B淋巴细胞增生性疑难病例中IgH基因克隆性重排的分析

Immunoglobulin heavy chain gene rearrangement study in difficult cases of B-cell lymphoproliferative disorder

目的探讨IgH基因克隆性重排对B淋巴细胞增生性疑难病变的辅助诊断价值。方法检测77例B淋巴细胞增生性疑难病例中IgH基因的克隆性重排情况，均采用BIOMED-2系统IgH克隆性试剂盒中FR1、FR2、FR3三组家族引物进行PCR及聚丙烯酰胺凝胶电泳，硝酸银染色后观察，并对照最终病理诊断进行分析。结果77例病变的最终病理诊断：B淋巴细胞反应性增生12例，不能排除B淋巴细胞不典型增生或淋巴瘤20例，B细胞性淋巴瘤45例。三组中FR1、FR2和FR3至少有一个为阳性的比值分别为2／12、11／20（55％）和36／45（80％）。B细胞性淋巴瘤中，FR1、FR2和FR3的阳性率分别为60％（27／45）、60％（27／45）、56％（25／45），其类型有边缘区B细胞性淋巴瘤20例（其中黏膜相关淋巴组织型结外边缘区淋巴瘤18例，结内边缘区淋巴瘤2例），弥漫性大B细胞淋巴瘤7例，滤泡性淋巴瘤7例，套细胞性淋巴瘤1例，Burkitt淋巴瘤1例，浆细胞瘤4例，不能分型5例。FR1、FR2和FR3三者检测均为阴性但仍诊断为淋巴瘤9例（20％），其中1例后来出现肝脏B细胞淋巴瘤。对IgH基因重排阳性的B淋巴细胞反应性增生和不典型增生14例的随访结果，4例重新取活检后诊断为B细胞性淋巴瘤，其中3例IgH基因重排检测为阳性。结论联合检测IgH基因FR1、FR2和FR3克隆性重排对B淋巴细胞增生性疑难病变诊断有重要的辅助价值；对形态改变和免疫表型诊断淋巴瘤依据不足而基因重排阳性者，重取活检或随访有一定价值；对阴性病例有必要补充IgH基因重排及IgK和IgL基因重排的检测以提高检测敏感性。

Objective To evaluate the ancillary diagnostic value of IgH gene rearrangements in those B-ceB lymphoproliferative disorder cases whom are difficult in making a final diagnosis. Methods IgH gene clonal rearrangements were retrospectively analyzed in a total of 77 diagnostically difficult B-cell lympho-proliferative patients. Standardized BIOMED-2 system IgH gene clonality assay kit targeting FR1, FR2, FR3 was used, followed by heteroduplex-polyaerylamide gel eleetrophoresis （PAGE） and silver nitrate staining. Results The final diagnoses of the 77 cases were： 12 cases of reactive lymphoid hyperplasia, 20 cases of atypical lymphoid hyperplasia or suspicious lymphoma, and 45 cases of B-cell lymphoma. Detection rates of at least one positive reaction were 2/12, 11/20 （55%）, 36/45 （80%）in the three groups, respectively. In B-cell lymphomas, the clonality detection rate of FRI, FR2 and FR3 was 60% （ 27/45 ）, 60% （27/45） and 56% （ 25/45 ）, respectively. The type distribution were ： 20 marginal zone lymphomas, including 18 extranodal marginal zone B-cell lymphoma of mueosa-associated lymphoid tissue, 7 diffuse large B-cell lymphomas, 7 follicular lymphomas, 1 mantle-cell lymphoma, 1 Burkitt＇s lymphoma, 4 plasma cell neoplasms and 5 unclassified B-cell lymphomas. Rearrangements of FR1, FR2 or FR3 were not detected in 9 （20%） of the B cell lymphoma cases, nevertheless, one of them had developed liver lesion later, and was confirmed finally to be B cell lymphoma. Fourteen patients of reactive lymphoid hyperplasia with positive IgH gene clonal rearrangements, and atypical lymphoid hyperplasia had follow-up history available. Four of them were diagnosed as lymphoid malignancies upon further biopsy, and in three of them, clonal IgH gene rearrangements were detected. Conclusions B-cell lymphoproliferative disorder requiring a detection of clonal IgH gene rearrangement for making a final diagnosis. Combined detections of three IgH FR1, FR2 and FR3 rearrangements provide important ancillary diagnostic value in confirming suspected B-cell lymphoproliferative disorders. It is important to take an additional biopsy or to follow-up those patients who that have a detectable IgH gene clonal rearrangement but without apparent morphological evidence of lymphoma. For cases with a negative IgH gene rearrangements, it might be necessary to perform clonality analysis for other forms of gene rearrangements including IgH or IgK and IgL in order to further improve the detection sensitivity.