Characteristics of Epstein-Barr virus-associated gastric carcinoma with lymphoid stroma in Japan

Non-Epstein-Barr virus associated lymphoepithelioma-like carcinoma of the inferior common bile duct

A carcinoma displaying undifferentiated features with dense lymphoplasmacytic infiltration is defined as a lymphoepithelioma-like carcinoma (LEC), and some of LEC is associated with Epstein-Barr virus (EBV). All of the 13 previously reported cases of LEC of the biliary system were intrahepatic in location. Herein, we describe the first case of LEC of the inferior common bile duct. A 68-year-old Japanese man, who had been previously treated for hepatocellular carcinoma using microwave coagulation therapy, was found to have tumors of the common bile duct and pancreas head. Histopathological study of the resected tumor showed solid or cohesive nests of large undifferentiated cells with irregular large vesicular nuclei and nucleoli. Around the tumor cell nests, dense lymphoplasmacytic infiltration was observed. Focal glandular differentiation (approximately 5%) was also present. These histopathological features corresponded morphologically to LEC. Immunohistochemically, the tumor cells were positive for cytokeratin (CK) 7, CK 19 and CA19-9, but negative for CK 20 and Hep Par 1. In situ hybridization for Epstein Barr virus early small RNAs disclosed no nuclear signal in tumor cells. Therefore, a diagnosis of non-EBV-associated LEC of the inferior common bile duct was made. Although the prognosis of the biliary LEC is thought to be better than that of conventional cholangiocarcinoma, the differences in prognosis between EBV-positive and -negative cases have not yet been established. Therefore, additional case studies will be needed to clarify the clinicopathological features of LEC of the biliary tract.

Differential expression of apoptosis related proteins and nitric oxide synthases in Epstein Barr associated gastric carcinomas

AIM: To determine the incidence of Epstein Barr virus associated gastric carcinoma (GC) in Brazil and compare the expressions of apoptosis related proteins and nitric oxide synthases between EBV positive and negative gastric carcinoma.

METHODS: In situ hybridization of EBV-encoded small RNA-1 (EBER-1) and PCR was performed to identify the presence of EBV in GCs. Immunohistochemistry was used to identify expressions of bcl-2, bcl-xl, bak, bax, p53, NOS-1, NOS-2, and NOS-3 proteins in 25 EBV positive GCs and in 103 EBV negative GCS.

RESULTS: 12% of the cases of GC (25/208) showed EBER-1 and EBNA-1 expression. The cases were preferentially of diffuse type with intense lymphoid infiltrate in the stroma. EBV associated GCs showed higher expression of bcl-2 protein and lower expression of bak protein than in EBV negative GCs. Indeed, expressions of NOS-1 and NOS-3 were frequently observed in EBV associated GCs.

CONCLUSION: Our data suggest that EBV infection may protect tumor cells from apoptosis, giving them the capacity for permanent cell cycling and proliferation. In addition, EBV positive GCs show high expression of constitutive NOS that could influence tumor progression and aggressiveness.