[Salivary duct cyst of the parotid gland and adenocarcinoma].

The progression of benign cystic lesions of the parotid gland to malignant tumors is an extremely rare event and has been described only for cystadenolymphomas. Here we present a case of malignant transformation to an adenocarcinoma occurring in ductal cells forming the wall of a parotid retention cyst. In addition to clinical and histological findings, we describe the results of immunohistochemical and molecular analyses providing evidence that the cells undergoing neoplastic transformation were latently infected by Epstein-Barr virus (EBV). These results suggest a possible causal relationship between latent EBV infection and malignant progression.