High prevalence of B-cell monoclonality in labial gland biopsies of Japanese Sjögren's syndrome patients.

Patients with Sjögren's syndrome (SS) have an increased risk of developing malignant lymphoma. Although some clinical parameters may herald the imminent onset of lymphoma, few reliable markers are available to predict the progression to a malignant lymphoproliferative disorder. Although there are a number of immunological and serologic features that distinguish SS in Japanese patients, in common with their Western counterparts these patients also have an increased risk of lymphoid neoplasia. Recently we have reported finding a high prevalence (17%) of monoclonal immunoglobulin (Ig) heavy chain gene rearrangements in labial salivary gland (LSG) biopsies of Western SS using the polymerase chain reaction (PCR). In many cases this finding was predictive for the subsequent development of lymphoma. In this study LSG from 50 Japanese SS patients were examined for Ig heavy chain gene monoclonality using PCR to amplify the VDJ region and identified in 7 of 50 (14%) cases. Three patients with monoclonality in the LSG had evidence of lymphoma at extra-salivary gland sites. In one of these the diagnosis of lymphoma was made subsequent to lip biopsy. In the other two lymphoma at extra-salivary gland sites was diagnosed prior to LSG biopsy. The results suggest that the prevalence of Ig heavy chain gene monoclonality in LSG of Japanese SS patients is similar to that in the West, and that neoplastic cells can be identified in LSG as a component of more widely disseminated disease.