B-cell monoclonality in salivary lymphoepithelial lesions

Abstract

It is well recognised that lymphoma may arise in a lymphoepithelial lesion of the salivary glands. Although the histological features of this lesion are well described, it is not clear what proportion contain monoclonal populations of lymphocytes at outset. In this study, 22 routinely processed lymphoepithelial lesions in parotid glands were examined for B-cell monoclonality using the polymerase chain reaction (PCR) to amplify the immunoglobulin heavy chain gene and using in situ hybridisation or immunohistochemistry to detect k or λ light chain restriction. B-cell monoclonality was identified in $\text{17}\text{22}$ (77.3%) cases using a combination of the three methods. The detection rate for B-cell monoclonality was highest using PCR with $\text{15}\text{22}$ (68%) cases containing monoclonal immunoglobulin heavy chain gene rearrangements. In a proportion of cases the results of in situ hybridisation and immunohistochemistry were judged to be inadequate and this was probably a reflection of variations in fixation. In 7 patients, sequential biopsies were available from other sites and 6 of these also showed B-cell monoclonality. The results confirm the high prevalence of B-cell monoclonality in lymphoepithelial lesions of the major salivary glands. Furthermore, these results would suggest that PCR is a more reliable technique to identify B-cell monoclonality in routinely processed lymphoepithelial lesions compared to in situ hybridisation and immunohistochemistry.