Lymphoepithelial Carcinoma Of Salivary Glands: A Clinicopathological And Pathogenetic Study

Lymphoepithelial carcinomas(LEC) of the salivary glands is a rare tumor, the incidence of which is highest among the Inuit of Greenland and North America. There is also a relatively geographic concentration among southern Chinese population. Although there have been several reports on this tumor, however, most of them were in forms of case reports and even less with good follow-up information. The etiology and pathogesis of the tumor is still unclear, To this end, 42 cases of Lymphoepithelial carcinomas of the salivary glands in Sichuan Chinese patients are presented here to discuss the relationship between pathologic features and prognosis and To determine the prevalence of Epstein-Barr virus(EBV) infection in lymphoepithelial carcinomas of salivary glands in Sichuan Chinese and discuss the role of EBV infection in pathogenesis of LEC.A clinicopathologic study of 42 cases of LEC of the Salivary Glands in Sichuan Chinese patients is reported. Paraffin sections of 14 cases of LEC, 2 cases of lymphoepithelial carcinoma with epi-myoepithelial islands , one case of lymphoepithelial carcinoma with lymphoepithelial cyst, some cases of benign lymphoepithelial lesion(BLEL) and nonspecific chronic sialadenitis were examined by in situ hybridization for EBV encoded small RNA-1(EBER-1) using 30-base synthesized oligonucleotide probe as well as by polymerase chain reaction(PCR) for BamHI-W regein of EBV DNA(123bp). The immunohistochemical staining of Keratin, CEA, Myosin were used in some cases.The 5-year survival rate was 48.03%. The cases with extensive fibrosis had worse prognosis . Strong signals for EBER-1 by ISH were obtained in most of tumor cell nuclei in all examined specimens of LEC(14/14) and lymphoepithelial carcinoma with epi-myoepithelial islands, no matter in benign or malignant areas , there was no significant EBER-1 signals in the tissues of lymphoepithelial carcinoma with lymphoepithelial cyst. PCR demonstrated a DNA fragment of 123bp in 12 cases of LEC(12/14) and 2 cases of lymphoepithelial carcinoma with epi-myoepithelial islands . In contrast, there were no significant ISH/PCR signals in examined BLEL, nonspecific chronic sialadenitis and other types of salivary gland carcinomas. Immunohistochemically, Both carcinoma cellsand epi-myoepithelial island cells were stained positive by antibodies against Keratin and CEA, but the cells did not show any definite stainings for myosin.The results indicate that EBV infection is quite specific to lymphoepithelial carcinoma and EBV plays an important role in the pathogenesis of LEC of salivary glands in SiChuan Chinese. LEC and Benign lymphoepithelial lesion(BLEL) develop through etiologically different processes. A few cases of LEC may occur based on BLEL if there is EBV infection or based on lymphoepithelial cyst. But maybe the latter do not share the same pathogenic process with the other LEC. In generally, LEC of salivary glands develop de nove and may arise from duct epithelial cells. Histopathologically, the classification into the two subtype—LEC with extensive fibrosis and LEC with minimal fibrosis(dense lymphocytic infiltration) is valuable in evaluation of prognosis of the tumor. In situ hybridization for EBER-1 and PCR for BamHI-W regein of EBV DNA are useful tool in differential dignosis.