ANALYSIS OF IMMUNOGLOBULIN HEAVY-CHAIN GENE REARRANGEMENT IN MYOEPITHELIAL SIALADENITIS BY POLYMERASE CHAIN-REACTION

Myoepithelial sialadenitis (MESA) can often be difficult to distinguis h from low grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT). The authors have previously studied a series of 25 patients wi th MESA and identified histologic and immunologic features predictive of extrasalivary lymphoma (ESL), The authors have now analyzed formali n-fixed, paraffin-embedded salivary gland tissue from 21 of these pati ents (and 1 new patient) for immunoglobulin heavy chain (IgH) gene rea rrangement by a semi-nested polymerase chain reaction (PCR) technique to compare monoclonality by IgH PCR with clinical outcome (median foll ow-up 6.7 Sears, range 3 months-19.4 years) and the paraffin section i mmunophenotype. The PCR technique employed consensus primers from vari able (FR3A) and joining regions (LJH, VLJH) of the IgH gene. A monoclo nal PCR product was detected in 16 of 28 specimens from 13 of 22 patie nts, By Fisher's exact test, a monoclonal PCR pattern did not correlat e (P > .05) with development of ESL, broad strands of monocytoid B-cel ls, plasma cell light chain restriction by immunoperoxidase, or CD43 c oexpression on monocytoid B cells by immunoperoxidase. This study sugg ests that the majority of MESA lesions harbor monoclonal B-cell popula tions and that clonality does not predict progression to clinically ov ert lymphoma, Acquired salivary gland MALT, in the form of MESA, may p rogress to a process that is clonal but not necessarily malignant. Ext ranodal lymphoma develops in a minority of patients with this lesion.