Detection of clonal B cell populations in paraffin-embedded tissues of primary gastric and thyroidal B-cell lymphoma using the polymerase chain reaction.

Nine cases of primary gastric B-cell lymphoma (PGL) and ten cases of primary thyroidal B-cell lymphoma (PTL) were investigated to detect monoclonality of immunogloblin heavy chain (IgH) gene by polymerase chain reaction (PCR). Monoclonal bands could be detected in 5 of 9 cases of PGL and in 8 of 10 cases of PTL using paraffin sections. One case gave polyclonal bands. In this case, large numbers of small lymphocytes were found to infiltrate the tumor. Sequencing of the PCR products in a part of these cases showed the dominant expression of a single rearrangement in monoclonal cases, whereas in polyclonal cases specific single rearrangements were not found. Interestingly, the dominant clone had the same CDR3 region in cases 4 and 6 of PGL. It was suggested that the some specific antigens might participate in oncogenesis of PGL. The application of the method used in the present study may be helpful in routine diagnosis and in pathological research of B-cell lymphomas.