Metanephric adenoma (MA) is a rare benign renal neoplasm. On occasion, MA can be difficult to differentiate from renal malignancies such as papillary renal cell carcinoma in adults and Wilms̕ tumor in children. Despite recent advancements in tumor genomics, there is limited data available regarding the genetic alterations characteristic of MA. The purpose of this study is to determine the frequency of metanephric adenoma cases exhibiting cytogenetic aberration t (9;15)(p24;q24), and to investigate the association between t (9,15) and BRAF mutation in metanephric adenoma. This study was conducted on 28 archival formalin fixed paraffin-embedded (FFPE) specimens from patients with pathologically confirmed MA. Tissue blocks were selected for BRAF sequencing and fluorescent in situ hybridization (FISH) analysis for chromosomal rearrangement between KANK1 on chromosome 9 (9p24.3) and NTRK3 on chromosome 15 (15q25.3), which was previously characterized and described in two MA cases. BRAFV600E mutation was identified in 62% of our cases, 9 (38%) cases were BRAFWT, and 4 cases were uninformative. Of the 20 tumors with FISH results, two (10%) were positive for KANK1-NTRK3 fusion. Both cases were BRAFWT suggesting mutual exclusivity of BRAFV600E and KANK1-NTRK3 fusion, the first such observation in the literature. Our data shows that BRAF mutation in MA may not be as frequent as suggested in the literature and KANK-NTRK3 fusions may account for a subset of BRAFWT cases in younger patients. FISH analysis for KANK1-NTRK3 fusion or conventional cytogenetic analysis may be warranted to establish the diagnosis of MA in morphologically and immunohistochemically ambiguous MA cases lacking BRAF mutations.

中文翻译：

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KANK1-NTRK3融合定义了BRAF突变阴性肾后肾腺瘤的子集

后肾腺瘤（MA）是一种罕见的良性肾肿瘤。有时，MA可能很难与肾恶性肿瘤（例如成人的乳头状肾细胞癌和儿童的Wilms肿瘤）区分开。尽管最近在肿瘤基因组学方面取得了进步，但是关于MA的遗传改变特征的可用数据有限。本研究的目的是确定表现出细胞遗传学异常的后肾腺瘤病例的频率t（9; 15）（p24; q24），并探讨t（9,15）与BRAF突变在后肾腺瘤中的相关性。这项研究是从28例经病理证实的MA的福尔马林固定石蜡包埋（FFPE）标本中进行的。选择组织块进行BRAF测序和荧光原位杂交（FISH）分析，以检测9号染色体上的KANK1（9p24.3）和15号染色体上的NTRK3（15q25.3）之间的染色体重排，先前已在两个MA病例中进行了描述和描述。在我们的病例中，有62％确诊为BRAFV600E突变，其中9例（38％）为BRAFWT，4例无资料。在有FISH结果的20个肿瘤中，有2个（10％）的KANK1-NTRK3融合阳性。这两个案例均为BRAFWT，表明BRAFV600E和KANK1-NTRK3融合体互斥，这在文献中是首次观察到。我们的数据表明，MA中的BRAF突变可能不如文献中所提示的那么频繁，而KANK-NTRK3融合可能是年轻患者中BRAFWT病例的一部分。