BCL2 rearrangement is reported to be an early pathogenetic event in follicular lymphoma (FL) and it is considered as a reliable marker in the follow up of the disease. We aimed to investigate the frequency of BCL2 rearrangement in FLs from northwestern Italy, to evaluate their clinicopathological features, and to investigate alternative genetic aberrations in BCL2-negative FLs.

We collected a series of 76 consecutive FLs diagnosed between 2013 and 2016. All lymphomas underwent histopathological review. Interphasic fluorescent in situ hybridization (FISH) was performed with break apart probes targeting BCL2, IGH, BCL6 and MYC on paraffin embedded (PE) and fresh frozen (FF) specimens. 1p36 region and p53 locus in BLC2-negative cases were investigated using dual color probes. Karyotype analysis was available in a subset of cases.

BCL2 rearrangements were detected in 39 cases (51,3%). Of the remaining 37, 6 showed IGH rearrangement, and were further tested: 1 showed variant BCL2 translocation, 1 had BCL6 rearrangement, and the other 4 were negative for further gene rearrangements. FISH on FF specimens detected small BCL2+ clones in cases otherwise categorized as BCL2-. 1p36 and p53 deletion were observed in 1 and 8 BCL2- FLs, respectively. Karyotype analysis documented 3q, 1p and BCL6 alternative abnormalities in 3 cases.

In conclusion, BCL2 rearrangement is not a constant finding in FL, its frequency being probably affected by geographical factors. Thus, it should not be considered as a reliable molecular marker in the follow up of the disease, unless it is found to be present at the initial diagnosis of FL. Alternative genetic aberrations exist in BCL2-negative cases.

据报道， BCL2重排是滤泡性淋巴瘤 (FL) 的早期发病事件，被认为是疾病随访的可靠标志物。我们的目的是调查意大利西北部 FL 中BCL2重排的频率，评估其临床病理学特征，并研究BCL2阴性 FL 中的替代遗传畸变。

我们收集了 2013 年至 2016 年间连续诊断出的 76 例 FL。所有淋巴瘤均接受了组织病理学检查。在石蜡包埋( PE) 和新鲜冷冻 (FF) 标本上，使用靶向BCL2、IGH、BCL6和MYC的分离探针进行间期荧光原位杂交(FISH)。使用双色探针研究BLC2阴性病例中的1p36 区域和p53基因座。部分病例可进行核型分析。

在 39 例 (51.3%) 中检测到BCL2重排。其余 37 例中，6 例显示IGH重排，并进一步检测：1 例显示变异BCL2易位，1 例有BCL6重排，另外 4 例进一步基因重排呈阴性。FF 标本上的 FISH在其他情况下归类为BCL2 - 的病例中检测到小的BCL2+克隆。分别在 1 个和 8 个BCL2 - FL中观察到1p36 和p53缺失。核型分析记录了3 例3q、1p 和BCL6替代异常。

总之，BCL2重排在 FL 中并不是一个恒定的发现，其频率可能受地理因素的影响。因此，它不应被视为疾病随访中可靠的分子标志物，除非在 FL 的初步诊断中发现它存在。BCL2阴性病例中存在替代遗传畸变。