are necessary to assist in differentiating these CD30(+)-reactive disorders from similar-appearing malignant lymphomas. Most important, a fresh tissue sample should be procured and adequately processed to allow for comprehensive determination of clonality and cellular lineage.     

Detection of Epstein-Barr virus in transformations of low-grade B-cell lymphomas after fludarabine treatment

Fludarabine is a highly effective chemotherapeutic agent for chronic lymphocytic leukemia/small lymphocytic lymphoma and is also active in other B-cell lymphoproliferative disorders. Although highly efficacious in destroying the malignant B-cells, fludarabine also causes T-cell lymphopenia and immunosuppression. We present five patients given fludarabine for low-grade B-cell lymphoproliferative disorders who showed transformation of the primary neoplasm to a higher grade tumor. Immunohistologic antibody studies were performed on paraffin-embedded tissue sections of the initial tissue (when available) and on the follow-up biopsy specimens for CD20, CD3, CD45RO, CD43, CD30, CD15, and latent membrane protein (LMP-1) for Epstein-Barr virus (EBV). The initial diagnoses in these five patients included chronic lymphocytic leukemia/small lymphocytic lymphoma (three cases), follicle center lymphoma (one case), and Waldenstrom's macroglobulinemia (one case). All of the follow-up biopsy specimens showed scattered Hodgkin's-like cells, and two of the five also showed foci of large-cell transformation. The Hodgkin's-like cells showed CD30 immunoreactivity in four of the five cases and CD15 immunoreactivity in three of the five. Strong immunoreactivity of the large, atypical, Hodgkin's-like cells for LMP-1 of EBV was noted in four cases; in the remaining case, this finding was equivocal. In situ hybridization for EBV-encoded RNA was positive in four of the five cases. Molecular studies by polymerase chain reaction (PCR) showed the presence of EBV in three of the five cases. PCR for detection of immunoglobulin heavy chain demonstrated identical monoclonal rearrangements in the original lymphoma and transformation in one case with available material. The CD4 lymphocyte count in each patient was less than 550/microL, indicating cellular dysfunction. Transformation of low-grade non-Hodgkin's lymphomas after fludarabine therapy might be associated with EBV and severe immunosuppression.     

Comparing neural networks in the discrimination of benign from malignant lower urinary tract lesions

BACKGROUND: Angiocentric cutaneous T-cell lymphomas of childhood (ACTCLC) are an unusual type of T-cell lymphomas that present with a vesiculopapular eruption mimicking hydroa vacciniforme. Most patients have been children from Asia and Latin America. OBJECTIVE: The purpose of this study was to describe four cases of ACTCLC; to discuss its clinical, histopathologic, and immunohistochemical features; to consider its possible relationship to the Epstein-Barr virus (EBV); and to clarify its classification within the spectrum of angiocentric lymphomas. METHODS: The clinical, histopathologic, and immunohistochemical features of four cases of ACTCLC were identified and analyzed. In addition in situ hybridization for EBV was performed in all cases. RESULTS: The clinical features were similar to previous cases reported under different names, such as hydroa-like lymphomas, edematous, scarring vasculitic panniculitis. Histologically, all showed angiocentric infiltrates composed mainly of T cells. In all cases there were variable numbers of CD30+ cells. The EBV was present in three of the cases. CONCLUSION: ACTCLC is a distinct type of T-cell lymphoma. It affects mainly children, and the EBV appears to play a role in the pathogenesis of this disease.     

The t(11;18)(q21;q21) chromosome translocation is a frequent and specific aberration in low-grade but not high-grade malignant non-Hodgkin's lymphomas of the mucosa-associated lymphoid tissue (MALT-) type

Primary extranodal malignant non-Hodgkin's lymphoma arising from the mucosa-associated lymphoid tissue (MALT-type lymphoma) represents a subtype of B-cell lymphoid malignancies with distinct clinicopathological features and is often associated with a favorable prognosis. Unlike the situation in nodal non-Hodgkin's lymphoma of B-cell lineage, few data are still available concerning the chromosomal constitution of MALT-type lymphomas. Until now, cytogenetic data from 29 low-grade MALT lymphomas with karyotypic alterations have been reported from different institutions, and virtually no data were available for high-grade MALT-type lymphomas. We have analyzed the cytogenetics of 44 MALT lymphomas arising in the stomach, parotid gland, thyroid gland, lung, breast, and conjunctiva. Clonal chromosome aberrations have been detected in 13 of 20 (65%) low-grade and 20 of 24 (83%) high-grade tumors. More than half of the low-grade lymphomas with abnormal karyotypes (7 of 13 cases, 53%) displayed clonal t(11;18)(q21;q21), thus specifically associating this translocation with MALT-type lymphomas for the first time in a larger series. In contrast, t(11;18) was not found in a single case of 20 high-grade MALT-type lymphomas with abnormal karyotypes, nor were translocations t(14;18) or t(3;14), characterizing about 10-35% of primary nodal large cell lymphomas. Instead, these lymphomas were associated with t(8;14)(q24;q32) in three cases, frequent deletions in the long arm of chromosome 6, and partial or whole gains of chromosomes 3, 7, 17, 18, and 21.     

Differential expression of BCL-6, CD138/syndecan-1, and Epstein-Barr virus-encoded latent membrane protein-1 identifies distinct histogenetic subsets of acquired immunodeficiency syndrome-related non-Hodgkin's lymphomas

This study was aimed at defining the histogenesis of the pathologic spectrum of acquired immunodeficiency syndrome-related non-Hodgkin's lymphomas (AIDS-NHL), including AIDS-related small noncleaved cell lymphoma (AIDS-SNCCL), AIDS-related large noncleaved cell lymphoma (AIDS-LNCCL), AIDS-related large cell immunoblastic lymphoma plasmacytoid (AIDS-IBLP), and AIDS-related primary effusion lymphoma (AIDS-PEL). Forty-six cases of AIDS-NHL were investigated for the expression pattern of BCL-6, a protein specifically expressed by germinal center (GC) B-cells, and CD138/syndecan-1 (syn-1), a marker of post-GC B-cell differentiation. Expression of BCL-6 and syn-1 segregated two major phenotypic patterns among AIDS-NHL: (1) the BCL-6+/syn-1- pattern associated with AIDS-SNCCL and AIDS-LNCCL; (2) the BCL-6-/syn-1+ pattern associated with AIDS-IBLP and AIDS-PEL. Among systemic AIDS-NHL infected by Epstein-Barr virus (EBV), expression of the EBV-encoded latent membrane protein-1 (LMP-1) preferentially associated with the BCL-6-/syn-1+ profile. Analysis of nonneoplastic lymph nodes showed that the two phenotypic patterns detected in AIDS-NHL correspond to physiologic stages of B-cell development, i.e., GC B-cells (BCL-6+/syn-1-) and preterminally differentiated post-GC B-cells (BCL-6-/syn-1+). Thus, BCL-6+/syn-1- AIDS-NHL reflects a GC stage of differentiation, whereas AIDS-NHL which are BCL-6-/syn-1+, and LMP-1+ when infected by EBV, derive from B cells that have entered post-GC plasmacell differentiation. These findings are relevant for the pathogenesis and differential diagnosis of AIDS-NHL.     

Lung cancer: intermittent irradiation synchronized with respiratory motion--results of a pilot study

Pyothorax-associated lymphoma (PAL) is a newly-described entity developing several decades after artificial pneumothorax treatment for pulmonary or pleural tuberculosis. It is known to be associated with Epstein-Barr virus (EBV) with constant expression of the two latent membrane proteins: latent membrane protein (LMP)-1 and EBV-associated nuclear antigen (EBNA)-2. We are reporting three new cases of PAL. All of the tumours were of B-cell lineage and classified as large-cell diffuse lymphomas according to the International Working Formulation for the Classification of Lymphomas. The EBV genome was detected in two of the cases with LMP-1 and EBNA-2 expression. No EBV could be detected in the third case suggesting that different mechanisms may be involved in the pathogenesis of the disease. Body cavity-based high grade lymphomas (BCBL) represent a new disease, developing mainly in human immunodeficiency virus (HIV) infected patients: the tumoural cells often contain both human herpes virus (HHV)-8 (or Kaposi's sarcoma herpes virus) and EBV genomes, suggesting that these viruses might co-operate in the pathogenesis of the disease. The pleural location and the association of EBV have led to speculation that PAL could also be related to HHV-8 infection. However, no HHV-8 genome could be detected in any of the 14 tested cases already reported in the literature nor in the two cases we studied (one EBV-positive and one EBV-negative), suggesting that PAL and BCBL are two different entities.     

Anorexia and lycanthropy ++: grandiosity and fall

Epstein-Barr virus (EBV) is linked to a spectrum of human diseases including epithelial and lymphoid malignancies in which it exists predominantly in a latent state. EBV is capable of establishing replicative infection at oropharyngeal and genital sites. Replicative EBV infection also occurs in oral hairy leukoplakia, in EBV associated lymphoproliferative disorders, and to a minor degree in nasopharyngeal carcinomas. Recent evidence also suggests that EBV replication, also, may be associated with AIDS related lymphomas and Hodgkin's disease. However it is widely believed that virus in circulating B-lymphocytes and in B-cell malignancies is stringently latent. We now show that by Southern blot analysis we can detect replicative forms of virion DNA in 14.5% (8 of 55) of EBV-positive Burkitt's lymphoma biopsies. This may be the explanation for the elevation of the titres of lytic cycle EBV antigens that is associated with presentation and relapse of EBV associated Burkitt's lymphoma.