Lymphoid infiltrates of the salivary glands: pathology, biology and clinical significance.

Lymphoid infiltrates of the salivary glands are common to a variety of pathologic conditions including autoimmune disorders, malignant lymphomas, and immunoregulatory responses to parenchymal neoplasms. Clearly, the correct identification of these salivary gland lymphoid infiltrates has important implications regarding patient prognosis and management. Immunophenotypic and molecular analyses have demonstrated that many lesions formerly regarded as myoepithelial sialadentis or benign lymphoepithelial lesion in fact represent neoplastic lymphoid proliferations with the potential for extrasalivary dissemination. In the most recent classification scheme of non-Hodgkin's lymphomas, these neoplasms fall within the spectrum of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue. In the early stages of HIV infection, patients may develop salivary gland enlargement resulting from cystic lymphoepithelial lesions. These lesions are thought to reflect a localized manifestation of persistent generalized lymphadenopathy. Although HIV-associated salivary gland disease is regarded as a benign condition, malignant lymphoma has been described in association with some of these lesions, and further work is required to define more precisely the risk of salivary gland lymphoma in HIV-infected patients. Tumor-associated lymphoid proliferation refers to a prominent lymphoid reaction accompanying certain epithelial tumors of the salivary glands. Although tumor-associated lymphoid proliferation has not received as much attention as other types of salivary lymphoid infiltrates, it is a common phenomenon that is sometimes mistaken for an intraparotid lymph node harboring metastatic carcinoma.