Attenuated squamous epithelium lines the cyst which is filled with eosinophilic fluid and some foamy macrophages. A dense lymphoid infiltrate underlies the epithelium and also infiltrates the epithelium.
Within the lymphoid infiltrate, germinal centers may form. The infiltrate is polymorphous. Although not seen here, most cysts are surrounded by a fibrous capsule.
Keratin AE1/3 highlights the benign cystic nature of the squamous epithelium.
Lymphoepithelial cysts are associated with human immunodeficiency virus (HIV) but can also arise in HIV-negative patients who have Sjogren's syndrome, Mikulicz's disease, and myoepithelial sialadenitis. Multiple bilateral lymphoepithelial cysts of the major salivary glands, especially the parotid glands, should make one suspect HIV (Varnholt).
Histologically, they are characterized by epithelial-lined cysts with a very dense lymphoid stroma. The cyst wall is often undulating due to projecting nodules of lymphoid tissue. The lining cells can be cuboidal, columnar, respiratory-type, or more commonly, stratified squamous epithelium (Fletcher). It is my impression that they can resemble a Warthin tumor.
It is thought that these cysts arise from salivary inclusions in an intraparotid lymph node. Of interest, lymphoepithelial cysts that are not associated with HIV are usually solitary and unilateral, whereas those associated with HIV are often bilateral with multiple cysts (Fletcher).
Cysts can be as small as 0.5 cm or up to 5 cm in size. Patients present with bilateral parotid gland painless swelling (in HIV associated cases).
Treatments have included observation and/or surgical enucleation. Aspiration frequently results in recurrence. Sclerotherapy with doxycycline has met with some success.
Increased risk of lymphoma.
Fletcher CDM, ed. Diagnostic Histopathology of Tumors. 3rd Ed. Philadelphia, PA: Elsevier; 2007: 309.
Varnholt H, Thompson L, Pantanowitz L. Salivary gland lymphoepithelial cysts. Ear Nose Throat J. 2007 May;86(5):265.