Study of Epstein-Barr virus early RNA 1 (EBER1) expression by in situ hybridization in thymic epithelial tumors of Chinese patients in Taiwan

Thymic Lymphoepithelial Carcinoma Associated with Epstein-Barr Virus: Experiences and Literature Review

Thymic lymphoepithelial carcinoma (TLEC) is a primary thymic carcinoma that accounts for about 14% of all thymic epithelial tumors and is classified into 14 types. The histological morphology is similar to lymphoepithelioma, a type of undifferentiated nasopharyngeal carcinoma. It has been reported that squamous carcinoma accounts for approximately 80% of thymic carcinoma, followed by TLEC, which accounts for 6%. TLEC has been reported to be associated with Epstein-Barr virus (EBV), with EBV infection in TLEC tumor cells first noted by Lyvraz et al. in 1985. Tumors shown to be EBV-positive are classified as TLEC if lymphoplasmacytic infiltration is lacking. However, only about 50% of the cases are positive for EBV, which is lower compared to nasopharyngeal lymphoepithelioma. Instances of EBV infection in other types of thymic epithelial tumor have been reported at lower rates, which suggests that EBV infection may have an important influence on the carcinogenesis of TLEC, though the etiology is unknown. TLEC is a highly malignant tumor with poor prognosis, as affected patients have a median survival time of 22 months, according to 58 cases from the literature, while the 5-year survival rate is 34.4%. Presently, prognosis is not considered to be affected by the presence or absence of EBV positivity.

Viral infection in thymoma and thymic tumors with autoimmune diseases

A thymoma is a type of thymic tumor which is rarely malignant that is frequently reported in adult patients. A number of thymoma-related immune disorders are observed including autoimmune diseases, which suggests a strong connection between thymoma development and immunological mechanisms. Characterized by association with humoral and cellular immunodeficiency, thymoma patients are susceptible to opportunistic infections by environmental factors. Recent reports have suggested that viral infection may play a role in the etiological mechanisms of thymoma development associated with dysregulated immunity. In this review, we summarize the case reports and studies related to viral infection, such as CMV, EBV and HSV, that probably play a part in the pathogenesis of thymoma and related diseases. Furthermore, we demonstrate the underlying mechanisms by which viruses may induce the occurrence of thymoma with autoimmune diseases. Lastly, we discuss the potential application of antiviral therapy in the treatment of thymic diseases.

Extended thymectomy with blood vessel resection and reconstruction improves therapeutic outcome for clinical stage III thymic carcinoma patients: a real-world research

OBJECTIVES

We examine the therapeutic efficacy of extended thymectomy with blood vessel resection and reconstruction in thymic carcinoma patients with great vessel invasion.

METHODS

In total 26 patients diagnosed as clinical stage III thymic carcinoma with severe great vessel invasion were enrolled in this retrospective study. Among these patients, 14 cases received adjuvant chemo- and radiotherapy (non-operation subgroup, NOG), the other 12 patients received extended thymectomy with vessel resection and reconstruction followed by the adjuvant treatment (operation subgroup, OG).

RESULTS

All surgical procedures went smoothly with no perioperative death. R0 resection was obtained in all surgical cases, and we also observed a lymph node metastasis rate of 38.8%. The overall survival (OS) was 34 months for the whole cohort, 48 and 26 months for the OG and NOG respectively (p = 0.013). The median disease metastasis free survival (DMFS) was 47 months for the OG and 18 months for the NOG (p = 0.019).

CONCLUSION

Extended thymectomy with vessel resection is feasible for patients with clinical stage III thymic carcinoma. Surgery significantly improves the overall survival and the prognosis of clinical stage III thymic carcinoma.

Epstein-Barr Virus-Associated Pulmonary Carcinoma: Proposing an Alternative Term and Expanding the Histologic Spectrum of Lymphoepithelioma-like Carcinoma of the Lung

Lymphoepithelioma-like carcinoma (LELC) of the lung is a rare Epstein-Barr virus (EBV)-associated carcinoma. It is histologically characterized by a syncytial growth pattern with marked lymphocytic infiltration that is indistinguishable from the histology observed in undifferentiated nasopharyngeal carcinomas. However, it has been noted that LELC can display nonclassic morphology and lack significant lymphocytic infiltration. In this study, we conducted a comprehensive clinicopathologic analysis of 61 patients with pulmonary LELC and performed automatic quantification of the lymphocytic infiltrate using the IHC Profiler software. We demonstrated that pulmonary LELCs have a morphologically continuous spectrum, ranging from classic poorly differentiated tumors with intense lymphocytic infiltration to nonclassic morphology with little lymphocytic infiltration. These EBV-associated tumors represent a distinct entity and usually occur in female and nonsmoking patients. Tumors with low lymphocytic infiltration can closely resemble nonkeratinizing squamous cell carcinoma and tend to be larger in size, have higher maximum standardized uptake values on radiography, and exhibit shorter times to recurrence than those with high lymphocytic infiltration. Through detailed pathologic examination, we observed several distinct morphologic features in pulmonary LELCs, including granulomatous inflammation, focal keratinization, spread through alveolar spaces, and lepidic spreading pattern. We also found that patients with tumors exhibiting granulomatous inflammation have favorable outcomes; however, spread through alveolar spaces did not significantly correlate with prognosis. As many of these "LELCs" do not resemble undifferentiated nasopharyngeal carcinoma or lymphoepithelioma, we propose using an alternative term, EBV-associated pulmonary carcinoma, to encompass the entire morphologic spectrum of this distinct disease entity.

Association between Epstein-Barr virus and Thymic epithelial tumors: a systematic review

The possible role of Epstein-Barr virus (EBV) in the pathogenesis of thymic epithelial tumors (TET) remains controversial. This study aimed to determine the prevalence of EBV in TET. We conducted a systematic review of relevant English-language studies published between January 1980 and December 2013. Effect size was calculated as event rates (95% confidence interval [CI]) by homogeneity testing using Cochran’s Q and I² statistics for benign TET, benign TET with myasthenia gravis (MG), and thymic carcinoma (TC). Among 136 potentially relevant studies, 22 met the inclusion criteria. Despite a considerable degree of heterogeneity, the pooled estimated incidences were 9% (95% CI, 1–23%), 20% (95% CI, 0–54%), and 6% (95% CI, 0–21%) for benign TET, benign TET with MG, and TC, respectively. There was significant heterogeneity among studies that used in situ hybridization (ISH) for both benign TET and benign TET with MG. According to the random-effects model, studies employing ISH yielded lower point estimates of EBV prevalence (5%) than those employing other methods (33%). Using the random-effects model, we found a lack of significant heterogeneity among studies from different geographic regions (p = 0.0848). Further, 12 of 23 lymphoepithelioma-like carcinoma (LELC) cases tested EBV-positive. The prevalence of EBV in benign TET with or without MG was lower than in nasopharyngeal carcinoma, suggesting that EBV plays a minor role in TET pathogenesis. Although the prevalence of EBV in TC was also low, EBV may play an important causal role in LELC. Further research is needed to clarify these associations.

Ultrasonographic findings of intrahepatic lymphoepithelioma-like cholangiocarcinoma associated with Epstein-Barr virus: Two cases report

RATIONALE

Epstein-Barr virus (EBV)-related lymphoepithelioma-like cholangiocarcinoma (LELCC) is an extremely rare primary liver tumor with nonspecific clinical manifestations. The clinicopathological features of EBV-associated LELCC have been reported in a few cases. But reports of the tumor's imaging characteristics, particularly ultrasonographic findings, are very rare.

PATIENT CONCERNS

The first patient was a 64-year-old man with left upper quadrant pain and no nausea and dizziness for about 3 months. The second patient was a 40-year-old man, had an incidental finding of a hepatic tumor in a routine health checkup at a local hospital.

DIAGNOSES

In the first patient, the abdominal ultrasound demonstrated a slightly heterogeneous hypoechoic nodule in segment 3 of the liver. The nodule was about 2.0 cm × 1.7 cm in size, with a clear margin and regular shape. Color Doppler flow imaging (CDFI) revealed no blood flow signals in this nodule. According to the clinical information and imaging features, it was difficult to determine the diagnosis of the nodule. In the second patient, gray-scale ultrasound revealed a slightly heterogeneous hypoechoic mass measuring 3.5 cm × 2.5 cm with well-defined margin and regular shape at the superior segment of the left hepatic lateral lobe. There was a blurrily hypoechoic halo around the mass. In contrast-enhanced ultrasound (CEUS), the mass was homogeneous hyperenhancement in the arterial phase. In the portal phase and late phase, the center enhancement of the mass washed out gradually, presenting hypoenhancement, Therefore, the tumor was diagnosed as malignancy.

INTERVENTION

Finally, a laparoscopic left hepatic lateral lobectomy was performed in the first patient. The second patient underwent a left hepatectomy with cholecystectomy.

OUTCOMES

The first patient has been alive without recurrence or distant metastases for 11 months since the surgery. The second patient received routine follow-up after surgery. Until now, he has been tumor-free for 32 months.

LESSONS

We mainly focus on the ultrasound characteristics of EBV-associated LELCC, especially its enhancement patterns on CEUS, which may provide valuable information for diagnosis of the LELCC. When a liver tumor with typical CEUS patterns of malignancy is found in middle-aged adults with EBV positive, the possibility of EBV-related LELCC should be considered.

Presence of lytic Epstein-Barr virus infection in nasopharyngeal carcinoma

BACKGROUND

Chromogenic Epstein-Barr virus-encoded RNA (EBER) in situ hybridization (EBER-ISH) is the gold standard to detect Epstein-Barr virus (EBV) but it is difficult to use in conjunction with immunohistochemistry (IHC). In this study, our purpose was to validate the sensitivity and specificity of RNAscope in detection of EBV infection in nasal epithelium and its stroma.

METHODS

Fluorescence-based RNAscope EBER-ISH, BRLF1-ISH, and lineage marker-IHC were performed on archived formalin-fixed paraffin-embedded tissues from normal nasal cavity (n = 5), nasopharynx (n = 8), and nasopharyngeal carcinoma (NPC) specimens (n = 10).

RESULTS

The EBERs were detected in 10 of 10 NPC samples but was absent in all normal tissues from the nasal cavity and nasopharynx. The EBERs were exclusively located in pan-cytokeratin (pan-CK)-positive tumor epithelial cells but not in CD45-positive leukocytes and vimentin-positive stromal fibroblasts. The level of EBER expression varied in tumor cells within patient and between patients as well. Additionally, 5 of 10 patients had positive BRLF-ISH.

CONCLUSION

We developed a simple and reproducible method to simultaneously detect mRNA and protein in formalin-fixed paraffin-embedded tissues of NPC. As a single staining, traditional EBER continues to be useful; however, for interpretation of the phenotype of EBV-infected cells, RNAscope is superior. Significantly, we showed that lytic EBV infection took place in NPC tumors.

A rare highly aggressive tumour: lymphoepithelioma-like thymic carcinoma

Lymphoepithelioma-likethymic carcinoma is a rare neoplasm that presents with compressive symptoms or as an incidental radiological finding of an anterior mediastinal mass. It is an aggressive carcinoma with a high rate of invasion, metastasis and recurrence. Its diagnosis usually carries a poor prognosis largely due to propensity for late diagnosis. To date, guidance for treatment remains limited. This is a case of lymphoepithelioma-like thymic carcinoma in a young male adult who presented initially with back pain. Despite prompt initiation of chemotherapy with cisplatin, doxorubicin and cyclophosphamide, he had a complicated hospital course leading to demise within 2 months of diagnosis.

Lack of Evidence of Pathogenetic Role of Epstein-Barr Virus in Thymic Lymphoid Hyperplasia and Thymomas in the Chinese Population of Hong Kong

A previous study from Hong Kong by McGuire et al. reported frequent demonstration of Epstein-Barr virus (EBV) DNA by Southern blot analysis in thymoma, thymic lymphoepithelioma-like carcinoma, and thymic lymphoid hyperplasia. This provoca tive finding, however, could not be confirmed by studies in the Western populations using the Southern blot technique and/or polymerase chain reaction to detect EBV- DNA or in situ hybridization to detect EBV encoded RNA (EBER), raising the possibility that the association with EBV may be restricted to Asians. This study was performed to clarify this issue by using a highly sensitive localization technique for EBER on a larger series from the Asian population of Hong Kong. Paraffin sections obtained from 10 cases of thymic lymphoid hyperplasia, 42 noninvasive thymomas (including one case previously reported to be EBV positive), 11 invasive thymomas, and 9 thymic carcinomas (including 5 cases of lymphoepithelioma-like carcinoma) were studied. EBER signal was not detected in the epithelial cells in any of the cases except for two cases of lymphoepithelioma-like carcinoma. In two thymomas, a few small lympho cytes (<0.1%) were EBER positive. Failure to detect EBER was not an artifact due to RNA denaturation, because preserved mRNA could be demonstrated by oligo-dT labelling in 56 of the 72 cases. Thus, the results of this study on Hong Kong Chinese are in keeping with those reported in Caucasians, and more recently in Japanese and Taiwan Chinese, in that there is no association of EBV with thymic lymphoid hyperpla sia or thymoma, and that EBV may be demonstrated in a proportion of thymic lymph oepithelioma-like carcinomas. The positive results previously reported cannot be ex plained, because the occasional EBV-carrying lymphocytes detected in rare cases of thymoma should be insufficient to give a positive EBV result by Southern blot tech nique. Int J Surg Pathol 2(1):17-22, 1994

Malignant Lymphoepithelial Lesions of the Salivary Gland

OBJECTIVES: To describe a relatively large series of patients with uncommon malignant lymphoepithelial lesions (MLEL) in the salivary glands, to present treatment-outcome data to support therapeutic decision-making, and to evaluate the incidence of cooccurrence of MLEL and Epstein-Barr virus (EBV).

STUDY DESIGN AND SETTING: Ten patients with MLEL were treated between 1987 and 2002. All lesions were surgically removed, with or without neck dissection, and the patients treated with radiotherapy or radiotherapy and chemotherapy. Histopathology and in situ hybridization studies for EBV-encoded RNA (EBER1) were performed.

RESULTS: With aggressive treatment, outcomes were good, regardless of the presenting stage, except when distal metastases were present. All 10 patients tested positive for EBV.

CONCLUSION AND SIGNIFICANCE: This and previous investigations support the use of aggressive surgical excision of the tumor and local metastases and radiotherapy or radiotherapy and chemotherapy, as optimal treatment for MLEL. The EBV finding may indicate a role for EBV in the pathogenesis of MLEL.

Clinical outcome of thymic lymphoepithelioma-like carcinoma: Case report of a 14-year-old male

Thymic carcinoma is a rare type of cancer, which arises from the thymic epithelium and accounts for ~1–4% of anterior mediastinal tumors in the USA. It rarely occurs in children, and is rarer among adults. Thymic lymphoepithelioma-like carcinoma (LELC) is an uncommon subtype of thymic carcinoma in children, however, it is one of the common histological subtypes of thymic carcinoma in adults. In the present study, a 14-year-old male patient presented to the Tokyo Metropolitan Cancer and Infectious diseases Center, Komagome Hospital (Tokoyo, Japan) with chest pain due to a large anterior mediastinal mass. The patient was histologically diagnosed with thymic LELC via a needle biopsy specimen, which was obtained from the primary site and indicated the Epstein-Barr virus infection, whose markers are also associated with oncogenesis. Immunohistochemical analysis demonstrated positive staining for keratin (AE1/AE3), epithelial membrane antigen, and latent membrane protein-1 and negative staining for cluster of differentiation 5. Thus, the patient was diagnosed with metastatic thymic LELC. First-line chemotherapy comprising of a cisplatin- and adriamycin-based chemotherapy regimen achieved a partial response, however, the patient succumbed within 10 months of the initial diagnosis due to rapid disease progression and refractory to subsequent cycles of chemotherapy. Thus, the current study, as well as previously reported cases, demonstrates that pediatric patients with thymic LELC continue to have a poor prognosis.

Lymphoepithelioma-like carcinoma of the vulva: a case report

This report describes a lymphoepithelioma-like carcinoma of the vulva in a 64-year-old woman. The tumor showed distinct morphologic features including syncytial sheets of malignant epithelioid cells and a dense lymphoplasmacytoid infiltrate. In situ hybridization and immunohistochemistry for Epstein-Barr virus were negative. The tumor was treated by surgical excision. No evidence of recurrence has been detected 3 years after treatment. To our knowledge this is the second reported case of lymphoepithelioma-like carcinoma of the vulva.

Epidemiology of thymoma and associated malignancies

BACKGROUND

Thymoma is a rare malignancy of unknown etiology.

METHODS

The author examined patterns in thymoma incidence in the US general population using data from Surveillance, Epidemiology, and End Results (SEER) cancer registries. Prior studies concerning the risk of additional malignancies in thymoma patients were reviewed.

RESULTS

Based on cancer registry data, the overall incidence of thymoma in the US is 0.13 per 100,000 person-years. Thymoma is exceedingly uncommon in children and young adults, rises in incidence in middle age, and peaks in the seventh decade of life. Thymoma incidence is especially high among Asians and Pacific Islanders in the US. While several studies based at single treatment centers have suggested that thymoma patients have a broadly increased risk for other malignancies, follow up data from US cancer registries support a more limited spectrum of cancer risk. In particular, thymoma patients have a subsequently elevated risk for developing B-cell non-Hodgkin's lymphoma. Based on limited data, thymoma patients may also have an elevated risk for developing soft tissue sarcomas.

DISCUSSION

Thymoma is a rare malignancy. The excess risk for non-Hodgkin's lymphoma is consistent with an effect of immune disturbance arising from the thymoma or its treatment. While descriptive epidemiologic data may yield clues to the etiology of thymoma, large multi-center case-control studies will be required to formally evaluate environmental and genetic risk factors.

Epstein-Barr virus (EBV) associated lymphoepithelioma-like thymic carcinoma associated with paraneoplastic syndrome of polymyositis: a rare tumor with rare association

Thymic carcinomas are rare neoplasms representing less than 1% of all thymic malignancies arising from thymic epithelium. Lymphoepithelioma-like thymic carcinoma is a high grade neoplasm with aggressive features and frequent metastasis. Association of lymphoepithelioma-like thymic carcinomas with Epstein-Barr virus was observed in several previously reported case reports. Paraneoplastic syndromes have been reported with lymphoepithelioma-like thymic carcinoma. We report a case of rare association of paraneoplastic syndrome of polymyositis with lymphoepithelioma-like thymic carcinoma. The case highlights generalized increase in fluoro-deoxy-glucose uptake in the skeletal muscles indicating biopsy proven polymyositis-a paraneoplastic syndrome.

Thymic lymphoepitheliomalike carcinoma in children: clinicopathologic features and molecular analysis

Thymic lymphoepitheliomalike carcinoma (LELC) in children is extremely rare and we report 2 such cases with molecular analysis of Epstein-Barr virus (EBV) and its encoded latent membrane protein-1 as well as a literature review. Both of our patients were male, presented with a huge anterior mediastinal mass, expired within a year after diagnosis despite treatment. There were altogether 9 cases of thymic LELC in children. Their common clinical features include a male predominance, large tumor size, advanced clinical stage, and poor clinical outcome. All cases were associated with EBV and nearly half developed concurrent hypertrophic osteoarthropathy (HOA). Thymic LELC in children is an aggressive EBV-associated malignant tumor frequently accompanied by HOA. We proposed that EBV might play a role in the development of HOA through the interactions of latent membrane protein-1, vascular endothelial growth factor, and cyclooxygenases-2.

Epstein-Barr virus in patients with chronic lymphocytic leukemia: a pilot study

The objective of this study was to assess the incidence and the clinical significance of Epstein-Barr virus (EBV) in patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Patients with CLL/SLL who presented at The University of Texas M. D. Anderson Cancer Center over a 2-year period and had available marrow paraffin blocks were studied for evidence of EBV infection using a highly specific in-situ hybridization assay for detection of EBV encoded RNA (EBERs). Results were analysed in relation to other presenting characteristics and outcome. Thirty-two patients were examined. EBERs were detected in the bone marrow of 12 of 32 (38%) CLL/SLL marrows vs 0 of 20 normal marrows (p = 0.002). EBERs were observed in sporadic granulocytes alone or in addition to its presence in lymphocytes in nine of the 12 EBV-positive patients. EBERs were detected less frequently in patients with Rai stage 0 - 1 disease (20%) compared with Rai stage 2 - 4 (66%; p = 0.008). EBER-positive patients tended to have higher lactate dehydrogenase levels (p = 0.053). The 10-year survival rate was 22% vs 58% for patients with and without discernible EBERs (log-rank, p = 0.08). Evidence of EBV infection was found in 38% of patients with CLL/SLL. Despite the small number of patients tested, discernable EBERs were significantly more common in individuals with more advanced Rai stage and there was a trend toward shorter survival in patients in whom EBV EBERs were discerned. Larger studies are needed to determine the prognostic value and role of EBV infection in patients with CLL/SLL.

Thymic carcinoma: update of current diagnostic criteria and histologic types

Thymic carcinomas are rare tumors thought to derive from thymic epithelium. Because of the complex embryological origin of the thymus, whose development includes contributions from the third and, to a lesser extent, the fourth pharyngeal pouches, thymic carcinomas are endowed with great morphologic heterogeneity. A large number of histologic types have been described that resemble tumors arising in other organs. Unfortunately, no definitive pathognomonic histological features or immunohistochemical markers are associated with these tumors, making them a real challenge for diagnosis. Because of their close similarity with tumors arising at other organs, the diagnosis of thymic carcinoma must be regarded, for the most part, as a diagnosis of exclusion. This review will focus on current criteria for diagnosis of these tumors, with a review of the various histopathologic appearances that they can adopt.

Lymphoepithelioma-like carcinoma of the breast. Report of a case with the first electron microscopic study and review of the literature

Lymphoepithelioma-like carcinoma (LELC) is a tumor which occurs outside the nasopharynx and has morphological features identical to nasopharyngeal lymphoepithelioma. LELC of the breast (LELC-B) is uncommon, and its resemblance to medullary carcinoma of the breast (MC-B) obscures distinction between these two tumors. We report a case of LELC-B occurring in a 47-year-old woman. The tumor consisted of multinodules without circumscription. The tumor cells mainly exhibited loose clusters being permeated by numerous lymphocytes. The tumor cell clusters showed inconspicuous margins, which were far from syncytial patterns. The epithelial nature of the tumor cells was demonstrated by positivity for epithelial membrane antigen, AE1/AE3 and CAM5.2. Furthermore, glandular differentiation of the tumor cells was confirmed using electron microscopy for the first time. Epstein-Barr virus (EBV) was not detected using either in situ hybridization or polymerase chain reaction. These findings, together with former reports of LELC-B, suggest that the distinction between LELC-B and MC-B depends on whether circumscription and syncytial growth patterns exist. The other findings, including absence of EBV and immunohistochemical aspects of the tumor cells, are not considered different thus far. Although the prognosis of LELC-B is thought to be favorable, which is also similar to MC-B, distant metastasis was detected in the present case. To confirm the clinicopathological entity of these two tumors, it is important to recognize the difference between LELC-B and MC-B.

Thymic carcinoma: a clinicopathological and immunohistological study of 19 cases

AIMS

To study 19 cases of primary thymic carcinoma in order to define the clinicopathological features and the precise histochemical profile of this rare and heterogeneous group of tumours of the anterior mediastinum.

METHODS AND RESULTS

The study group consisted of 13 males and six females, with a mean age of 58.5 years (range 29-75 years). Superior vena cava syndrome and chest pain were the main presenting symptoms. Three patients were asymptomatic. No patient had myasthenia gravis. Six different histological types were identified: neuroendocrine tumours (six patients), epidermoid carcinoma (five patients), sarcomatoid carcinoma (three patients), lymphoepithelioma-like carcinoma (two patients), mucoepidermoid carcinoma, clear cell carcinoma, and undifferentiated carcinoma (one patient each). The clear cell carcinoma was associated with a thymic cyst. No association with thymoma was observed. Surgical resection, performed in 10 cases, was complete in two. Sixteen patients received thoracic radiation, and 11 received systemic chemotherapy. Follow-up information was available in 16 cases; 12 patients presented with local or metastatic relapse, and 10 patients died of their tumour. The overall 5-year survival was 14.5%.

CONCLUSION

Primary thymic carcinoma is a very heterogeneous group of tumours of the anterior mediastinum with an aggressive clinical behaviour, and a poor overall prognosis.

Thymic carcinoma: state of the art review

Thymic carcinoma is a rare neoplasm with distinct clinical and pathological characteristics. The prognosis is often poor with an aggressive course that belies its numerical rarity. Potentially prognostic factors for survival include histopathologic grade, clinical stage, and resectability of the tumor. Five-year survival rates for all patients are approximately 30-50%, with a significant survival time differential between low-grade and high-grade neoplasms. Owing to the paucity of cases, optimal management of thymic carcinoma has yet to be defined. At present, a multimodality approach involving aggressive surgical resection, platinum-based combination chemotherapeutic interventions, and radiotherapy represent the preferred therapeutic approach. Though our knowledge remains somewhat speculative at present, several scientific, technological and therapeutic innovations may have a potentially significant impact on the future of this disease.

The EBV action in tonsils and adenoids

The bacteria involved in tonsil disease have been well studied, but we cannot say the same for the viruses. The method to detect virus make this approach difficult to study. Epstein–Barr Virus (EBV) infection usually occurs in early childhood and can persist in palatine and pharyngeal tonsil lymphocytes. EBV has been closely associated with the undifferentiated form of nasopharyngeal carcinoma (NPC) in its effect. Nevertheless, the presence of EBV in non-neoplastic lymphoid tissue of the nasopharynx and tonsil has rarely been investigated. Our objective was to study the frequency of EBV in tonsils and adenoids and to define the correlation between EBV and adenoid hyperplasia.

In this study, we looked for EBV in adenoid and tonsil tissue of 165 patients (2 and 15 years old ) by in situ hybridization (ISH) for EBER 1/2 RNA. Resection of the adenoids was done for relief of upper respiratory tract obstruction, and the tonsils were resected because of recurrent tonsillitis and/or hyperplasia with upper airway obstruction. We divided the adenoid samples in two groups: one group 12–24 months old (average 18 months old) and the second group, 25 months to 15 years old. Tonsils were obtained from 85 patients, 3–13 years old (mean age 5.6 years) who underwent surgery due to recurrent tonsillitis or hyperplasia.

EBV was demonstrated in lymphoid cells of 11 (34.3%) out of 32 adenoids for the first group and 36 (72%) out of 48 children of the second group. EBV was found in the respiratory epithelial cells of adenoid in one case.

Children under 24 months of age can be infected by EBV, and this virus might be responsible for obstructive hyperplasia. Tonsils are less affected by EBV than the adenoids, suggesting that the EBV is more attracted to the adenoid tissue than the tonsillar tissue.

Epstein-Barr virus-associated carcinomas: facts and fiction

The Epstein-Barr virus (EBV) is associated with several human tumours including lymphoid and epithelial malignancies. Most EBV-associated tumours are rare or occur at higher incidence only in certain geographical regions. The recently reported detection of EBV in gastric, breast, and hepatocellular carcinomas raises the possibility of involvement of the virus in the pathogenesis of common cancers. This article reviews the evidence linking EBV infection to epithelial tumours. It is concluded that at present, there is no convincing evidence to suggest that breast carcinoma and hepatocellular carcinoma are EBV-associated tumours.

Detection of Epstein-Barr virus genome within thymic epithelial tumours in Taiwanese patients by nested PCR, PCR in situ hybridization, and RNA in situ hybridization

Epstein-Barr virus (EBV) is known to be associated with a variety of tumours, including Burkitt's lymphoma, nasopharyngeal carcinoma, and some carcinomas of other organs with similar lymphoepithelioma-like features. The association between EBV and thymic epithelial tumours is inconclusive, as reports in this regard are not entirely consistent and the methods employed are of different sensitivity and specificity. This study examined 78 thymomas and 21 thymic carcinomas in Taiwanese patients, to detect the viral genome at both DNA and RNA levels. The tissue blocks were first screened by nested polymerase chain reaction (PCR) targeting on the first tandem internal repeats. The positive cases were further submitted for viral localization by in situ PCR insitu hybridization (ISH) and Epstein-Barr-encoded RNA-1 (EBER-1) ISH. None of the thymomas showed a detectable EBV genome. Eight thymic carcinomas were positive for EBV by nested PCR, of which six displayed nuclear signals within the tumour cells by in situ PCR ISH and/or RNA ISH, one displayed signals within the lymphocytes, and one showed no discernible in situ signals. Most of them exhibited a lymphoepithelioma-like morphology. These results show that nested PCR is a sensitive method for screening the EBV genome in thymic epithelial tumours. In situ PCR ISH is reliable for localization of the virus, in addition to EBER-1 RNA ISH. Thymomas are not related to EBV, even in this endemic area. Thymic carcinomas, especially the lymphoepithelioma-like thymic carcinomas, are more often associated with the virus.

In vivo effects of the Epstein-Barr virus small RNA EBER-1 on protein synthesis and cell growth regulation

Recent studies have suggested a role for the Epstein-Barr virus-encoded RNA EBER-1 in malignant transformation. EBER-1 inhibits the activity of the protein kinase PKR, an inhibitor of protein synthesis with tumour suppressor properties. In human 293 cells and murine embryonic fibroblasts, transient expression of EBER-1 promoted total protein synthesis and enhanced the expression of cotransfected reporter genes. However reporter gene expression was stimulated equally well in cells from control and PKR knockout mice. NIH 3T3 cells stably expressing EBER-1 exhibited a greatly increased frequency of colony formation in soft agar, and protein synthesis in these cells was relatively resistant to inhibition by the calcium ionophore A23187. Nevertheless clones containing a high concentration of EBER-1 were not invariably tumourigenic. We conclude that EBER-1 can enhance protein synthesis by a PKR-independent mechanism and that, although this RNA may contribute to the oncogenic potential of Epstein-Barr virus, its expression is not always sufficient for malignant transformation.

Relationship between Epstein-Barr virus and lymphoepithelioma-like carcinoma of the lung: a clinicopathologic study of 6 cases and review of the literature

Lymphoepithelioma-like carcinoma (LELC) is a rare form of lung cancer, usually encountered in Chinese patients. Similar to nasopharyngeal carcinoma, LELC of the lung is strongly associated with Epstein-Barr virus (EBV) infection in Asian patients, but there is controversy over whether an association exists in patients from Western countries. To determine whether such a relationship exists, we retrospectively studied 6 cases of primary LELC of the lung, all of which were in Western patients. There were 4 men and 2 women, ranging in age from 49 to 75 years. The tumors ranged from 1 to 4.5 cm in diameter. Four patients had stage I disease, 1 had stage IIb disease, and 1 had stage IIIa disease. All patients are alive without evidence of disease with a follow-up of 18 to 30 months. Formalin-fixed, paraffin-embedded tissue was stained with hematoxylin-eosin for routine evaluation and immunostained for keratin and leukocyte common antigen (LCA). LCA staining was performed to exclude large-cell lymphoma. Immunoperoxidase staining (1:500 clone CS1-4; Dako, Carpinteria, CA) and in situ hybridization were performed to detect EBV. Tumors consisted of solid nests of undifferentiated tumor cells in a syncytial arrangement surrounded by heavy lymphoplasmacytic infiltrate. Tumor cells stained positively for keratin but negative for LCA. All 6 cases were negative for EBV, suggesting no association between EBV and LELC in the Western population.

Intrahepatic cholangiocarcinoma with lymphoepithelioma-like component

We present two cases of intrahepatic cholangiocarcinoma with lymphoepithelioma-like component. The patients included one woman and one man, aged 67 and 41 years, respectively. They presented with right upper quadrant pain and epigastralgia. Histologically, both tumors showed two distinct histological patterns with dense lymphoplasma cell infiltration. The first pattern was a well to moderately differentiated adenocarcinoma; the second component showed a feature similar to lymphoepithelioma-like carcinoma. Granulomatous reaction was noted in one case. Immunohistochemical study revealed that both tumors were immunoreactive with AE1/AE3, cytokeratin 7, and cytokeratin 19 but negative for carcinoembryonic antigen and cytokeratin 20. The stromal lymphocytes were composed of predominantly CD3(+) T cells. In situ hybridization for Epstein-Barr virus (EBV)-encoded RNA (EBER) showed positive nuclear signal in tumor cells but not in inflammatory cells in one case. The presence or absence of EBV genome was confirmed by polymerase chain reaction of LMP-1 gene in both cases. The LMP-1 gene also had a 30-bp deletion in Exon 3 as compared with the products from B95-8 cells. We further sequenced the PCR product and confirmed a 30-bp deletion between Nucleotide (nt) 168,282 and nt 168,253 corresponding to the B95-8 sequence. The clinical significance of 30-bp deletion in Exon 3 of the LMP-1 gene in lymphoepithelioma-like carcinoma of the liver warrants further investigation.

Lymphoepithelioma-like carcinoma of the lung with a better prognosis. A clinicopathologic study of 32 cases

The purpose of our study was to clarify the prognosis of lymphoepithelioma-like carcinoma (LELC) of the lung, which is rare. We analyzed the clinicopathologic features of 32 cases of pulmonary LELC and compared the cases with 84 cases of pulmonary non-LELC with available long-term follow-up information. The results show that LELC of the lung as a distinct entity has a better prognosis than non-LELC. We found a significant difference in the survival rates between patients with LELC and patients with non-LELC in stage II and stages III and IV, respectively. Tumor recurrence and necrosis (5% or more of tumor) are associated with a poor prognosis. It seems that the histologic typing (Regaud type and Schmincke type) of pulmonary LELC is of no clinical value.

The spectrum of micronodular thymic epithelial tumours with lymphoid B-cell hyperplasia

AIMS

A rare type of thymoma, micronodular thymoma with lymphoid B-cell hyperplasia, was recently reported by Suster and Moran. Thymic epithelial tumours with a similar pattern but with varied cytological features of the tumour cells are analysed.

METHODS AND RESULTS

A total of 11 cases of thymic epithelial tumours characterized by micronodular proliferation of tumour cells separated by abundant lymphoid stroma with prominent germinal centres were reviewed clinicopathologically and examined immunohistochemically. The presence of Epstein-Barr virus (EBV) genome was also examined by in-situ hybridization. Based on the morphology of tumour epithelial cells, cases were subdivided into four groups: group 1 (two cases) having spindle epithelial cells; group 2 (two cases) showing an admixture of spindle and polygonal epithelial cells; group 3 (five cases) having polygonal epithelial cells, with mild to moderate cytological atypia in four cases, and group 4 (two cases) representing lymphoepithelioma-like carcinoma. The degree of cytological atypia and the number of tumour cells positive for MIB-1 and p53 gradually increased towards group 4. The abundant lymphoid stroma in all cases contained many CD20-positive B-cells and CD3 and CD45RO-positive T-cells. CD99-positive immature T-cells were present in all cases of groups 1 and 2 and in most cases of group 3, but not in both cases of group 4 tumours. IgG, IgM and IgD-positive plasma cells and lymphocytes were also present in all cases, more prominent in those of groups 3 and 4. The EBV genome was detected in only a few lymphocytes in five cases.

CONCLUSIONS

The tumours in this series belong to a distinct category of thymic epithelial tumours and each of the above groups may constitute a spectrum in the continuum of cytological atypia. The aetiological relationship of EBV with these tumours could not be proved. The lymphoid B-cell hyperplasia may result from a host immune response and may suggest a favourable clinical course of this type of tumour.

Thymic malignancies

Thymomas and thymic carcinomas are unique tumors of the anterior mediastinum. The association of a variety of different paraneoplastic syndromes with such lesions has fascinated physicians and researchers for years. Most recently, it has been demonstrated by numerous authors that thymomas are chemosensitive tumors. Their indolent nature and relative rarity have made evaluation through prospective randomized clinical trials extremely difficult. Further information regarding the molecular nature of these neoplasms and immunologic aspects is needed in future investigation.

Detection of Epstein-Barr virus in tonsillar tissue of children and the relationship with recurrent tonsillitis

Recurrent tonsillitis has been the subject of much investigation. Events considered to predispose to or cause recurrent tonsillitis (RT) include the misuse of antibiotic therapy in acute bouts, alterations in the microflora, structural changes in crypt epithelium and certain viral infections. Epstein-Barr Virus (EBV) infection usually occurs in early childhood and can persist in palatine tonsil lymphocytes to induce tonsillitis at a later date. We have examined the presence of EBV in palatine tonsils in order to assess the relationship between this virus and recurrent acute tonsillitis. Tonsils were obtained from 85 patients, 2--14 years old (mean 5.6 years old) who underwent tonsils and adenoid (T&A) removal because of recurrent tonsillitis (RT) or T&A hypertrophy (TH). Tissues specimens were processed for non-isotopic in situ hybridization (ISH) using EBER 1/2 oligonucleotides (EBER RNA). The indications for surgery were RT in 42 patients and TH in 43 patients. In 25 out of 85 cases (29.4%) a positive EBER RNA reaction (15 RT and 33 TH) was found. The chi(2)-test showed no statistically significant difference in frequency of positive results between RT and TH group. We conclude that tonsils of children can be colonized by EBV and that the virus may be implicated in RT and TH.

Lymphoepithelioma-like carcinoma of the breast: lack of evidence of Epstein-Barr virus infection

AIMS

Six cases of lymphoepithelioma-like carcinomas of the breast were studied in order to better define the morphology of this type of breast tumour and to see if these neoplastic lesions are related to Epstein-Barr virus (EBV) infection by analogy with histologically similar tumours located in other organs.

METHODS AND RESULTS

The cases were studied with immunohistochemistry using several antibodies and with in-situ hybridization method employing different types of nucleotides in four cases. The cases presented the distinctive morphology of the lymphoepithelioma-like carcinomas as seen in other organs. Specifically Rigaud and Schminke's patterns of growth were observed. In addition, at the edge of the neoplastic lesions, a lymphoepithelial lobulitis was seen. In-situ hybridization failed to reveal any positivity for EBV genome.

CONCLUSION

Lymphoepithelioma-like carcinoma is a specific type of breast tumour, but its relation to EBV has yet to be proven. The differential diagnosis with medullary carcinoma is discussed.

Association of Epstein-Barr virus with lymphoepithelioma-like carcinoma of the lung in southern China

Having reviewed the data on 3,663 consecutive cases of primary lung carcinoma in southern China, we found that 32 cases could meet the criteria for lymphoepithelioma-like carcinoma (LELC) of the lung. To study the relationship between pulmonary LELC and Epstein-Barr virus (EBV) infection, we used in situ hybridization and immunohistochemistry techniques to detect the EBV-encoded small nonpolyadenylated RNA (EBER), latent membrane protein 1 (LMP1), and viral capsid antigen (VCA) in 32 cases of LELC and 19 cases of non-LELC lung carcinoma. Of the 32 cases, 30 (94%) showed EBER positivity. Of the 30 EBER-positive pulmonary LELC cases, 16 and 7 expressed LMP1 and VCA, respectively. In contrast with LELC, none of the 19 cases of non-LELC lung carcinoma showed EBER-, LMP1-, or VCA-positive signals in carcinoma cells. The results demonstrate that there is a close relationship between EBV infection and pulmonary LELC. EBV infection may have an essential role in the tumorigenesis of pulmonary LELC. EBV latent infection is the main status in pulmonary LELC except for individual EBV entering into a lytic cycle.

Epstein-Barr virus--positive undifferentiated thymic carcinoma in a 12-year-old white girl

Thymic epithelial malignant diseases are extremely rare in children. The authors report a 12-year-old white girl admitted for a polymetastatic tumor of the anterior mediastinum. Tumor proliferation was typical of an undifferentiated thymic carcinoma. A close link between Epstein-Barr virus (EBV) and the tumor was established by a high titer of anti-VCA IgA and the presence of EBV RNA and DNA in the tumor. In addition, monoclonal viral episomes were present in tumor cells, indicating that EBV infection was an early event in the oncogenic process. The patient died despite resection, irradiation, and chemotherapy.

Lymphoepithelioma-like carcinoma of the skin with apparent origin in the epidermis--a pattern or an entity? A case report

BACKGROUND

Lymphoepithelioma-like carcinoma (LELC) is prototypically represented by "undifferentiated" nasopharyngeal carcinoma, but it has also been described in many other anatomic locations, including the skin. In the last of these sites, primary LELC has been assumed in the past to show dermal adnexal differentiation.

METHODS

The authors present a case wherein LELC of the skin (LELCS) instead appeared to be a morphologic manifestation of squamous carcinoma of the skin surface, as supported by the results of immunohistology and in situ hybridization.

RESULTS

Like other examples of LELCS, it showed no evidence of integration of the Epstein-Barr viral genome, and its behavior was indolent.

CONCLUSIONS

The heterogeneous nature of LELC as seen in different body sites is reviewed in this report, resulting in the conclusion that this tumor probably represents a morphologic pattern rather than a distinct clinicopathologic entity.

In situ detection of Epstein-Barr virus in breast cancer

Epstein-Barr virus (EBV) is strongly associated with nasopharyngeal carcinoma and some lymphoepithelioma-like carcinomas from other anatomic sites. This study investigates the presence of EBV in breast cancer. Immunohistochemistry for EBV proteins (EBV nuclear antigen-2 and latent membrane protein-1) and in situ hybridization for EBV-encoded small nuclear RNAs (EBER-1 and -2) were performed in 60 invasive breast cancers. None of the 60 breast cancer samples showed detectable EBV. These results suggest that EBV may not play a significant role in the etiology of breast cancers in Taiwan.

EBER oligonucleotide RNA in situ hybridization in EBV associated neoplasms

In virus associated diseases identification of viruses in cells can contribute to the understanding of the pathogenesis and may also help to establish the diagnosis. In the present communication, the effects of the microwave pretreatment (MWP) and that of the proteinase-K enzymatic predigestion (PKD) on EBER RNA oligonucleotide in situ hybridization (EBER-RNA-ISH) (EBER: Epstein-Barr-Encoded-(Early)-RNA) were studied. The efficacy of two EBV detecting methods, latent membrane protein-1 (LMP-1) immunohistochemistry and EBER-RNA-ISH were also compared. Our results show that microwave pretreatment enhances the intensity of the ISH signals and preserves significantly better the structure of the tissues compared with enzymatic predigestion. EBER-RNA-ISH, mainly in the nasopharyngeal carcinoma cases, showed a more frequent positivity than the immunohistochemical reaction for LMP-1, however in case of the Warthin's tumor only the LMP-1 protein was expressed.

Clinicopathological consultation. Lymphoepithelial carcinoma of the larynx hypopharynx, and trachea

Lymphoepithelial carcinoma of the larynx, hypopharynx, and trachea is a rare neoplasm composed of large, poorly differentiated, nonkeratinized cells intermingled with small nonneoplastic lymphocytes and plasma cells. It is histologically similar to its more common counterpart occurring in the nasopharynx. In contrast to nasopharyngeal carcinoma, most cases have not been associated with Epstein-Barr virus (EBV), although rare cases have been reported to be EBV-positive. The diagnosis often requires immunohistochemistry or electron microscopy for confirmation. The neoplasm seems to behave in a fashion reminiscent of nasopharyngeal carcinoma. Lymph node metastasis occurs in the majority of patients, and eventual visceral dissemination occurs in one fourth. Radiotherapy is the main treatment for the primary tumor and regional metastases, but chemotherapy is indicated for more advanced disease. The initial stage is the primary determinant of prognosis. Death from disease occurs in about one third of patients.

Absence of Epstein-Barr virus in lymphoepitheliomalike carcinoma of the skin. Polymerase chain reaction evidence and review of five cases

Lymphoepithelioma is a lymphocyte-rich, poorly differentiated, nonkeratinizing carcinoma of the nasopharynx with distinctive clinical, epidemiologic, and etiologic features. Histologically and immunophenotypically identical tumors arising outside the nasopharynx are designated lymphoepitheliomalike carcinomas (LELCs), and have been described in the gastrointestinal tract, lung, salivary glands, thymus, and increasingly in the skin. Despite similarities between LELC and nasopharyngeal lymphoepithelioma, there is growing evidence that they are etiologically distinct. Serologic studies and molecular techniques have consistently demonstrated an etiopathologic association between Epstein-Barr virus (EBV) and lymphoepithelioma and LELC of several locations, including stomach, salivary gland, lung, and thymus. Though histologically similar. lymphoepitheliomalike carcinoma of the skin (LELCS) does not contain EBV DNA by RNA in situ hybridization. Recently, techniques for polymerase chain reaction (PCR) using fixed tissue have been described that to our knowledge have not been applied to LELCS. We studied five cases of LELCS, taking advantage of the higher sensitivity of PCR to evaluate the role, if any, of EBV specifically in the pathogenesis of LELCS.

Epstein-Barr virus in tumours

The Epstein-Barr virus (EBV) is the best characterized human virus known to infect most people all over the world. In most cases, primary infection with EBV is asymptomatic and the virus persists life-long without causing any disease. The availability of sensitive detection methods, however has led to the identification of a wide array of EBV-associated disease entities. Although nearly 9000 publications have been written since the first description of this virus in 1964, many questions concerning its function and infection patterns remain unanswered. The direct involvement of EBV in the pathogenesis of a disease has only been established for infectious mononucleosis and lymphoproliferative disorders in the setting of congenital or acquired immunodeficiency. Extensive investigations on the role of EBV infection in the pathogenesis of all other EBV-associated lymphoid and epithelial proliferations have led to the conclusion that EBV is not the primary causative agent but it can promote tumour development. Since the early steps in neoplastic development are difficult to assess, further studies are required to clarify the precise role of EBV infection. Furthermore, the clinical significance of the presence of EBV in neoplasia is largely unknown.

Expression of Epstein-Barr virus in carcinomas of major salivary glands: a strong association with lymphoepithelioma-like carcinoma

To elucidate the role of Epstein-Barr virus (EBV) in salivary gland carcinomas, 56 cases of carcinomas of major salivary glands were investigated. These included 14 mucoepidermoid carcinomas, 13 adenoid cystic carcinomas, seven malignant mixed tumors, four adenocarcinomas, four salivary duct carcinomas, two acinic cell carcinomas, two undifferentiated carcinomas without lymphoid stroma, seven lymphoepithelioma-like carcinomas (LELCs), two squamous cell carcinomas, and one small cell carcinoma. EBV transcripts were examined by in situ hybridization using digoxigenin-labeled oligonucleotide antisense probe for EBV-encoded RNA 1 (EBER1) on formalin-fixed paraffin-embedded tissue sections. EBER1 was detected in the malignant epithelial cells in all seven cases of LELC, but not in any of the other carcinomas and the neighboring normal salivary gland tissue. Because all the EBV-negative cases showed satisfactory labeling with the poly d(T) probe, the negative reaction with EBER1 was unlikely to be caused by poor RNA preservation in the tissues. The seven cases of LELC, which were histologically indistinguishable from undifferentiated nasopharyngeal carcinoma (NPC), had a disease-free 4-year survival rate of 85.7%. The results suggest that LELC of the salivary gland in Taiwanese Chinese may share similar EBV-related pathogenesis with that of NPC.

Epstein-Barr virus infection is an early event in gastric carcinogenesis and is independent of bcl-2 expression and p53 accumulation

Ninety-five cases of adenocarcinoma of the stomach were evaluated for the presence of Epstein-Barr virus (EBV) using a sensitive in situ hybridization assay targeting Epstein-Barr virus-encoded RNA 1 (EBER1) transcripts. EBER1 was detected in 11 of 95 (12%) of cases. When present, the virus was localized to malignant epithelial cells and to dysplastic gastric epithelium, but was not seen in normal-appearing gastric epithelium or intestinal metaplasia. The EBV DNA was monoclonal in all three cases tested by Southern blot analysis of the EBV terminal repeat fragment. These findings suggest that the virus was present before malignant transformation. The presence of EBV was strongly associated with increased numbers of tumor-infiltrating T lymphocytes; however, EBV was not associated with prolonged survival. Neither p53 nor bcl-2 were consistently detected in the EBV-associated tumors. Specifically, 6 of 11 EBV-positive carcinomas had accumulation of p53 protein by immunohistochemical analysis, which was similar to the prevalence of p53 accumulation in EBV-negative specimens and suggests that EBV infection does not substitute for p53 mutations during tumorigenesis. The bcl-2 oncoprotein was expressed in a third of the carcinoma specimens tested, but bcl-2 expression did not correlate with the presence of EBV or with expression of EBV latent membrane protein 1. In conclusion, EBV infection appears to precede malignant transformation in a significant fraction of gastric carcinomas, but neither bcl-2 expression nor p53 accumulation appear to be consistently associated with the presence of the virus.

Undifferentiated carcinoma of the parotid gland in a white patient: detection of Epstein-Barr virus by in situ hybridization

Paraffin sections of an undifferentiated salivary gland carcinoma of lymphoepithelioma type, arising in a white (Greek) patient and confirmed by immunohistochemistry, were examined for the presence of Epstein-Barr virus (EBV), using in situ hybridization to detect EBV-specific EBER1 message. Epstein-Barr virus was detected in malignant epithelial cells, but was not found in lymphoid stroma or in residual benign salivary epithelium. These results confirm the existence of an association between EBV and tumor cells of undifferentiated carcinoma of parotid gland. This is the first demonstration of EBV in a salivary gland lymphoepithelioma arising in a non-Eskimo, white patient. This finding suggests that the association of EBV with undifferentiated salivary gland carcinoma may exist in geographic regions remote from Greenland.

Epstein-Barr virus is detected in undifferentiated nasopharyngeal carcinoma but not in lymphoepithelioma-like carcinoma of the urinary bladder

The Epstein-Barr virus (EBV) is associated with nasopharyngeal carcinoma (NPC) and with lymphoepithelioma-like carcinomas developing in certain anatomic sites. In this study, an in situ hybridization was used to identify EBV-encoded ribonucleic acid (RNA) (EBER1) transcripts in 32 of 45 cases of NPC but not in any of the 11 lymphoepithelioma-like carcinomas developing in the urinary bladder. EBER1 was most commonly detected in those NPCs having undifferentiated or nonkeratinizing squamous histology rather than the keratinizing squamous cell subtype of NPC. The EBV-encoded latent membrane protein 1 (LMP1) was expressed focally in only seven of 21 EBER1-positive NPCs by an immunohistochemical technique. These findings imply that EBER1 hybridization is more sensitive than LMP1 immunohistochemistry on paraffin sections in detecting carcinoma-associated virus. Previous in vitro studies have suggested that LMP1 expression might be a function of differentiation, but this study of naturally infected NPCs showed no strong correlation between LMP1 positivity and degree of tumor differentiation, albeit a limited spectrum of differentiation that could be examined. In two cases in which frozen tissue was available, the NPCs were monoclonal with respect to viral DNA structure, implying that the virus was present before malignant transformation. Unlike NPCs, the lymphoepithelioma-like carcinomas of the bladder were uniformly EBV negative, lending further evidence to the growing body of literature linking EBV with lymphoepithelial carcinomas of foregut-derived tissues but not with similar-appearing tumors developing in other anatomic sites.