Lymphoepithelial duct lesions in Sjogren-type sialadenitis

It is not clear, whether the so-called basal cells of the salivary striated ducts are an independent cell-type distinct from myoepithelial cells, maki ng characterization of the cell proliferation typical of the duct lesions i n Sjogren-type sialadenitis/benign lymphoepithelial lesion (BLEL) difficult . An immunohistochemical investigation including different cytokeratin subt ypes, alpha-actin, Ki-67 and Bcl-2 was directed at the epithelial cytoskele ton in normal parotid parenchyma (n=8), BLEL (n=12), HIV-associated lymphoe pithelial cysts (n=8) and palatine tonsils (n=8). There are profound morpho logical and functional differences between basal and myoepithelial cells in the normal salivary duct. Development of duct lesions in BLEL arises from basal cell hyperplasia of striated ducts with aberrant differentiation into a multi-layered and reticulated epithelium, characterized by profound alte ration of the cytokeratin pattern. This functionally inferior, metaplastic epithelium is similar to the lymphoepithelial crypt epithelium of palatine tonsils. The often postulated participation of myoepithelial cells in duct lesions of Sjogren disease/BLEL cannot be supported. We regard the designat ions lymphoepithelial lesion and lymphoepithelial metaplasia as the most ap propriate.