Brown Noah A, Betz Bryan L, Weigelin Helmut C, Elenitoba-Johnson Kojo S J, Lim Megan S, Bailey Nathanael G
From the Department of Pathology, University of Michigan, Ann Arbor.
Am J Clin Pathol. 2015 Jan;143(1):89-99. doi: 10.1309/AJCPDN4Q1JTFGCFC.
Detection of BRAF V600E mutations in hairy cell leukemia (HCL) has important diagnostic utility. In this study, we sought to compare immunohistochemistry with an antibody specific for this mutation to a sensitive molecular assay.
The performance of the BRAF V600E-specific VE1 antibody was compared with that of allele-specific polymerase chain reaction (PCR) in 22 formalin-fixed, paraffin-embedded (FFPE) specimens with HCL involvement, along with nine splenic marginal zone lymphomas (SMZLs), 10 follicular lymphomas (FLs), 10 mantle cell lymphomas (MCLs), and 10 chronic lymphocytic leukemia/small lymphocytic lymphomas (CLL/SLLs). An additional 11 SMZLs, 100 FLs, 20 MCLs, 83 CLL/SLL specimens, and 49 reactive tonsils within tissue microarrays were stained with VE1.
A BRAF V600E mutation was detected in 17 (77.3%) of 22 HCL cases by PCR. Immunohistochemistry demonstrated VE1 staining in 20 (90.9%) cases, identifying low-level (~1%) involvement in three HCL cases that were mutation negative by PCR. Evaluation of additional material from these patients confirmed the presence of BRAF V600E. Thirty-nine non-HCL cases were negative by both methods. Within tissue microarrays, weak false-positive staining was observed in two (0.8%) of 263 non-HCL cases.
VE1 immunohistochemistry is more sensitive than allele-specific PCR in FFPE bone marrow specimens and can be applied to decalcified core biopsy specimens that are not appropriate for molecular techniques.
检测毛细胞白血病（HCL）中的BRAF V600E突变具有重要的诊断价值。在本研究中，我们试图将针对该突变的特异性抗体免疫组化与灵敏的分子检测方法进行比较。
将BRAF V600E特异性VE1抗体的性能与等位基因特异性聚合酶链反应（PCR）在22例有HCL累及的福尔马林固定、石蜡包埋（FFPE）标本中的性能进行比较，同时纳入9例脾边缘区淋巴瘤（SMZL）、10例滤泡性淋巴瘤（FL）、10例套细胞淋巴瘤（MCL）和10例慢性淋巴细胞白血病/小淋巴细胞淋巴瘤（CLL/SLL）。另外，在组织芯片上对11例SMZL、100例FL、20例MCL、83例CLL/SLL标本和49例反应性扁桃体用VE1进行染色。
通过PCR在22例HCL病例中的17例（77.3%）检测到BRAF V600E突变。免疫组化显示20例（90.9%）病例有VE1染色，在3例PCR检测为突变阴性的HCL病例中发现了低水平（约1%）的累及。对这些患者的额外材料进行评估证实了BRAF V600E的存在。39例非HCL病例两种方法检测均为阴性。在组织芯片中，263例非HCL病例中有2例（0.8%）观察到弱阳性染色。
在FFPE骨髓标本中，VE1免疫组化比等位基因特异性PCR更敏感，可应用于不适用于分子技术的脱钙芯针活检标本。
