Lymphoma is a malignant tumor that occurs in lymphoid tissue. Lymphatic tissue consists of T and B lymphocytes, histiocytes and other immunologically active cells. Because of its special histological structure, when it is stimulated by antigen, it can produce different degrees of reactive hyperplasia, disturbance of the normal structure of lymph nodes, proliferation of immunoblasts, increased nuclear division phase, and other pseudo-malignant images. Therefore, it is sometimes difficult to determine its benign or malignant nature based on morphological observation alone. At present, about 70% of lymphoid tissue proliferative diseases in general pathology can be clearly diagnosed with conventional sections in about 25% of cases. However, nothing can be done for early immature cells without surface markers, or abnormal cells that have lost their surface markers. In cases with a high reactive proliferative cell component, the tumor cells may be masked even if they have an immunophenotype. Conversely, false positives may also result from antigen spread due to manipulation, etc. The clonal gene rearrangement assay technique developed in recent years offers the possibility to determine the diagnosis in difficult, early or microscopic specimens and is an important complement to morphological examination and immunohistochemical methods. A class of glycoproteins consisting of multiple subunits that have the ability to bind specifically to antibodies or antigens on the surface of lymphocytes includes IgH and IgL produced by B lymphocytes and TCR (T cell receptor) produced by T cells. Both have similar genetic codes and are generally composed of variable (V region), variable (D region), junctional (J region) and constant (C region) regions. In the germline state, the division of these regions on the chromosome is discontinuous. The V, D, J and C genes are arranged in a linear pattern from the 5′ end to the 3′ end on a single strand of DNA, with insertion sequences of varying lengths still separating them. When lymphocytes reach a certain stage of development, they are selectively joined together by the action of special recombinases (i.e. gene rearrangement) in order to constitute a functionally expressed gene. Lymphocytes need to undergo several gene rearrangements from maternal cell differentiation to maturity. Since the V, D and J regions all have multiple selectable gene fragments, the freedom of gene rearrangement can be as high as 106 to 107. Individually, each lymphocyte has a specific form of gene rearrangement, i.e. a unique gene coding structure, for the antigen or receptor gene encoding. If a T or B lymphocyte produces a monoclonal proliferation at some stage of the rearrangement, it becomes a lymphoma. This means that the clonal proliferation of lymphoma cells results in a certain quantitative predominance of their specific gene rearrangement form. Thus, it becomes an indicator of the clonality of the cells. This is the theoretical basis of lymphoma genetic diagnosis. Currently, there are two main methods used for lymphoma gene rearrangement analysis. I. Multiplex chain reaction amplification technique (PCR) This method was first designed successfully by Mullis and others in the United States (1985). In 1989, it was reported to be used for lymphoma gene rash. The principle is to select about 20 conserved nucleotide sequences in the V, D, J, and C regions of the IgH and TCR gene codes, synthesize one or more pairs of primers (family genes) artificially, complement the single stranded bases of the template DNA to be tested, and amplify the target DNA sequence fragments. In the case of lymphoma the amplification product appears as a monoclonal single band by electrophoresis. In contrast, benign proliferative lymphoid tissue appears diffusely smear-like and does not form a single band. The literature reports that PCR gene diagnosis of lymphoma has the advantages of being specific, sensitive, rapid, and available for both fresh and paraffin-embedded tissues. However, the only gene that has been successfully detected by PCR is IgH gene. The PCR method for IgH gene rearrangement also has two obvious problems: 1) many influencing factors and poor stability; 2) still more than 10% false negatives and sensitivity needs to be improved. Second, Southern blot hybridization method This method was first reported by Southern, University of Edinburgh, Scotland (1975). The principle is that two single-stranded DNA bases can be combined with synthetic complementary single-stranded DNA probes (generally labeled with isotopes.) The Southern Blot method applied to gene rearrangement detection was first performed by Korsmeyer et al. in 1981. Cellular DNA is extracted and enzymatically cleaved with restriction endonucleases, and characteristic fragments of germline DNA are produced. However, cellular DNA that has undergone gene rearrangement has altered enzymatic sites that produce enzymatic segments of DNA that are distinct from the germline. After transmembrane transfer, hybridization with labeled DNA probes can reveal clonal rearrangement bands if a certain number of clonally proliferating lymphocytes are present (>1-5%). For normal or polyclonal lymphocytic proliferation, diffuse bands are shown due to the varying sizes of rearranged fragments. Southern analysis has been applied to the detection of clonal rearrangements in IgH, Igk, Ig1 and various TCRs, and is considered the “gold standard” for gene rearrangement detection with satisfactory sensitivity and reliability. However, it is only suitable for scientific research but not for clinical diagnosis because of the disadvantages of requiring a large amount (10 mg) of fresh or frozen tissue, complicated operation, long operation time (about two weeks), and the need for over-emission isotope labeling and easy contamination. The fluorescein-labeled IgH, Igk, Ig1 and various TCR probe chemiluminescence kits introduced by DAKO overcome the above-mentioned shortcomings, replacing isotopes with fluorescein as the marker; shortening the exposure time (5~10 minutes), but the sensitivity is not reduced, which is very beneficial to the promotion and application in clinical diagnosis.