Bilateral mucosa-associated lymphoid tissue lymphomas of parotid glands: a 13-year interval.

Benign lymphoepithelial lesions of salivary gland may have a population of monoclonal B cells. There is controversy regarding the clinical significance of monoclonality in these lesions. Morphologically and clinically, benign lymphoepithelial lesions of the salivary gland with monoclonal B cells falls within the spectrum of low-grade B-cell lymphomas of mucosa-associated lymphoid tissue. We report a case of bilateral parotid lymphomas of mucosa-associated lymphoid tissue, separated diagnostically by a 13-year interval. Polymerase chain reaction analysis detected similar clones in the bilateral parotid glands. This finding supports the natural history of mucosa-associated lymphoid tissue lymphomas. In addition, because mucosa-associated lymphoid tissue lymphomas have an unpredictable period of localized disease, recognition of monoclonality in benign lymphoepithelial lesions of salivary glands is important for local cure and can be aided by combining histologic with immunohistochemical, flow cytometric immunophenotyping, and Southern blot and/or polymerase chain reaction analysis.