B-CELL MONOCLONALITY, EPSTEIN-BARR-VIRUS, AND T(14-18) IN MYOEPITHELIAL SIALADENITIS AND LOW-GRADE B-CELL MALT LYMPHOMA OF THE PAROTID-GLAND

Low-grade mucosa-associated lymphoid tissue (MALT) type B-cell lymphom as of the salivary gland arise in a background of myoepithelial sialad enitis (MESA), usually in association with Sjogren's syndrome. The dis tinction between benign MESA and early lymphoma has proved difficult u sing histological criteria alone and the significance of B-cell monocl onality in this respect is controversial. We have used immunohistochem istry and polymerase chain reaction (PCR) amplification of immunoglobu lin heavy-chain VDJ regions to assess clonality in biopsies from 45 pa tients with lymphoid infiltration of the parotid. Sequential biopsies spanning 3-18 years were available from seven patients, three of whom had developed disseminated nodal B-cell lymphoma. In light of previous studies, each biopsy was additionally analyzed for the presence of t( 14;18) and Epstein Barr Virus (EBV) DNA using PCR. Monoclonality was d etected in 34/45 Eases. Comparison of histology with clonality confirm ed earlier suggestions that the emergence of an identifiable populatio n of centrocyte-like B cells around ducts or epithelial islands correl ated with monoclonality. In six of seven patients with sequential biop sies PCR fragments of identical size were amplified from each biopsy, suggesting that demonstrable monoclonality in ''lymphoepithelial'' lym phoproliferative lesions of the salivary gland is indicative of lympho ma. No t(14;18) chromosome translocations were identified; EBV sequenc es were detected in three of 45 cases.