HIV-ASSOCIATED CYSTS OF THE PAROTID-GLAND S - A STUDY WITH HISTOMORPHOLOGY AND MAGNETIC-RESONANCE-IMAGING ADDRESSED TO FORMAL PATHOGENESIS

Background: Multiple and bilateral parotid Lymphoepithelial cysts (LEC ) are encountered in 3-6% of HIV-infected patients. The formal pathoge nesis of LEC is controversial. They are thought to develop from embryo logical salivary gland inclusions in intraparotid lymphnodes. Methods: Seventeen operative parotid specimens from HIV-infected patients were examined histologically and immunohistologically. Findings of magneti c resonance imaging (MRI) were correlated with the histological result s. Results: A continuous spectrum of a lymphoepithelial salivary gland lesion is found, developing initially from a lymphoid infiltration of salivary lobules to lymphoepithelial duct lesions with cystic dilatat ion up to large ductal cysts (diameter up to 3.5 cm) with high-grade p arenchymal atrophy. The ductal and cystic lesions demonstrate an inten se basal cell hyperplasia without participation of myoepithelial cells . The MRI findings indicate involvement of the entire tissue of both p arotid glands. Conclusions: The prefered hypothesis of a development o f HIV-associated Lymphoepithelial cysts from preexisting salivary lymp hnode inclusions cannot be verified. Our results demonstrate a continu ous development of the cysts from a Sjogren-like cystic lymphoepitheli al lesion of parotid glands. The enormous cystic dilatation of the duc t lesions presumably is a consequence of ductal obstruction through ba sal cell hyperplasia of striated ducts and intense intraglandular lymp hofollicular hyperplasia.