Abstract：
NUT carcinoma (NC) is a highly aggressive, poorly differentiated carcinoma that harbors a t(15:19) translocation, leading to the fusion of the NUTM1 gene. While the upper aerodigestive tract along the midline (head, neck, thorax, and mediastinum) is commonly reported as the primary site of NC, subsequent cases have emerged in diverse locations. Achieving a definitive diagnosis based solely on morphology is challenging; however, it can be achieved using immunohistochemistry (IHC) specific to the NUT antibody or by demonstrating the characteristic BRD4::NUTM1 fusion. Accurate and timely diagnosis can potentially inform patient management and guide treatment. While histologic documentation of NC is commonly found, there is a limited description of its cytologic features. A 39-year-old male with a history of sinonasal squamous cell carcinoma (SCC) presented with a right parotid mass aspirated via fine needle aspiration cytology (FNA). Histologic examination of the previous sinonasal pathology reviewed at our institution revealed sheets of primitive-appearing, monotonous, undifferentiated cells with distinct, prominent nucleoli. Additionally, there were foci of abrupt keratinization, accompanied by a notable neutrophilic infiltrate. The initial diagnosis of SCC was reclassified to NC and confirmed through NUT IHC and molecular testing. Although the parotid FNA initially suggested the possibility of a variety of small round blue cell tumors, it exhibited morphological similarities to the sinonasal tumor, leading to the diagnosis of metastatic NC. Cytomorphologic features of NC are limited and can overlap with various small round blue cell tumors. Correct classification is especially pivotal in the era of targeted therapy, considering the ongoing development and evaluation of BET inhibitors targeting BRD4.
摘要：
NUT癌(NC)是一种高度侵袭性、具有t（15:19）易位的低分化癌，导致NUTM1基因的融合。而上消化道沿中线（头部，脖子,胸部,和纵隔)通常被报道为NC的主要部位，随后的病例出现在不同的地点。仅基于形态学实现明确的诊断是具有挑战性的;然而，可以使用对NUT抗体特异性的免疫组织化学（IHC）或通过证明特征性的BRD4::NUTM1融合来实现。准确和及时的诊断可以潜在地告知患者管理和指导治疗。虽然经常发现NC的组织学记录，对其细胞学特征的描述有限。一名39岁的男性，有鼻窦鳞状细胞癌（SCC）病史，通过细针穿刺细胞学（FNA）吸出右侧腮腺肿块。在我们机构审查的先前鼻窦病理学的组织学检查显示原始出现，单调,未分化的细胞具有明显的，突出的核仁.此外,有突发性角化的病灶，伴有明显的嗜中性粒细胞浸润。将SCC的初始诊断重新分类为NC，并通过NUTIHC和分子检测确认。尽管腮腺FNA最初提示多种小圆形蓝色细胞肿瘤的可能性，它表现出与鼻窦肿瘤的形态学相似性，导致转移性NC的诊断。NC的细胞形态学特征有限，可以与各种小的圆形蓝色细胞肿瘤重叠。正确的分类在靶向治疗时代尤其关键,考虑到针对BRD4的BET抑制剂的正在进行的开发和评估。
