[Undifferentiated epithelioma of the parotid and cystadenolymphoma. Apropos of a case].

A case of undifferentiated epithelioma of the left parotid gland occurred 2 years after the removal of a cystadenolymphoma in the right parotid gland. The relationship of these two tumours was supported by several statements: the immunohistochemical study demonstrated in the epithelial cells of the 2 neoplasms the existence of ACE, usually thought as characteristic of cystadenolymphoma. Besides, it showed a high number of plasma cells secreting IgA in the stroma of the 2 tumours, the ultrastructural study performed on the epithelioma also demonstrated some similarities between epitheliomatous cells and epithelial cells of cystadenolymphomas (outlined epidermoid or glandular differentiation, numerous mitochondria). A peculiar, perhaps immunological mechanism could induce the cancerization, according to the theories used to explain the histogenesis of cystadenolymphoma.