A fluorescence in situ hybridization study of ETV6-NTRK3 fusion gene in secretory breast carcinoma

The translocation t(12;15)(p13;q25), in which the ETV6 gene from chromosome 12 is rearranged with the NTRK3 gene from chromosome 15, has recently been identified in secretory breast carcinoma (SBC). This fusion gene was initially described in congenital fibrosarcoma and congenital mesoblastic nephroma. The biological consequence of this translocation is the expression of a chimeric protein tyrosine kinase with potent transforming activity. To assess the frequency of t(12;15)(p13;q25) in breast cancer, we developed complementary probe sets (fusion and split-apart probes) for the detection of this translocation by fluorescence in situ hybridization (FISH) in paraffin-embedded, formalin-fixed tissue sections. We tested four histologically confirmed cases of SBC for the presence of the ETV6-NTRK3 gene fusion and then applied the FISH assay to tissue microarrays (TMAs) in order to screen 481 cases of formalin-fixed, paraffin-embedded invasive breast carcinomas of various histologic subtypes. Three of the four cases of SBC revealed fusion signals. Of the 481 cases in the TMAs, 202 gave signals of sufficient quality for screening by FISH, and only one case showed fusion signals in most or all of the tumor cells. On review of the histology of this case, SBC was confirmed. On the other hand, none of the fusion-negative breast cancers revealed SBC histology. In all cases, the results from the fusion and split-apart FISH assays for the ETV6-NTRK3 fusion genes were concordant. Our data suggest that the ETV6-NTRK3 fusion gene is a specific genetic alteration in SBC.     

滑膜肉瘤融合基因SYT-SSX的检测及意义分析

目的研究逆转录-聚合酶链反应(RT-PCR)在滑膜肉瘤石蜡包埋组织中检测SYT-SSX融合基因的可行性和意义。方法20例滑膜肉瘤标本均用10％福尔马林固定、石蜡包埋。采用RT-PCR检测SYT-SSX融合基因。看家基因PBGD作为内参照。结果所有标本均可检测到PBGDmRNA的表达。18例(90％)检测到融合基因SYT-SSX的表达。SYT-SSX1型占12例(66．7％)，SYT-SSX2型占6例(33．3％)。结论在经福尔马林固定经石蜡包埋组织的滑膜肉瘤用RT-PCR方法检测SYT-SSX融合基因是可行的，有较高的敏感性。融合基因亚型可能为预后提供重要信息。     

滑膜肉瘤石蜡包埋组织SYT-SSX融合基因检测的临床病理意义

目的：探讨在石蜡包埋组织中检测SYT－SSX融合基因的可行性及其对滑膜肉瘤的诊断,分型和鉴别诊断的价值。方法：收集滑膜肉瘤标本38例,以恶性周围神经鞘膜瘤,纤维肉瘤,平滑肌肉瘤,尤文肉瘤,血管外皮肉瘤和转移性腺癌作为对照,共40例,均为甲醛固定,石蜡包埋组织,用逆转录－聚合酶链反应（RT－PCR）方法检测SYT－SSX融合基因mRNA表达,以看家基因PBGD作为内对照检测mRNA质量。结果：78例标本中64例（占82．1％）可检出PBGD mRNA表达,38例滑膜肉瘤中33例中可检出SYT－SSX融合基因mRNA表达,对照组无一例检出SYT－SSX基因,去除PBGD及SYT－SSX均阴性病例1例,滑膜肉瘤SYT－SSX融合基因检出率为89．2％（33／37）,33例SYT－SSX阳性滑膜肉中,SYT－SSX1型22例,SYT－SSX2型6例,5例无法区分。融合基因类型与滑膜肉瘤组织学类型有关。10例双相型滑膜肉瘤均为SYT－SSX1型,而18例单相型滑膜肉瘤中SYT－SSX1型12例,SYT－SSX2型6例,二者差异有统计学意义（P＜0．05）,结论：（1）从石蜡包埋组织中检测SYT－SSX融合基因对滑膜肉瘤有较高的敏感性和特异性,可用于滑膜肉瘤的诊断和鉴别诊断;（2）SYT－SSX融合基因类型与滑膜肉瘤组织学类型相关,SYT－SSX2型仅见于单相型。     

黏液样/圆细胞型脂肪肉瘤石蜡包埋组织中FUS-CHOP融合基因检测的临床病理学意义

目的 探讨在甲醛固定、石蜡包埋组织中检测FUS-CHOP融合基因的可行性及其对黏液样／圆细胞型脂肪肉瘤的诊断和鉴别诊断的价值。方法 收集黏液样／圆细胞型脂肪肉瘤档案标本44例,以非典型性／分化良好型脂肪肉瘤、多形性脂肪肉瘤、低度恶性黏液纤维肉瘤／黏液样恶性纤维组织细胞瘤等作为阴性对照,共60例。所有标本均为甲醛固定、石蜡包埋组织。用嵌套式逆转录-聚合酶链反应(RT-PCR)方法检测FUS-CHOP融合基因mRNA表达并经测序证实,以看家基因PGK作为内对照检测mRNA质量。结果 104例肿瘤标本中,93例(89．4％)可检出PGK mRNA表达,其中黏液样／圆细胞型脂肪肉瘤标本PGK阳性39例(88．6％),对照组PGK阳性54例(90％)。44例黏液样／圆细胞型脂肪肉瘤中20例可检出Ⅱ型FUS-CHOP融合基因表达,未能检测到Ⅰ型FUS-CHOP融合基因表达,排除内对照阴性病例5例,阳性率为51．3％(20／39)。对照组60例肿瘤标本均未检出FUS-CHOP融合基因表达。结论 (1)嵌套式RT-PCR方法检测FUS-CHOP mRNA表达可用于甲醛固定、石蜡包埋组织。(2)FUS-CHOP是黏液样／圆细胞型脂肪肉瘤的特异性分子遗传学标志物。采用嵌套式RT-PCR方法检测FUS-CHOP敏感性较高,特异性强,可用于该肿瘤的诊断和鉴别诊断。     

ETV6 rearrangements in patients with infantile fibrosarcomas and congenital mesoblastic nephromas by fluorescence in situ hybridization.

Congenital mesoblastic nephroma (CMN) and infantile fibrosarcoma (IFS) are two pediatric tumors arising in the kidneys and soft tissues of infants, respectively. Recently, a t(12;15)(p13;q25) resulting in ETV6-NTRK3 gene fusion was detected in patients with IFS and in patients with the cellular type of CMN, suggesting a common pathogenetic pathway. We investigated the presence or absence of ETV6 rearrangements and numerical abnormalities of chromosome 11 by using fluorescence in situ hybridization on paraffin-embedded material from five cases of IFS, two of CMN, and one of mixed type (CMN and IFS) found in our files. In three cases of IFS, we found ETV6 gene rearrangement but a normal copy number of chromosome 11. One case each of IFS, the cellular type of CMN, and the mixed type (CMN and IFS) had both abnormalities. In a case of classic CMN, neither trisomy 11 nor gene rearrangement was found. It is possible that trisomy 11 is a later, nonessential event in the pathogenetic process or that this secondary aberration is associated with still-unrecognized clinical or biological characteristics. We confirmed that IFS and the cellular type of CMN are cytogenetically related and can occur synchronously in the same organ.     

Secretory carcinoma of the sinonasal cavity and pharynx: A retrospective analysis of four cases and literature review

Secretory carcinoma (SC) is a recently recognized type of salivary gland tumor characterized by t(12;15) (p13;q25) translocation resulting in an ETV6-NTRK3 gene fusion. Most SCs are located in a main salivary gland, and primary sinonasal secretary carcinoma is rare. We describe three cases of primary SC in the sinonasal cavity with high-grade transformation (HGT) in one case, and the first case in the pharynx. All tumors comprised slightly atypical cells with solid, tubular, microcystic growth patterns. The case with HGT included two components with distinct sharp boundaries and comedo necrosis, high mitotic figures and obvious cellular atypia. Tumor cells were positive for vimentin, S100, and Gata-3 and negative for p63 and DOG-1. Three cases showed nuclear staining of pan-TRK and one showed cytoplasmic staining. All cases harbored ETV6 gene rearrangement, and ETV6-NTRK3 gene fusion was detected in three cases. Most patients were treated with radical resection and adjuvant therapy. After excision, all remained tumor-free for 65–164 months (medium 98.5 months). SC in the sinonasal cavity and pharynx is a low-grade malignant tumor with histologic features overlapping those of other salivary gland tumors. Immunohistochemical analysis and fluorescence in situ hybridization are useful techniques for its differential diagnosis.