IgM在滤泡性淋巴瘤中的表达模式研究

目的探讨IgM在滤泡性淋巴瘤(FL)中的表达模式,为FL和淋巴滤泡反应性增生(RFH)的鉴别诊断提供新的辅助性依据。方法对25例RFH和40例FL行IgM免疫组化染色,并对照分析。结果 25例RFH病例均显示IgM可勾勒出生发中心的滤泡树突细胞(FDCs)网,生发中心B细胞阴性或偶尔有很弱的阳性。IgM在FL的肿瘤性滤泡中有3种表达模式:模式1(28例)显示瘤细胞弥漫表达IgM,但是没有IgM阳性的FDC网;模式2(7例)显示肿瘤性滤泡中的瘤细胞和FDC网均IgM阴性;模式3(5例)显示瘤细胞可以表达IgM(3例)或不表达(2例),共同的特点是FDC网部分保留了IgM的表达。这5例在形态学上显示肿瘤性滤泡周围有保存较好的套细胞区。结论免疫组化显示肿瘤性滤泡中FDC网对IgM的表达完全消失或显著减少,以及B细胞对IgM表达的明显上调,是FL区别于RFH的显著特点。

Analysis of IgM staining pattern in follicular lymphoma

Objective To explore the IgM staining pattern in follicular lymphoma（ FL）. Methods Twenty-five cases of reactive follicular hyperplasis（ RFH） and 40 cases of FL specimens were analyzed by light microscopy and immunohistochemistry. Results In RFH,IgM highlighted processes of follicular dendritic cells（ FDCs）,with occasional very dim staining of germinal center B cells. In FL,IgM expression patterns were of three types. Pattern I（ 28 cases） stained tumor cells within neoplastic follicles,with no staining of FDCs. Pattern II（ 7 cases） stained neither tumor cells nor FDCs. Pattern III（ 5 cases） stained tumor cells with（ 3 cases） or without（ 2 cases） IgM expression; however,variable and attenuated IgM expression was observed on FDCs in each case. Interestingly,significant numbers of mantle cells were preserved around the neoplastic follicles in these 5 cases. Conclusion The data suggest that a complete or considerable loss of IgM expression on FDCs is a typical feature of FL; moreover,increased IgM expression by B cells can also serve as an indicator of immunophenotypic abnormality in FL.