腺样囊性癌（ACC）是最常见的原发性唾液腺恶性肿瘤之一。在唾液腺肿瘤中，ACC有多个良性和恶性伪装者。准确诊断ACC对患者的最佳管理和随访至关重要。85-90％的ACC中已描述了MYB的升高，但在其他唾液腺肿瘤中没有。在ACC中，MYB的升高可能是由于遗传重排t（6;9）（q22-23；p23-24）、MYB拷贝数变异（CNV）或增强子劫持的结果。MYB升高的所有机制均导致RNA转录增加，可使用RNA原位杂交（ISH）方法检测到。在本研究中，使用包括78个ACC在内的138个原发性唾液腺肿瘤，评估MYB RNA ISH的诊断实用性，以区分具有突出的筛形结构的其他原发性唾液腺肿瘤，包括多形腺瘤、基底细胞腺瘤、基底细胞腺癌、上皮肌上皮癌和多形性腺癌。还进行了荧光原位杂交和下一代测序以评估RNA ISH对检测MYB基因改变时MYB RNA升高的灵敏度和特异度。MYB RNA的检测对于诊断唾液腺肿瘤中的ACC具有92.3％的敏感性和98.2％的特异性。与FISH MYB折断探针的（42％）ACC比较，ISH检测MYB RNA的灵敏度（92.3％）明显更高。下一代测序未显示MYB改变的情况缺乏MYB RNA过度表达，表明MYB RNA ISH对于检测MYB基因改变具有很高的灵敏度。虽然不完全排除了现代样本与老年回顾性组织样本中RNA降解的灵敏度可能更高的可能性，但除了高灵敏度和特异性之外，MYB RNA检测还可以使用标准的IHC平台和协议进行，并可以使用亮场显微镜进行评估，使其成为日常临床实践中的时间和成本效益的诊断工具。 Copyright © 2023 Royal College of Pathologists of Australasia。Elsevier B.V.保留所有权利。

Adenoid cystic carcinoma (ACC) is one of the most common primary salivary gland cancers. ACC has several benign and malignant mimics amongst salivary gland neoplasms. An accurate diagnosis of ACC is essential for optimal management of the patients and their follow-up. Upregulation of MYB has been described in 85-90% of ACC, but not in other salivary gland neoplasms. In ACC, MYB upregulation can occur as a result of a genetic rearrangement t(6;9) (q22-23;p23-24), MYB copy number variation (CNV), or enhancer hijacking of MYB. All mechanisms of MYB upregulation result in increased RNA transcription that can be detected using RNA in situ hybridisation (ISH) methods. In this study, utilising 138 primary salivary gland neoplasms including 78 ACC, we evaluate the diagnostic utility of MYB RNA ISH for distinguishing ACC from other primary salivary gland neoplasms with a prominent cribriform architecture including pleomorphic adenoma, basal cell adenoma, basal cell adenocarcinoma, epithelial myoepithelial carcinoma, and polymorphous adenocarcinoma. Fluorescent in situ hybridisation and next generation sequencing were also performed to evaluate the sensitivity and specificity of RNA ISH for detecting increased MYB RNA when MYB gene alterations were present. Detection of MYB RNA has 92.3% sensitivity and 98.2% specificity for a diagnosis of ACC amongst salivary gland neoplasms. The sensitivity of MYB RNA detection by ISH (92.3%) is significantly higher than that of the FISH MYB break-apart probe (42%) for ACC. Next generation sequencing did not demonstrate MYB alterations in cases that lacked MYB RNA overexpression indicating high sensitivity of MYB RNA ISH for detecting MYB gene alterations. The possibility that the sensitivity may be higher in clinical practice with contemporary samples as compared with older retrospective tissue samples with RNA degradation is not entirely excluded. In addition to the high sensitivity and specificity, MYB RNA testing can be performed using standard IHC platforms and protocols and evaluated using brightfield microscopy making it a time and cost-efficient diagnostic tool in routine clinical practice.Copyright © 2023 Royal College of Pathologists of Australasia. Published by Elsevier B.V. All rights reserved.