HIV-related parotid lymphoepithelial cysts. Immunohistochemistry and 3-D reconstruction of surgical and autopsy material with special reference to formal pathogenesis.

Whether lymphoepithelial cysts in the parotid glands in HIV-infected patients develop from pre-existing salivary gland inclusions in intraparotid lymph nodes or from a lymphoepithelial lesion of salivary parenchyma is unclear. To examine their pathogenesis we performed a histological and immunohistochemical study of salivary specimens from 100 AIDS patients in different disease stages. There is a continuous morphological spectrum of changes within the salivary parenchyma, starting with lymphoid stroma infiltration and evolving to characteristic lymphoepithelial duct lesions with a immunohistochemically proven basal cell proliferation and to fully developed ductal cysts. Involvement of myoepithelial cells-postulated in comparable Sjögren-associated duct lesions-is excluded immunohistochemically. Computer-assisted 3-D reconstructions confirm an association of the cysts with the intralobular duct system. Our study disproves the prevailing hypothesis, which suggests that the lymphoid cell compartment of HIV-associated lymphoepithelial cysts stems from pre-existing intraparotid lymph nodes. The results demonstrate that a secondary lymphatic infiltration of salivary parenchyma provokes a lymphoepithelial lesion of striated ducts with basal cell hyperplasia. The frequent progression to a multifocal cystic lymphoepithelial lesion may be supported by ductal compression through a high degree of lymphofollicular hyperplasia in early disease.