| Summary: | 碩士 === 國立中興大學 === 生命科學院碩士在職專班 === 89 === The diagnosis of malignant lymphoid neoplasm has been mainly based on histopathologic criteria in which homogeneous-appearing lymphoid cell overgrowths are considered as histologic evidence of clonal expansion and malignancy. Valuable diagnostic information is also provided by immunohistochemical technique. Recently, molecular techniques are increasingly important in the analysis of lymphoid malignancies, both for diagnostic purposes and to accurately evaluate prognosis. PCR has the advantage of high sensitivity, fast turnaround time, and technical simplicity. Furthermore, because small DNA fragments are the targets of PCR, this approach has been successfully applied in the study of formalin-fixed and paraffin-embedded tissue samples. Even in severely damaged archival material, PCR can still detect fragments smaller than 200 bp and identify clonal Ig gene products.
A retrospective study of PCR analysis in 19 cases of lymphoma from pathologic archives of Taichung Veterans General Hospital was performed. There 19 patients were chosen on the basis of that they all have biopsies diagnosed as reactive lymphoid hyperplasia on prior to the final diagnosis of lymphoma.
Total 38 sets of paraffin-embedded tissue samples was submitted to histopathologic study, immunohistochemical study and detect of Ig heavy chain (IgH) by PCR. We found that the diagnostic value of morphologic and immunohistochemical analysis is limited due to the tiny fragments of specimen. With the help of genetic analysis, the diagnostic accuracy could be increased. A clonal amplification pattern was seen in 63% of the cases (12/19) of reactive lymphoid hyperplasia with the FR2A-based system, in 84% of the case (16/19) of malignant lymphoma with the FR2A-based system, in 42% of the cases (8/19) of reactive lymphoid hyperplasia with the FR3A-based system and in 53% of the case (10/19) of malignant lymphoma with the FR3A-based system. Among the 19 patients, 5 biopsies were done more than one year prior to the final diagnosis of malignant lymphoma. In this study we evaluated a panel of PCR-based gene rearrangement studies in a series of lymphoid infiltration related to the differential diagnosis between lymphoid hyperplasia and malignant lymphoma. We show that we can early detect the gene rearrangement early before the histopathologic morphologic changes of lymphoid tissue. Therefore, we conclude that gene rearrangement can reliably done on paraffin-embedded tissue, and they are of great help in early pathologic diagnosis of lymphoma.
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