RESUMO
Polymerase chain reaction (PCR) for antigen receptor rearrangement is a sensitive technique for detecting lymphocyte-proliferative disorders, but it tends to produce false-positive results, a phenomenon termed pseudoclonality. Heteroduplex analysis, which is useful to distinguish clonal reactions from pseudoclonal ones in dogs, can be applied to avoid misdiagnosis and determine the reliability of results. In the current study, PCR for antigen receptor rearrangement was used to identify clonal proliferation of lymphocytes in duodenal and lymphoid tissue from dogs presenting with chronic vomiting and enlarged peripheral lymph nodes typical of multicentric lymphoma, and the test results were verified with heteroduplex analysis. In the case of almost all of the duodenal samples, even without a histologic diagnosis of lymphoma, a distinct band similar to that observed in the case of lymphoma was obtained for both B- and T-cell clonality. All of the bands obtained from the nonneoplastic duodenum disappeared following heteroduplex analysis of the PCR product, whereas the distinct bands from the lymphoma remained. In the lymph node samples, the pseudoclonal bands that disappeared in the heteroduplex analysis were detected mainly in B cells. In conclusion, heteroduplex analysis with PCR for antigen receptor rearrangement is a suitable tool for diagnosing canine lymphoma and decreasing the possibility of misdiagnosis of pseudoclonality.
