Molecular Pathological Diagnosis And Clinical Research On Mucosa-associated Lymphoid Tissue Lymphoma

Objective:Mucosa-associated lymphoid tissue-derived (MALT) lymphoma is the third commonest subset of non-Hodgkin's B-cell lymphoma inferior to diffuse large B-cell lymphoma and follicular lymphoma. Aetiology research has demonstrated MALT lymphoma correlated to chronic inflammatory caused by organism infection or autoimmune disorders. In histology, the neoplastic cells are small lymphocyte-like appearance, lack of typical morphological characteristics and immunohistochemistry marker. Excluded diagnosis is the main method to differentiate it from other small lymphocytic lymphoma. However, the distinction between severe inflammation and early MALT lymphoma is often difficult. Molecular pathological technique can aid in a determining of lymphocyte clonality and genetic abnormalities, including t(11;18)(q21; q21), t(1;14)(p22;q32) and t(14;18)(q32;q21) in MALT lymphoma. The detection can not only help to diagnosis, but also provides the evidences for clinical prognosis and therapy. Thus, we screen a group of MALT lymphoma cases raised in different sites and establish stable technologies of IGH clonal rearrangement and FISH in formalin fixed and paraffin embedded tissue.Method:We selected94MALT lymphomas,4lymphoid tissue reactive proliferation lesions and10severe chronic inflammation cases.The first part:Apply BIOMED-2primer sets to detect the IGH gene clonal rearrangement of58cases, including44MALT lymphoma originated from different organs,10severe chronic inflammation and4lymphoid tissue reactive proliferation lesions, and evaluate the value oft his protocol in MALT lymphoma diagnosis and differentiated diagnosis. The second part:FISH were performed on FFPET for detection chromosome translocation t(11;18)(q21;q21) and t(14;18)(q32;q21) of MALT lymphoma. The expressed patterns of MALT1and BCL10protein in MALT lymphoma cell were observed by immunohistochemisty, and analyzed the relationship between the patterns and specific chromosome translocation. Combining the medical history and follow-up data, we summarize the clinico-pathological characteristic and prognostic factors.Result:1. Amplification of58selected samples were performed by quality control gene primer set.37of58cases can be used as DNA template (comprising23MALT lymphomas cases,4lymphoid tissue reactive proliferation lesions cases and10severe gastritis cases). Eighteen of23MALT lymphomas and two reactive proliferation lesions specimens were detected monoclonal rearrangement, but10severe gastritis and2reactive proliferation lesions were negative for clonal rearrangement. The sensitivity and specificity were78.3%(18/23) and85.7%(12/14) respectively. The detection rates of IGH gene monoclonal rearrangement by using VH-FR1,VH-FR2and VH-FR3primer multiplex tubes is higher than using one tube or two tubes only (P<0.05)2.45formalin fixed and paraffin embedded tissue samples for fluorescence in situ hybridization has achieved strong signals. MALT1gene split signals were detected in6MALT lymphoma cases(3stomach and3lung), the incidence rate was14.6%(6/41).Three was positive for API2-MALT1(14.3%,3/21). Five cases were positive for trisomy18, comprised4intestine and1ocular adnexa. One primary site of thyroid case were detected amplification of chromosome region where IGH and MALT1gene was located. The break-apart IGH signals were detected in one case primary thyroid and one breast. There was no t (14;18)(q32;q21) abnormality in all cases.3.92MALT lymphomas were directly used for immunostaining to evaluate MALT1and BCL10protein expression. Eighteen cases showed strong MALT1cytoplasmic expression,29cases were moderate cytoplasmic expression and46cases (50.0%) were weak or negative. In all40cases (43.5%) exhibited BCL10expression in both nucleus and cytoplasm,32cases expression in nucleus and15cases expression in cytoplasm only. Other five cases were negative for BCL10staining. The expression of MALTL1in abnormal chromosome group is higher than the normal group, there is statistical significance was found between the two groups(P<0.05). However, no statistical significance was found between the two groups about BCL10expression pattern(P>0.05).4.87MALT lymphomas with full clinical follow-up data were classified four stages according Ann-Arbor staging system. Of all the cases,57cases were stage1,18cases stage â…¡,1cases stage â…¢ and11cases stageâ…£. The5-year survival rates of stage â…  and â…¡ were89.4%and81.4%, the total5-year survival rate of stage â…¡ and â…£ was61.1%. Survival rate has a significant correlation with clinical stage, invasive depth of the wall of gastrointestinal tract, therapeutic measures, organs extra-lymph node involvement and international prognostic index(P<0.05).Conclusion:Based on PCR IGH gene clonal rearrangement test and FISH technique were assistant in MALT lymphoma diagnosis and differentiated diagnosis in FFPET. PCR method is more sensitive than FISH to discriminate early stage MALT lymophma and reactive lesions. Nevertheless, the chromosome aberrant was detected by FISH, which is specific and helpful in diagnosis and therapy. Frequencies of translocation maybe restrict the sensitivity of FISH method. MALT1and BCL10antibody can be used to preliminary screen chromosome translocation.MALT lymphoma is a low-grade B-cell lymphoma with indolent clinical course, the long-term survival of patient with high and the prognosis is good.