Lymphoepithelial cysts of salivary glands: an immunohistochemical study of HIV-related and HIV-unrelated lesions.

An indolent lesion of the salivary glands that mimics Sjøgren syndrome has been repeatedly reported in HIV-infected (HIV+) patients. It is characterized by the occurrence, usually in the parotid gland, of variably sized lymphoepithelial cysts (LECs), whose origin is still unclear. We have compared the morphological and immunohistochemical features of six cases of LEC in HIV+ patients with those of five cases of LEC in HIV-negative (HIV-) patients. The results of the study show that LECs have similar histological and immunohistochemical features in both HIV+ and HIV- patients, and that they may simultaneously affect the salivary gland parenchyma and the intrasalivary lymph nodes. Furthermore, a diffuse lymphoid infiltrate is invariably observed in the glandular tissue around LECs and it is consistently associated with ectatic changes of the striated ducts. These data and the finding of an equivalent proliferation fraction of the epithelial compartment in both LEC and salivary retention cysts, used as controls for this study, are consistent with the hypothesis that cyst formation is secondary to the obstruction of salivary ducts by exuberant lymphoid infiltration.