Epstein-Barr virus (EBV) in extranodal T-cell non-Hodgkin's lymphomas (T-NHL). Identification of nasal T-NHL as a distinct clinicopathological entity associated with EBV

Nasal-type extranodal natural killer/T-cell lymphoma presenting with a mass on the buttock: A case report

RATIONALE

Nasal-type extranodal natural killer (NK)/T-cell lymphoma is a highly unusual disease with no standard curative managements yet. Our focus is to emphasize a very rare case of nasal-type extranodal NK/T-cell lymphoma with onset of the mass on the buttock successfully operated by combination of surgical excision together with chemotherapy. The management of these unique cases is of great clinical guiding significance.

PATIENT CONCERNS

A 20-year-old woman presented with a 2-month history of continuous and progressive severe pain on her left buttock. Since December 2017, the patient developed nasal congestion, accompanied with mild pain in the left eye, and new subcutaneous nodules on both cheeks.

DIAGNOSIS

Postoperative pathology confirmed the diagnosis of extranodal NK/T cell lymphoma. This is an extremely rare presentation of nasal-type NK/T-cell lymphoma.

INTERVENTIONS

The patient underwent enlarged resection of the tumor on the buttock. After the diagnosis of extranodal NK/T-cell lymphoma was established, the patient received chemotherapy and autologous hematopoietic stem cell transplantation.

OUTCOMES

The patient's symptoms improved significantly after the surgery, and the postoperative period was uneventful at the 1-year follow-up visit. There were no complications associated with the operation and adjuvant therapies during the follow-up period.

LESSONS

Taken together, the lesion's clinical features, imaging results, and pathological characteristics are unique. Extranodal NK/T-cell lymphoma, although rare, should be part of the differential diagnosis when the patient presents with the mass on the buttock. We recommend enlarged excision of the extranodal lymphoma. Combined of surgical excision of the extranodal lymphoma, chemotherapy and autologous hematopoietic stem cell transplantation are good choice for proper treatment.

Primary cutaneous T-cell lymphomas: a review

Primary cutaneous T-cell lymphomas (CTCLs) represent a number of extranodal lymphomas arising from a malignant population of lymphocytes in the skin, with the most common type being mycosis fungoides (MF) representing half of all primary CTCLs. Despite advances in immunohistochemistry and molecular methodology, significant diagnostic challenges remain due to phenotypic overlap of primary CTCLs with several inflammatory dermatoses, secondary lymphomas, among other conditions. Clinical features such as presentation and morphology, staging, histology, immunophenotype and molecular features must be considered in detail before a diagnosis is made in order to minimise false-positive, false-negative and indeterminate diagnoses. Herein, we review primary CTCLs, including epidemiological data, a brief summary of clinical presentations, immunophenotype, molecular signatures and differential diagnoses.

Extranodal natural killer/T-cell lymphoma, nasal type, involving the skin, misdiagnosed as nasosinusitis and a fungal infection: A case report and literature review

The present study reports a case of extranodal natural killer (NK)/T-cell lymphoma, nasal type, involving the skin. The clinical manifestations, pathological characteristics, treatment and prognosis of the case were analyzed to improve the clinical diagnosis and treatment for this disease. The patient was a 56-year-old male, presenting with dark red nodules and plaques that had been visible on the nose for half a year. Based on the skin lesions and histopathological and immunohistochemical examination results, the patient was diagnosed with extranodal NK/T-cell lymphoma, nasal type. This disease has unique histopathological and immunohistochemical features and a high malignancy. The condition tends to be misdiagnosed and has a poor prognosis, but seldom involves the skin. In the present case, only radiotherapy was performed, with no relapse occurring within 6 months.

Pyoderma Gangrenosum Associated with Nasal Septal Perforation, Oropharyngeal Ulcers and IgA Paraproteinemia

We report a case of pyoderma gangrenosum (PG) associated with nasal septal perforation, pharyngeal ulcers and IgA paraproteinemia. A 28-year-old woman first developed painful undermined ulcers on her perianal, inguinal and axillary areas when she was 22 years old. Histological findings from the cutaneous ulcers showed dermal and epidermal infiltrate of neutrophils, which was compatible with PG. Laboratory examinations did not detect any associations of systemic diseases other than polyclonal IgA paraproteinemia. Nasal fiberscopy revealed septal perforation and multiple ulcers on her pharynx. The biopsy specimen from the pharyngeal ulcers showed a polymorphous cellular infiltrate without necrotizing vasculitis or granuloma. However, there were no atypical lymphocytes that are typically seen in nasal NK/T lymphoma. By immunohistochemical analysis, the infiltrated lymphocytes were proved to be T cells and Epstein-Barr virus encoded RNA (EBER) was not detected. No pulmonary or renal lesions resembling Wegener's granulomatosis were found. Taken together, the nasal septal perforation was considered as nasal involvement of PG.

Gene expression profiling of non-hodgkin lymphomas

BACKGROUND

Chromosomal translocations are genetic aberrations associated with specific non-Hodgkin lymphoma (NHL) subtypes. This study investigated the differential gene expression profile of Egyptian NHL cases based on a microarray approach.

MATERIALS AND METHODS

The study included tissue samples from 40 NHL patients and 20 normal lymph nodes used as controls. Total RNA was extracted and used for cDNA microarray assays. The quantitative real time polymerase chain reaction was used to identify the aberrantly expressed genes in cancer.

RESULTS

Significant associations of 8 up-regulated and 4 down-regulated genes with NHL were observed. Aberrant expression of a new group of genes not reported previously was apparent, including down-regulated NAG14 protein, 3 beta hydroxy-delta 5-c27 steroid oxi-reductase, oxi-glutarate dehydrogenase (lipo-amide), immunoglobulin lambda like polypeptide 3, protein kinase x linked, Hmt1, and caveolin 2 Tetra protein. The up-regulated genes were Rb binding protein 5, DKFZP586J1624 protein, protein kinase inhibitor gamma, zinc finger protein 3, choline ethanolamine phospho-transferase CEPT1, protein phosphatase, and histone deacetylase-3.

CONCLUSIONS

This study revealed that new differentially expressed genes that may be markers for NHL patients and individuals who are at high risk for cancer development.

Low frequency of Epstein Barr virus association and high frequency of p53 overexpression in an Argentinean pediatric T-cell lymphoma series

T-cell non-Hodgkin's lymphomas (NHLs) represent 10% to 15% of all diagnosed lymphomas in Western countries. Various geographic frequencies of T-cell NHL have been documented, in part reflecting increased exposure to pathogenic factors such as Epstein-Barr virus (EBV). Our aims were to assess EBV and p53 expression in Argentine pediatric T-cell lymphoma and to correlate them with patients' survival. Epstein-Barr encoded RNAs (EBERs) in situ hybridization and LMP1 and p53 immunohistochemical staining were performed on formalin-fixed paraffin-embedded lymph node biopsies from 25 pediatric T-lymphoma patients. In 17 of 25 samples good-quality DNA was obtained, and EBER polymerase chain reaction was assessed to confirm in situ hybridization and immunohistochemical results. Epstein-Barr virus expression was found in 8.0% of cases. p53-positive staining was distributed in 92% of pediatric cases. Kaplan-Meier survival analysis showed that neither EBV nor p53 expression was statistically significantly associated with event-free survival. Our data showed a low frequency of EBV association with pediatric T-cell lymphoma. It seems that p53 plays an important role in proliferation in our studied population, since it is overexpressed in 92% of T-cell lymphoma cases.

Nasal-type NK/T-cell lymphoma presenting as hemophagocytic syndrome in an 11-year-old Mexican boy

Recently established by the World Health Organization classification, "nasal" and "nasal-type" NK/T-cell lymphoma arise from natural killer (NK) cells. They have distinct clinicopathologic features, specific genotype and phenotype, and a high association with Epstein-Barr virus infection. Nasal-type NK/T-cell lymphoma arise from extranasal sites including skin, soft tissue, gastrointestinal tract, liver, spleen, testes, lung, and central nervous system. Most cases are reported from Asia and South America in adults. There are very few cases reported in the pediatric age group. We report an 11-year-old child with extranodal nasal-type NK/T-cell lymphoma presenting as hemophagocytic syndrome and multiorgan system failure with fatal outcome.

Human herpesvirus 7 detection by quantitative real time polymerase chain reaction in primary cutaneous T-cell lymphomas and healthy subjects: lack of a pathogenic role

BACKGROUND

Primary cutaneous T-cell lymphomas (CTCLs) are a heterogeneous group of lymphomas where the tumour population emerges within a multiple subclone pattern. Mycosis fungoides (MF) and Sézary syndrome (SS) are characterized by the expansion of clonal CD4+/CD45RO+ memory T cells. Lymphomatoid papulosis (LyP) is a chronic, lymphoproliferative disorder included in the CD30+ primary CTCL spectrum. Several studies have suggested a role of viral infection for super-antigenic activation of T lymphocytes; however, evidence of their association with CTCLs is still lacking. Human herpesvirus (HHV) 7 is a CD4+ T-lymphotropic herpesvirus; its restricted cellular tropism and the ability to induce cytokine production in infected cells could make it an important pathogenic cofactor in lymphoproliferative disorders.

OBJECTIVES

To investigate the presence of HHV7 DNA on CTCL and healthy skin donors (HD).

METHODS

We used quantitative real time polymerase chain reaction to evaluate the potential pathogenic role of HHV7.

RESULTS

Twenty-seven of 84 (32.1%) HD were positive for HHV7 DNA. Twenty-one of 148 (14.2%) patients with CTCLs were positive for HHV7 DNA: nine of 39 (23.1%) SS, six of 14 (42.9%) CD30+ CTCLs and six of 24 (25.0%) LyP, and HHV7 DNA was negative in all 71 patients with MF.

CONCLUSIONS

These results seem to exclude a pathogenic role of HHV7 in CTCLs, suggesting the possibility of skin as a latency site.

[Prevalence of Epstein-Barr virus in non-Hodgkin's lymphomas in central region of Tunisia]

The purpose of this study was to evaluate the prevalence of EBV in non-Hodgkin's lymphomas occuring in non-immunocopromised patients in Tunisia through a series of 126 cases. EBV was investigated by EBER oligonucleotide in situ hybridization (ISH) and LMP1-immunohistochemistry. Serological study of EBV has been performed before therapy in 28 patients. EBV was detected in tumor cells by ISH in 28/126 (22.2%) cases. Variable proportions of tumor cells were positive. LMP1 was identified in only 8 cases. EBV was more frequently observed in T-cell lymphomas (9/24 patients; 37.5%) than in B-cell lymphomas (19/102 patients; 18.6%) (p=0.04). There was a strong relationship between EBV and small intestine lymphomas (6/8 patients; 75%) and T/NK nasal type lymphomas (3/3 patients; 100%). EBV serological reactivation was noted in 7/13 patients in clinical stages III/IV and in only 1/10 patients in stages I/II (p=0.03). In conclusion, the prevalence of EBV in Tunisian non-Hodgkin's lymphomas is low but variable depending on the histological type and anatomical location with a predilection for small intestine and nasal lymphomas.

Viruses and lymphoma/leukaemia

Viruses of the retrovirus and herpesvirus families are aetiological agents of human leukaemias and lymphomas. The human T-cell leukaemia virus type 1 causes adult T-cell leukaemia and the Epstein-Barr virus is associated with Burkitt's lymphoma, lymphomas in immunosuppressed people, and Hodgkin lymphoma. The discovery of human herpesvirus type 8 has led to the identification of a rare and unusual group of virus-associated lymphoproliferative diseases. Individuals infected with the human immunodeficiency virus are at greatly increased risk of developing lymphoma but here the mechanism of lymphomagenesis is indirect. Recent data suggest that hepatitis C virus infection is also associated with an increased incidence of lymphoma, whereas data relating to SV40 remain controversial.

Nasal-type extranodal natural killer/T-cell lymphomas: a clinicopathologic and genotypic study of 42 cases in Singapore

We studied the clinicopathologic features of 42 cases of nasal-type extranodal natural killer (NK)/T-cell lymphoma in Singapore and compared our findings with other series reported in the Asian and Western populations. A panel of immunohistochemical stains, which included CD2, CD3, CD4, CD8, CD56, T-cell intracellular Antigen-1 and granzyme B, and in situ hybridization for Epstein-Barr virus encoded RNA (EBER) were performed. Polymerase chain reaction for T-cell receptor-gamma gene rearrangement using both gel and capillary electrophoresis were evaluated to determine the proportion of tumors which are of true T-cell lineage. We also studied the functional status of the overexpressed p53 protein in these lymphomas by correlating p53 expression with its downstream target protein, p21. In all, 31 out of 42 cases presented in the upper aerodigestive tract. The other sites of involvement included gastrointestinal tract, skin, soft tissue, testis, liver, spleen, bone marrow and brain. The tumors displayed characteristic morphologic features. In situ hybridization for EBER was detected in 41 out of 42 cases (97.6%). The only significant adverse prognostic factor identified was an International Prognostic Index of two or more. A significantly higher proportion of the tumors (27%), compared to previous studies, demonstrated monoclonal T-cell receptor-gamma gene rearrangement. There was, however, no difference in survival or clinicopathologic features between the true NK-cell tumors and their T-cell counterparts. Overexpression of p53 was present in 40% of the cases, but no significant difference in survival rate was detected in patients with p53 overexpression and there was no association between p53 overexpression with large cell morphology, and advanced stage of disease. These findings suggest that molecular aberrations other than those of the p53 pathway may be operative in the pathogenesis of this malignancy.

Classification of cytotoxic T-cell and natural killer cell lymphomas

Mature or peripheral T-cell lymphomas are uncommon, accounting for only 10% to 15% of all non-Hodgkin's lymphomas. The classification of these neoplasms has been controversial. In contrast to B-cell lymphomas, cytologic features have not been useful in defining disease entities, and cytologic grade has not helped predict the clinical course. Similarly, many entities of T-cell or natural killer (NK) cell derivation do not have a specific immunophenotype. Clinical features are of major importance in defining T-cell and NK cell neoplasms, and in some cases the clinical syndrome, may be more important than the precise cell of origin. The majority of cytotoxic T-cell and NK cell lymphomas arise in extranodal sites. The expression of cytotoxic molecules in these lymphomas may predispose to apoptosis by tumor cells and normal bystander cells. Three major categories of extranodal T/NK cell tumors are recognized in the World Health Organization (WHO) classification: extranodal NK/T, nasal-type; enteropathy-type; and subcutaneous panniculitis-like. Epstein Barr virus (EBV) is closely linked to nasal NK/T-cell lymphoma, but shows geographic and racial variations in other subtypes. Tumors resembling the prototype of nasal NK/T-cell lymphoma occur in a variety of extranodal sites, and are referred to as nasal-type. Hepatosplenic T-cell lymphoma is a more systemic disease derived from functionally immature cytotoxic cells, usually gammadelta T-cell origin. Cytotoxic T-cell lymphomas of mature gammadelta T-cell origin most often arise in mucocutaneous sites, and may resemble the prototypes of extranodal T/NK cell lymphoma: nasal, enteropathy-associated, and panniculitis-like. Cytotoxic T/NK cell lymphomas occur with increased frequency in the setting of immune suppression, especially following organ transplantation. The nodal T-cell lymphoma most often exhibiting a cytotoxic immunophenotype is anaplastic large cell lymphoma (ALCL). Primary cutaneous ALCL frequently but not invariably expresses cytotoxic molecules. While the majority of extranodal neoplasms are derived from innate immune effector cells of NK cell and T-cell origin (gammadelta greater than alphabeta), most nodal cytotoxic T-cell lymphomas probably belong to the adaptive immune system. Studies of these neoplasms may assist in unraveling the diversity of their normal counterparts.

Lymphomas of the oral cavity: histology, immunologic type, and incidence of Epstein-Barr virus infection

The purpose of this study was to determine the histologic class and immunologic phenotype of lymphomas presenting initially in the oral cavity and whether this correlated to a high incidence of Epstein-Barr virus (EBV) infection as has been reported with lymphomas in the nasal cavity. Seventy-one cases of oral lymphomas from the oral pathology referral service were analyzed retrospectively. They were classified according to the Revised European American Lymphoma (REAL) classification system using routine immunohistochemistry. EBV infection was determined by detection of early viral RNA sequences (EBER) and latent membrane protein (LMP-1) expression. Only non-Hodgkin's lymphomas were observed, with a female predominance of 2:1. They were primarily of B-cell origin and histologically classified mainly as large B-cell type (68%); T-cell lymphomas were rare (8%). EBV infection was observed in 14% of the B-cell lymphomas, an incidence rate higher than that reported in studies of B-cell lymphomas not located in the oral cavity but not as high as that observed in pleomorphic T-cell lymphomas (all sites, 36%) or nasal cavity T-cell lymphomas (nearly 100%). Interestingly, EBV proliferation did not correlate with expression of either Bcl-2 or p53.

Association of primary pleural effusion lymphoma of T-cell origin and human herpesvirus 8 in a human immunodeficiency virus-seronegative man

We describe a case of an 87-year-old human immunodeficiency virus (HIV)-negative man who developed a primary pleural lymphoma without any identifiable tumor mass associated with human herpesvirus 8 (HHV-8) infection. A large T-cell lymphoma was diagnosed based on morphologic, immunophenotypic, and molecular findings. The HHV-8 DNA sequences were detected using specific polymerase chain reaction amplification in the lymphomatous effusion. Study of the patient's serum confirmed the HHV-8 infection. This case report displays the characteristic features of HHV-8-related body cavity-based lymphoma/primary effusion lymphoma previously reported in HIV-seronegative patients, except that it is of T-cell origin. Whether this case may be included or not within the primary effusion lymphoma entity, the association of a pleural T-cell non-Hodgkin lymphoma with HHV-8 infection raises the question of the possible occurrence of T cells as the target of malignant transformation associated with HHV-8 infection.

Nonhepatosplenic gamma delta T-cell lymphoma with initial testicular compromise

We report here a case of nonhepatosplenic gammadelta T-cell lymphoma with undescribed initial localization in testis, without hepatosplenomegaly or adenopathies, and subsequent development in the maxillary sinus. The maxillar mass biopsy revealed a T-cell infiltration, and its immunologic characterization by flow cytometry showed a gammadelta T-cell phenotype (CD45+, CD3+, CD2+, TCR gammadelta+), without expression of CD7, CD5, CD1a, TdT, CD4, CD8, TCR alphabeta, or NK antigens (CD16, CD56, and CD57). Clonal gamma-chain gene rearrangement by polymerase chain reaction (PCR) was detected in testicular and maxillar biopsies. Epstein-Barr virus type 1 (EBV) sequences were detected by molecular biology in the biopsy material, suggesting that this oncogenic virus may play a role in the genesis of the clonal expansion of gammadelta T-cells. The patient was initially treated with standard chemotherapeutic protocols, with poor response and aggressive course.

Expression of cytotoxic proteins in peripheral T-cell and natural killer-cell (NK) lymphomas: association with extranodal site, NK or Tgammadelta phenotype, anaplastic morphology and CD30 expression

Most peripheral T-cell lymphomas (PTCL) express the alphabeta T-cell receptor (TCR) whereas rare PTCL express the gammadelta TCR. Most if not all gammadelta PTCL are extranodal lymphomas and among them, hepatosplenic gammadelta PTCL constitute a distinct clinicopathological entity. Besides alphabeta and gammadelta PTCL, there is a recently recognized group of extranodal, mainly nasal tumours, which display, in most instances, phenotypic and genotypic features of Natural-Killer cell non-Hodgkin's lymphomas (NK-NHL). Cytotoxic cells, including NK cells and cytotoxic alphabeta and gammadelta T lymphocytes may induce lysis of the target by using granule-associated cytotoxic proteins such as the T-cell intracellular antigen-1 (TIA-1), perforin and granzyme B. Expression of TIA-1 can be detected in all cytotoxic cells whereas granzyme B and perforin expression can be detected in high levels only in activated cytotoxic cells. Recently, several studies showed that the expression of these cytotoxic proteins in tumour cells of PTCL and NK-NHL is associated with a) extranodal site of clinicopathological presentation b) NK or Tgammadelta-cell phenotype c) CD30 expression in cutaneous T-cell lymphoproliferations and d) anaplastic morphology in nodal PTCL. This latter finding contrasts with the data that only rare Hodgkin lymphomas (HL) express cytotoxic proteins in Hodgkin and Reed-Sternberg cells. Altogether the data of the literature indicate that most extranodal T and NK-NHL are activated cytotoxic lymphomas with the notable exception of hepatosplenic gammadelta PTCL which represent tumours of non-activated cytotoxic cells. On this basis, it is suggested that the expression of cytotoxic proteins may be useful for the identification and classification of extranodal T and NK-cell lymphomas and, to some extent, for the differential diagnosis between HL and CD30+ anaplastic large cell lymphomas. Cytotoxic lymphomas are preferentially localized in extranodal sites such as skin, lung, upper respiratory and gastrointestinal tracts, which are continuously exposed to various antigens. Since cytotoxic T and NK cells are regarded as first line of defense in these sites, and some cytotoxic tumours such as nasal lymphomas and enteropathy-type intestinal lymphomas are associated with EBV and gliadin, respectively, it is likely that chronic antigen exposure may play a role in the pathogenesis of cytotoxic lymphomas occurring in mucosa and/or skin. Besides chronic antigenic stimulation, chronic immunosuppression may also have pathogenetic significance in cytotoxic lymphomas in view of their increased incidence in immunocompromised patients.

Primary intestinal non-Hodgkin's lymphoma and Epstein-Barr virus: high frequency of EBV-infection in T-cell lymphomas of Mexican origin

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.

Primary intestinal gamma-delta T-cell lymphoma with evidence of Epstein-Barr virus

AIMS

Primary intestinal T-cell lymphomas account for about 5% of all primary gastrointestinal lymphomas and are mostly associated with coeliac disease. They usually express the CD3-associated T-cell receptor alpha/beta heterodimer and HML1, and some are related with Epstein-Barr virus (EBV). As far as we know, the present report describes the first case of primary gamma-delta (gamma delta) EBV-associated intestinal T-cell lymphoma without enteropathy. Only hepatosplenic, nasal and cutaneous gamma delta T-cell lymphomas have previously been described.

METHODS AND RESULTS

Our case concerned a 43-year-old man with no history of coeliac disease, who presented with multifocal small bowel involvement showing high grade T-cell lymphoma with medium sized and large pleomorphic cells and a small pleomorphic T-cell component. Angioinvasion and angiocentricity were occasionally present. Immunohistochemical studies of lymphoma cells showed a T-cell gamma delta phenotype (CD3+, CD2+, TCR delta 1+, V delta 2+ and beta F1-) without expression of CD4, CD8, CD5, or HML1. Most tumour cells were positive for the cytotoxic granular proteins TiA1 and granzyme B. Rearrangement of the TCR gamma chain gene was demonstrated by polymerase chain reaction and in-situ hybridization with EBER probes revealed strong nuclear positivity in virtually all neoplastic cells.

CONCLUSION

We described the first case of primary intestinal gamma delta T-cell lymphoma without enteropathy in which EBV might fulfil a pathogenic role.

The Epstein-Barr virus in malignant non-Hodgkin's lymphoma of the upper aerodigestive tract

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.

Primary Non-Hodgkin's Lymphoma of the Intestine: High Prevalence of Epstein-Barr Virus in Mexican Lymphomas as Compared With European Cases

Recent studies in Western European populations have shown that peripheral T-cell non-Hodgkin's lymphomas (T-NHLs) are associated with Epstein-Barr virus (EBV) in a higher percentage than sporadic B-cell NHL (B-NHLs), and that the frequency of EBV-positivity might be influenced by the primary site of the tumor. Because of the geographic differences in EBV expression in Burkitt's lymphoma (BL) and Hodgkin's disease (HD), and the lack of studies of sporadic NHL from developing countries, we decided to survey the presence of EBV in a series of primary intestinal lymphomas from patients in Mexico and in Western Europe, and to analyze whether EBV status is influenced by tumor phenotype, and geographic or ethnic determinants. Paraffin-embedded tissue from 43 primary intestinal NHLs (19 cases from Mexico and 24 from Western Europe) were examined, including 17 high grade B-NHLs, 9 low grade B-NHLs, and 17 T-NHLs; 6 of which were enteropathy associated T-cell lymphomas. The distribution of histologic subtypes was similar in both groups. The presence of EBV was investigated with a combined approach using a nested polymerase chain reaction technique as well as immunohistochemistry for latent membrane protein-1 and in situ hybridization for EBV early RNA transcripts (EBER 1/2) RNAs. The median age of the Mexican patients was significantly lower than the median age of the European patients (32 v 62 years). This difference was most pronounced in patients with T-cell lymphoma (24 v 63 years). EBER-positive tumor cells were detected in 13 of the 43 (30%) cases of primary intestinal lymphoma, including 5 of 26 sporadic B-NHL (3 high grade and 2 low grade), and 8 of 17 T-NHL, all of which were classified as pleomorphic, medium and large cell. The rates of EBV-positivity were markedly different for European and Mexican cases. Whereas 7 of 7 (100%) T-NHL and 5 of 12 (42%) sporadic B-NHL of Mexican origin were EBER-positive, only 1 of 10 T-NHL and 0 of 14 sporadic B-NHL from Europe showed EBER expression in tumor cells. Latent membrane protein was positive in only 2 of 43 cases, 1 of which was an EBER-negative high grade B-NHL from Mexico that showed intact total mRNA in control hybridization. CD30 expression was found in 4 of 8 EBV-positive T-NHL and in none of the EBV-positive B-NHL. In contrast to European cases, intestinal NHLs from Mexico show a very high frequency of EBV-positivity, which is not limited to T-NHL, but includes a significant proportion of B-NHL. This study strongly suggests that similar to HD and probably BL, there are important epidemiologic differences in EBV association in intestinal T-cell NHL between European and Mexican populations. These differences might be the result of environmental factors, for example, earlier contact with childhood viruses on intestinal lymphomagenesis.

Nasopharyngeal lymphomas: further evidence for a natural killer cell origin

The authors report four cases of sinonasal lymphomas with immunophenotypic (four cases) and genotypic (three cases) studies. These lymphomas are frequent in Oriental countries, but unusual in Western populations, particularly in France. Although they have been originally considered as T-cell lymphomas, their origin remains unclear, and several authors have recently suggested that they are a natural killer (NK)-cell proliferation. The tumor cells of the four cases reported here showed characteristics of NK cells. On cryostat sections, they were CD3 negative, but CD2 and CD56 positive. The cytoplasm of the tumor cells exhibited azurophilic granulations. Using polymerase chain reaction (PCR), no clonal rearrangement of the T-cell receptor gamma gene was present. Furthermore, clinically, two presented a pharyngeal involvement, and two were also characterized by hepatosplenic involvement at the time of the diagnosis. Thus, the present cases provide additional evidence toward the NK-cell origin of these rare lymphomas. Many sinonasal lymphomas, including the present cases, are positive for Epstein-Barr virus (EBV) (LMP-1 antibody and EBER-messenger RNA probes). This may suggest an important role of EBV as a local factor in their pathogenesis.