Light and ultrastructural features of lymphoepithelial lesions of the salivary glands in Mikulicz's disease.

This investigation deals with the histogenesis of the so-called 'epimyoepithelial islands' in Mikulicz's disease of the major salivary glands and is based on light and electron microscopic study in six patients. The 'epimyoepithelial islands' represent collapsed acini prior to their complete involution and disappearance, the intraductal cellular proliferation, stratification and differentiation into luminal and peripheral myoepithelial cells with partial and complete obliteration of their lumina and finally, cord-like proliferation and formation of nests of residual pluripotential cells showing squamous metaplasia and occasional myoepithelial cell differentiation. A pink, homogeneous and hyaline material on light microscopic examination is multilayered and extracellular and is in close association with the basal lamina when viewed with electron microscope.