B-CELL MONOCLONALITY IN SALIVARY LYMPHOEPITHELIAL LESIONS

It is well recognised that lymphoma may arise in a lymphoepithelial le sion of the salivary glands. Although the histological features of thi s lesion are well described, it is not clear what proportion contain m onoclonal populations of lymphocytes at outset. In this study, 22 rout inely processed lymphoepithelial lesions in parotid glands were examin ed for B-cell monoclonality using the polymerase chain reaction (PCR) to amplify the immunoglobulin heavy chain gene and using in situ hybri disation or immunohistochemistry to detect kappa or lambda, light chai n restriction. B-cell monoclonality was identified in 17/22 (77.3%) ca ses using a combination of the three methods. The detection rate for B -cell monoclonality was highest using PCR with 15/22 (68%) cases conta ining monoclonal immunoglobulin heavy chain gene rearrangements. In a proportion of cases the results of in situ hybridisation and immunohis tochemistry were judged to be inadequate and this was probably a refle ction of variations in fixation. In 7 patients, sequential biopsies we re available from other sites and 6 of these also showed B-cell monocl onality. The results confirm the high prevalence of B-cell monoclonali ty in lymphoepithelial lesions of the major salivary glands. Furthermo re, these results would suggest that PCR is a more reliable technique to identify B-cell monoclonality in routinely processed lymphoepitheli al lesions compared to in situ hybridisation and immunohistochemistry.