Gastric Carcinoma With Lymphoid Stroma Research Articles

Epstein–Barr virus-associated gastric adenosquamous carcinoma with concurrent gastric carcinoma with lymphoid stroma: a case report and review of the literature

BackgroundAdenosquamous carcinoma (ASC)with concurrent gastric carcinoma with lymphoid stroma (GCLS) are extremely rare tumors. There are only limited cases reported in the literature. Epstein–Barr virus (EBV) infection was found in the concomitant GCLS, but none in the ASC. Here, we report the first case of gastric cancer with EBV infection detected in both ASC and GCLS.Case presentationA 59-year-old man complained of intermittent upper abdominal pain. The gastric endoscopy revealed a type IIc tumor located in the gastric body near the fundus of the stomach. Histological examination of the gastric tumor showed the coexistence of ASC and GCLS. Both components were positive for EBV-encoded RNA (EBER) in situ hybridization. Neoplastic nests of the former were positive for p63, p40 and CK5/6. The glandular components showed positive acid mucus in the Alcian-blue periodic-acid-schiff (AB-PAS) staining. There was significant difference in the expression of epidermal growth factor receptor (EGFR) between adenocarcinoma and squamous carcinoma, but not in other proteins such as human epidermal growth factor receptor 2 (HER2), p53 and mismatch repair proteins. The role of EGFR signaling pathway needs to be further explored in the differentiation of squamous carcinoma in the gastric ASC. Finally, a diagnosis of early EBV associated gastric ASC with concurrent GCLS (pT1bN1) was made. The patient took a single-drug S1 periodically for half a year after the surgery and has been disease free during 8 months of medical follow-up.ConclusionsThis is the first case of EBV associated gastric ASC with concurrent GCLS, and pathologists and clinicians should recognize and pay attention to this type of tumor.

Epstein–Barr Virus Positive Gastric Cancer: A Distinct Subtype Candidate for Immunotherapy

BackgroundEpstein–Barr virus (EBV) positive gastric cancer (GC) has been described as a distinct molecular subtype of the disease, especially associated with gastric carcinoma with lymphoid stroma (GCLS). The possibility that EBV associated GC (EBVaGC) had better prognosis and may be susceptible to immunotherapy has increased the interest in this subtype. However, immune checkpoint and survival of EBVaGC are still controversial, especially with regard to GCLS and conventional gastric adenocarcinoma (CGA). This study aimed to evaluate the clinicopathological characteristics, immunohistochemical profiles and prognosis of EBVaGC according to the histological type GCLS and CGA. Methodswe retrospectively evaluated a series of EBVaGC who underwent gastrectomy with D2-lymphadenectomy. Biomarkers and tumor-infiltrating cells were evaluated by immunohistochemistry. PD-L1 was evaluated using a combined positive score (CPS). ResultsFrom a total of 30 EBVaGC, 14 (46.7%) were identified as GCLS and 16 (53.3%) as CGA (9 Intestinal, 6 diffuse, 1 undetermined). There were no significant differences in age, sex, and pTNM between GCLS and CGA. CPS-positivity and high-CD8+ was significantly higher in GCLS compared with CGA (P = 0.007 and P = 0.005, respectively). Diffuse EBVaGC had worse survival than intestinal type (P = 0.020). There was no difference in survival between GCLS and intestinal CGA (P = 0.260). In multivariate analysis, CPS and pN status were related with survival in EBVaGC. ConclusionsCGLS was associated with a predominance of CD8+ cell infiltration and PD-L1 expression. CPS and lymph node metastasis were independent factors associated with prognosis in EBVaGC. These results suggest that specifically EBV-positive GCLS may be prime candidates for PD-1 directed therapy.

Gastric Carcinoma with Lymphoid Stroma: A Rare Case Report with EBV Negativity

Abstract Introduction/Objective Gastric carcinoma with lymphoid stroma (GCLS) is a distinct and rare histologic subtype of gastric adenocarcinoma that is characterized by undifferentiated carcinoma mixed with prominent lymphoid cell infiltration. Around 80% of GCLS cases are associated with Epstein-Barr virus (EBV) infection. Here we report a case of EBV-negative GCLS. Methods The patient was a 79-year-old female with a recent history of abdominal distention, weight loss, and gastrointestinal bleeding who presented for evaluation. Endoscopy found a 4.6 mm lobulated lesion at the incisura of the stomach with endosonographic evidence of invasion through the submucosa. Biopsy was consistent with intramucosal diffuse neoplasm, favoring adenocarcinoma. The decision was made to do subtotal gastrectomy. Results The patient underwent distal gastrectomy with Billroth 2 reconstruction. Gross examination of the stomach revealed a firm 1.4 cm nodule in the background of diffuse mucosal granularity in the adjacent stomach. Microscopically, the tumor invaded the submucosa without lymph nodes involvement. Staining showed the tumor diffusely positive for CAM5.2, focally and weakly positive for pancytokeratin and CK7, while negative for CK20. Mismatch repair (MMR) proteins staining demonstrated a loss of nuclear expression of MLH1 and PMS2. Her2/Neu FISH was non-amplified. The tumor was found to be EBV negative by EBER ISH while PD-L1 was expressed. The histopathological findings confirmed the final diagnosis of gastric carcinoma with lymphoid stroma (GCLS). Conclusion We report a case of GCLS that was EBV negative with non-amplified HER2, while MMR-deficient, and PD-L1 positive. These results suggest that this tumor subtype may be less responsive to targeted therapy, but show susceptibility to immune checkpoint inhibitors.

Clinical impact of Epstein-Barr virus status on the incidence of lymph node metastasis in early gastric cancer.

Epstein-Barr virus-positive gastric cancer (EBVGC) comprises approximately 9% of all gastric cancers and is associated with a low prevalence of lymph node metastasis (LNM). Given that limited data concerning LNM in EBV-related early GC are available, EBV status is not considered an indicator for endoscopic submucosal dissection (ESD). In this review, we focused on pT1 EBVGC and on gastric carcinoma with lymphoid stroma (GCLS), and discuss expanded ESD indications and curative resection criteria. In pT1b EBVGC, the incidence of LNM was low (6/180 patients, 3.3%; 95% confidence interval [CI] 1.2-7.1), especially in lymphovascular invasion-negative EBVGC (1/109 patients, 0.9%). No patients with pT1a EBVGC had LNM (0/38 patients, 0%; 95% CI 0-7.6), even those who did not meet the current curative ESD criteria. Although the frequency of LNM in GCLS was low (5.0-10.6%), the incidence of LNM in non-EBV GCLS was relatively high (10.0-20.0%); therefore, EBV status can be considered a more important factor than GCLS. In summary, the clinicopathological characteristics of EBVGC differ from those of conventional GC, and EBV negativity is a risk factor for LNM in early GC. Therefore, patients in this group are likely to be promising candidates for ESD, and we recommend that EBV status evaluation be included in early GC treatment guidelines.

Simultaneous gastric adenosquamous carcinoma and gastric carcinoma with lymphoid stroma: A case report.

Primary gastric adenosquamous carcinoma (ASC) is a rare tumor, and gastric carcinoma with lymphoid stroma (GCLS) is a distinct and relatively rare tumor, which is characterized histopathologically by prominent lymphoid infiltration and is commonly associated with Epstein-Barr virus (EBV) infection. The association between ASC and GCLS has been poorly understood, and only two cases of concomitant occurrence of ASC and GCLS have been reported previously. In this report, we describe the first documented case of simultaneous gastric ASC and GCLS. A 58-year-old Japanese male complained of loss of appetite. Gastric endoscopic examination revealed a type 3 tumor in the antrum. Distal gastrectomy with lymph node dissection was performed after neoadjuvant chemotherapy. Macroscopic examination of the resected specimen revealed two discontinuous lesions in the antrum. The first lesion, an ASC, was detected preoperatively by endoscopic examination. This type 3 tumor was composed of a mixture of squamous cell carcinoma (~75% of the tumor) and poorly-to-moderately differentiated adenocarcinoma (~25%). No EBV-encoded RNA (EBER)-positive neoplastic cells were noted. The tumor had invaded into the serosa. The second lesion was a GCLS, which was not preoperatively detected by endoscopic examination. The neoplastic cells of the GCLS were EBER-positive. The tumor had invaded into the muscularis propria. Accordingly, a diagnosis of simultaneous gastric ASC (pT4a) and GCLS (pT2) was made. The pathogenesis of gastric ASC has been under debate. Only limited cases of ASC associated with EBV have been reported. Notably, EBV has not been associated with the development of an ASC component in the previously reported concomitant cases of ASC and GCLS, as well as in the present case study. Therefore, additional studies are required to clarify the pathogenesis of gastric ASC, including its association with EBV.

A Single-Center Experience of Endoscopic Resection for Early Gastric Cancer with Lymphoid Stroma.

PurposeThis study aimed to evaluate immediate outcomes and clinical courses of patients with early gastric carcinoma with lymphoid stroma (GCLS) who underwent endoscopic resection.Materials and MethodsWe retrospectively reviewed the medical records of 40 patients (mean age, 56.9 years; 90.0% male) who underwent endoscopic resection and were pathologically diagnosed with GCLS confined to the mucosa or to the submucosa between March 1998 and December 2017.ResultsForty GCLS lesions in 40 patients were treated using endoscopic resection. Only 4 (10%) patients received diagnosis of GCLS before endoscopic resection. Fourteen (35.0%) lesions were intramucosal cancers and 26 (65.0%) exhibited submucosal invasion. En bloc resection (97.5%) was achieved for all lesions except one, with no significant complications. The complete resection rate was 85.0% (34 of 40 lesions). After endoscopic resection, 17 patients were referred for surgery and underwent gastrectomy with lymph node (LN) dissection because of deep submucosal invasion (n=16) and misclassification as undifferentiated cancer (n=1). No LN metastasis was determined in the specimens obtained during surgery. During a mean follow-up period of 49.7 months for 23 patients without surgical treatment, no regional LN enlargements, distant metastases, or gastric cancer-related deaths were found, although 1 metachronous lesion (undifferentiated adenocarcinoma, follow-up duration: 7 months) was observed.ConclusionsIn patients with early GCLS, endoscopic resection is technically feasible and has favorable clinical outcomes. Therefore, endoscopic resection might represent an alternative treatment modality in patients with early GCLS with a low likelihood of LN metastasis.

Clinicopathologic features of early gastric carcinoma with lymphoid stroma and feasibility of endoscopic submucosal dissection.

Gastric carcinoma with lymphoid stroma (GCLS) is a rare disease known to have unique features and a favorable prognosis. This study aimed to determine the clinicopathologic features of early GCLS (EGCLS) and define the feasibility of endoscopic submucosal dissection (ESD) for EGCLS. We performed a retrospective analysis of 70 EGCLS patients treated via ESD or surgery and 1626 patients who underwent surgical resection for early non-GCLS (ENGCLS) between January 2007 and December 2014 at Pusan National University Hospital, Busan, Republic of Korea. The mean age of EGCLS patients was 58years (range 36-77years); a male predominance (3.7:1) was observed, and 81.4% showed Epstein-Barr virus positivity. Compared with ENGCLS, EGCLS was macroscopically more elevated (34.3 vs. 18.0%, P = 0.003) and located more proximally (upper third: 37.1 vs. 9.7%, P < 0.001). Tumor size was smaller (2.1 ± 1.1 vs. 3.1 ± 2.0cm, P < 0.001), but submucosal invasion was more frequent (77.1 vs. 44.4%, P < 0.001) and deeper in the EGCLS group. Among the 59 EGCLS patients who were treated surgically, only two (3.4%) showed lymph node metastasis (LNM). Despite submucosal invasion, EGCLS showed a lower LNM rate (4.0 vs. 19.4%, P = 0.007) than ENGCLS, even in patients with SM3 EGCLS (5.3 vs. 24.5%, P = 0.007). There were no recurrences in the available ten patients who underwent ESD alone during a mean follow-up of 37.2months. In this study, we observed unique clinicopathologic features with a very low LNM rate in EGCLS. We consider ESD a potentially curative treatment strategy for EGCLS despite deep submucosal invasion, especially in patients with poor performance status and significant comorbidities.

Aberrant expression of AID and AID activators of NF-κB and PAX5 is irrelevant to EBV-associated gastric cancers, but is associated with carcinogenesis in certain EBV-non-associated gastric cancers.

Epstein-Barr virus-associated gastric carcinoma (EBVaGC) is a distinct subtype of gastric cancer characterized by clinicopathological features including lymphoepithelioma-like histology. Aberrant expression of activation-induced cytidine deaminase (AID) as a genomic modulator was demonstrated through pathogen-related nuclear factor κB (NF-κB) signaling in Helicobacter pylori-associated gastric cancer. To elucidate whether or not AID expression is relevant to carcinogenesis in EBVaGC, immunohistochemical expression of AID and AID-regulatory factors between EBVaGC and EBV-non-associated gastric carcinoma (GC) were evaluated, each using 15 cases of GC with lymphoid stroma (GCLS) and other types of GC. Aberrant expression of AID, NF-κB and paired box 5 (PAX5) were significantly decreased in EBVaGC (0/11, 1/11 and 1/11) compared with in EBV-non-associated GC (7/19, 12/19 and 11/19) (P=0.025, 0.005 and 0.01, respectively); however, no significant difference in c-Myb proto-oncogene expression was identified. AID expression was also decreased in EBV-associated GCLS (0/10) compared with in EBV-non-associated GCLS (3/5). Unexpectedly, decreased expression of NF-κB and PAX5 was observed in GCLS (1/15 and 2/15) compared with in GC without LS (12/15 and 10/15) (P<0.001 and P=0.003, respectively). Decreased AID expression observed in EBVaGC is consistent with the reported molecular characterization of hypermethylation and rare somatic gene mutation in EBVaGC. Only PAX5 was identified to be significantly associated with venous invasion (P=0.022). The results of the present study suggest that pathogen-induced AID expression may be irrelevant to carcinogenesis of EBVaGC, whereas it contributes to carcinogenesis in certain types of EBV-non-associated GC.

Clinical application of early gastric carcinoma with lymphoid stroma based on lymph node metastasis status.

Gastric carcinoma with lymphoid stroma (GCLS) is characterized by undifferentiated carcinoma mixed with prominent lymphoid infiltration. GCLS has unique clinicopathological features and a better prognosis compared to other types of gastric cancer. We analyzed the clinicopathological features of early GCLS in relation to lymph node metastasis (LNM). We performed a retrospective analysis of 241 patients diagnosed with GCLS confined to the mucosa or the submucosa between March 1998 and December 2015. Their data were compared with those from 1219 patients who underwent resection for differentiated early gastric cancer (EGC). Of the 241 patients analyzed, 33 (13.7%) had intramucosal cancers and 208 (86.3%) had cancers that penetrated the submucosa. Compared to differentiated EGC, early GCLS was more prevalent in younger individuals and in men, tended to be proximally located, was highly associated with Epstein-Barr virus (EBV) infection (89.2%), and had a lower risk of LNM. The 5-year disease-specific survival rate of patients with early GCLS was 98.3% but depended significantly on LNM status (p<0.001) and EBV infection status (p=0.039). The risk of LNM from mucosal GCLS and submucosal GCLS was 0% [95% confidence interval (CI) 0-9.1] and 10% (95% CI 6.8-15.2), respectively. On multivariate analysis, LNM was found to be associated with tumor size (p=0.022) and lymphovascular invasion (p=0.002) in addition to tumor depth. Early GCLS has distinct clinicopathological features depending on age, sex, tumor location, EBV infection status, and LNM status. Tailored therapies, including endoscopic treatment, are needed based on the distinct clinicopathological features of early GCLS.

Clinicopathologic features of gastric carcinoma with lymphoid stroma in early gastric cancer.

Gastric carcinoma with lymphoid stroma (GCLS) is a rare variant of gastric cancer. The aims of this study were to investigate the clinicopathologic features of GCLS in early gastric cancer (EGC). Analysis included 3,385 patients who were diagnosed with EGC after surgery between 2005 and 2012. This study compared GCLS with non-GCLS patients in terms of clinicopathological features including lymph node metastasis (LNM). Forty-one (1.2%) patients were diagnosed as GCLS among those with EGC. When GCLS and non-GCLS patients were compared, the GCLS group showed a greater predominance among males, greater tendency towards proximal location, a more elevated gross appearance, and deeper submucosal invasion. In particular, more than 90% of GCLS cases showed deep submucosal invasion. The LNM rate was significantly lower in GCLS than non-GCLS cases after adjustment for depth of invasion. Among the GCLS group, there was no LNM in the cases with lesions confined to the mucosa or submucosal invasive lesions with tumor size ≤10 mm. In EGC, GCLS showed deeper submucosal invasion and a lower LNM rate compared with non-GCLS. Thus, clinical considerations of GCLS may be helpful to decide on a specific cancer treatment. J. Surg. Oncol. 2016;114:769-772. © 2016 Wiley Periodicals, Inc.

How Does Epstein-Barr Virus Affect Gastric Carcinoma with Lymphoid Stroma?

Gastric carcinoma with lymphoid stroma (GCLS) is an uncommon subtype of gastric adenocarcinoma (GA). More than 80% of GCLS tumors have associated

Features of Gastric Carcinoma With Lymphoid Stroma Associated With Epstein-Barr Virus

Gastric carcinoma with lymphoid stroma (GCLS) is a distinct histologic subtype of gastric cancer that is characterized by undifferentiated carcinoma mixed with prominent lymphoid infiltration. More than 80% of GCLS cases are associated with Epstein-Barr virus (EBV) infection, but it is unclear if the virus affects disease progression. We investigated how EBV infection affects the clinical and pathologic features of GCLS, as well as patients' outcomes. We performed a retrospective analysis of 274 patients (mean age, 56.8 y; 85.4% male) diagnosed with GCLS, based on pathology findings, from March 1998 through December 2012 at the Asan Medical Center in Seoul, South Korea. Their data were compared with those from 822 age- and sex-matched patients who underwent resection for gastric adenocarcinoma. EBV was detected in tumor samples by in situ hybridization. Of the 274 patients with GCLS, 236 had EBV-positive tumors (86.1%) and 38 had EBV-negative tumors (13.9%). EBV-positive GCLS was more prevalent than EBV-negative GCLS in younger patients, tended to be located proximally, and was more frequently of an early stage macroscopic type. The 10-year, disease-specific rates of survival were 89.1% for patients with EBV-positive GCLS and 66.9% for patients with EBV-negative GCLS (P = .009). Patients with EBV-negative GCLS had clinical and pathologic features and survival times similar to those of patients with conventional adenocarcinoma. By multivariate analysis, longer survival time was associated with EBV-positive tumors (P = .007), younger patient age (P = .002), smaller tumor size (P = .046), lower stage (based on American Joint Committee on Cancer classification; P < .001), and lack of lymphovascular invasion (P = .012). The proportion of undifferentiated tumor cells was not associated significantly with patient survival time. Clinical and pathologic features of GCLS differ based on EBV infection status. EBV-negative GCLS is similar to conventional adenocarcinoma, and patients have similar survival times. EBV status may be more important than the proportion of undifferentiated tumor cells in the diagnosis of GCLS and management of patients.

Ezrin expression and its phosphorylation in gastric carcinoma with lymphoid stroma and Epstein-Barr virus infection

Gastric carcinoma with lymphoid stroma (GCLS) is a unique variant of gastric carcinoma that represents prominent lymphocytic infiltration and is correlated with Epstein-Barr virus (EBV) infection. Ezrin expression and activation are crucial in tumor metastasis and induce cell migration of EBV-related nasopharyngeal carcinomas. Using immunohistochemical methods, the expression of total and phosphorylated ezrin (p-ezrin), Thr567, was examined in 104 GCLS cases, including 78 EBV-positive and 26 EBV-negative cases, as well as 29 non-GCLS cases. Positive ezrin expression was detected to be at markedly higher levels in GCLS compared to non-GCLS (P<0.0001). Furthermore, ezrin expression was detected to be at higher levels in EBV-positive compared to EBV-negative GCLS (P=0.0294). High expression of p-ezrin in GCLS was associated with positive lymph node metastasis (P=0.0187). In summary, these results demonstrated that ezrin overexpression is correlated with the histologic characteristics of GCLS and EBV infection. Phosphorylation of ezrin may, therefore, contribute to lymph node metastasis in GCLS.

Epstein–Barr virus in gastric carcinomas with lymphoid stroma

To clarify the relationship between the Epstein-Barr virus (EBV) and gastric carcinoma with lymphoid stroma (GCLS) in Koreans, and to characterize the EBV-positive GCLS. EBV infection was examined using EBER in-situ hybridization and polymerase chain reaction in 45 cases of GCLS among Koreans, and in 292 consecutive cases of gastric carcinomas without lymphoid stroma (non-GCLS) as controls. EBV infection was found in 30 tumours (67%) of GCLS and 10 tumours (3.4%) of non-GCLS (P < 0.05). EBV-positive GCLS was more prevalent in males, poorly differentiated histological type and diffuse type in Lauren's classification, and tended to be located more in the middle third of the stomach than EBV-negative GCLS (P < 0.05). p53 overexpression was observed in 22% of GCLS (17% of EBV-positive GCLS and 33% of EBV-negative GCLS), and 34% of non-GCLS (EBV-positive GCLS vs. non-GCLS: P = 0.056). The survival of the patient with GCLS was not correlated with EBV infection or p53 immunoexpression (follow-up period: 11-97 months). GCLS in Koreans is strongly associated with EBV infection. The prognosis in GCLS is not dependent upon either the status of EBV infection or the status of p53 immunoexpression.

A Case of Early Gastric Carcinoma with Lymphoid Stroma: Diagnostic Usefulness of Endosonography

Abstract: A case of early gastric carcinoma with lymphoid stroma (GCLS) showing features of submucosal tumor is reported here. A characteristic endoscopic ultrasonographic (EUS) finding was helpful for preoperative diagnosis. The patient, a 75‐year‐old woman without any previous complaints, visited our hospital for detailed examination of a small gastric lesion. Upper Gl studies revealed a submucosal tumor‐like lesion measuring about 1.8 cm with a central slight depression on the greater curvature of the middle gastric body. Histologic findings of the specimens obtained by conventional biopsy indicated a poorly differentiated adenocarcinoma, although the possibility of malignant lymphoma was not completely ruled out. EUS examination was, therefore, performed in order to obtain further detailed information about the tumor. EUS disclosed that the tumor, which existed in the third layer, was composed of many small round clustered lesions, the echogenicity of which was lower than that of the muscle layer, and was almost covered with a normal mucosal layer. Taking these findings into consideration, a gastric cancer with lymphoid stroma whose invasion would be limited within the submucosa was highly suspected. It was proven by histological analysis of a surgically resected specimen that this peculiar multiple small round hypoechoic lesion was equivalent to the lymphoid aggregates infiltrating the GCLS. Since it has been reported that the prognosis of GCLS is better than that of common gastric cancers, accurate diagnosis is important for the selection of optimal treatment. While it is still not definitively proven that EUS is useful for diagnosis of GCLS, this procedure may potentially provide an excellent image of this special tumor and be of use for preoperative diagnosis.

Infrequent overexpression of p53 protein in Epstein-Barr virus-associated gastric carcinomas.

Epstein‐Barr virus (EBV) infection was studied in a total of 412 patients with poorly differentiated gastric adenocarcinoma by in situ hybridization for EBV‐encoded small RNA. EBV‐speciflc RNA was detected in tumor cell nuclei of 83 (20.1%) of 412 gastric carcinomas, of which 60 were histologically subclassified as gastric carcinoma with lymphoid stroma (GCLS). All EBV‐positive gastric carcinomas as well as 90 randomly selected EBV‐negative gastric carcinomas were further studied for p53 protein expression by immunohistocbemistry. The Overexpression of p53 protein was demonstrated in only 7 (8.4%) of 83 EBV‐positive gastric carcinomas. This was in marked contrast to the frequency of 34.4% in EBV‐negative gastric carcinomas. In addition, a few p53‐positive nuclei were characteristically scattered in the tumors of many EBV‐positive GCLS, but this was not regarded as p53 Overexpression arising from mutation of the gene. Our findings suggested that EBV‐associated gastric carcinomas may arise through a different mechanism from other types of gastric carcinomas without EBV infection.

Detection of Epstein-Barr virus DNA in gastric carcinoma with lymphoid stroma.

Gastric carcinoma with lymphoid stroma (GCLS) was considered to be one of the virus-associated neoplasms. However, the precise mechanism of Epstein-Barr virus (EBV) oncogenesis for GCLS remains unclear. We used polymerase chain reaction (PCR) and DNA in situ hybridization (ISH) methods to detect the presence of EBV DNA in 14 cases of gastric carcinoma, including 8 cases of GCLS. Epstein-Barr virus DNA was detected by both PCR and ISH in 3 of the 8 GCLS cases (37.5%) and was negative in the other 6 cases of non-GCLS. In situ DNA hybridization showed that the EBV DNA was in the carcinoma cells in all cases that were positive by PCR. Among the positive cases, one early gastric carcinoma showed that EBV DNA was not only in the carcinoma cells, but also in the normal epithelium. This study provides the interpretation of the finding of EBV DNA in nonneoplastic gastric epithelium. Some genetic changes may be initiated in the EBV-infected nonneoplastic cells, which would lead to oncogenesis.

Low frequency of apoptosis in Epstein-Barr virus-associated gastric carcinoma with lymphoid stroma.

In order to understand the character of Epstein-Barr virus (EBV)-associated gastric carcinoma with lymphoid stroma (GCLS), we examined cell proliferation and death in comparison with gastric carcinoma without prominent lymphoid stroma (conventional gastric carcinoma). The EBV-encoded small RNA I (EBER-1) and apoptotic cells were examined by in situ hybridization (ISH) and by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end-labeling (TUNEL), respectively, on formalin-fixed paraffin-embedded surgical specimens from 22 GCLSs and 23 conventional gastric carcinomas. Immunostaining was performed for the detection of Ki-67 antigen (Ki-67), P53 protein (P53) and bcl-2 oncoprotein (BCL-2). The percentages of apoptotic and Ki-67-positive cells were expressed as apoptotic indices (AI) and Ki-67 labeling indices (KI), respectively. EBER-1 was detected in 19 (86%) GCLSs in contrast to none in conventional carcinomas. Mean AI was 1.8 +/- 0.6 in the EBER-1-positive GCLSs and 3.3 +/- 1.7 in the conventional gastric carcinomas, the value being significantly lower in the former (p < 0.01). Mean KI was 40.0 +/- 10.8 in the GCLSs and 48.5 +/- 9.1 in the conventional gastric carcinomas, the value being significantly lower in the former (p < 0.05). P53 expression showed no significant difference between the 2 categories of carcinoma.

Phenotypic characteristics of Epstein-Barr-virus-associated gastric carcinomas.

We identified Epstein-Barr-virus(EBV)-associated gastric carcinomas by in situ hybridization that targets EBV-encoded small RNA, and investigated their phenotypic characteristics by mucin histochemistry. Out of 132 gastric carcinomas, 15 were EBV-positive, and they were exclusively located at the proximal part of the stomach; 8 were early and 7 were advanced carninomas. Out of the 15 EBV-positive carcinomas, 10 were so-called gastric carcinoma with lymphoid stroma (GCLS); 4 of the other 5 tumours were moderately differentiated adenocarcinoma (tub 2) showing a "lace pattern". This pattern was also seen in the intramucosal parts of 6 (3 early and 3 advanced) GCLS. As for the mucin phenotype of the cancer cells, the gastric type was predominant in the EBV-positive tumours, while the EBV-negative tumours, even with the lace pattern or GCLS, showed phenotypes other than the gastric type (intestinal or mixture of intestinal and gastric). It was inferred that EBV-positive gastric carcinomas show tub 2 with the lace pattern and gastric phenotype in earlier stages, and become GCLS during the tumour progression, but the gastric phenotype tends to remain throughout the history.

Epstein‐Barr virus in gastric carcinoma with lymphoid stroma. Special reference to its detection by the polymerase chain reaction and in situ hybridization in 99 tumors, including a morphologic analysis

Gastric carcinoma with lymphoid stroma (GCLS) has been reported to have a more favorable prognosis than ordinary gastric carcinoma, however, the precise mechanism of the pathogenesis for GCLS remains unclear. The authors analyzed 99 GCLS in 94 patients for Epstein-Barr virus (EBV) sequences using polymerase chain reaction (PCR) and in situ hybridization (ISH); these were compared with 42 ordinary gastric carcinomas. Two series of PCR showed 81 (82%) and 46 (47%) of the 99 GCLS to have EBV sequences, which were significantly higher compared with ordinary gastric carcinoma (50% and 9.5%, respectively). With ISH using thymine-thymine dimerized oligonucleotide probes corresponding to EBV-encoded small RNA 1 (EBER1), 82 (83%) of 99 GCLS showed clear, intense hybridization signals localized over the nuclei of the tumor cells, in contrast to only 4 (9.5%) of 42 ordinary carcinomas (P < 0.001). A comparative morphologic analysis of EBER1-positive and negative GCLS revealed that typical features of GCLS, such as mild cellular pleomorphism, rare mitoses, a marked degree of lymphoid stroma, and mild fibrosis, together with a lymphoid infiltration within the cancer cell nests were significantly more frequent in EBER1-positive GCLS. More than 80% of GCLS were associated with EBV. The presence of EBV association in GCLS was characterized by the above morphologic features.