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Abstract：
Introduction Biphenotypic sinonasal sarcoma (BSNS) is a recently found entity that first described by Lewis et al. It was then added to the 4th edition of the World Health Organization (WHO) of head and neck tumors in 2012. BSNS has been described as a rare low-grade sarcoma arising in the upper sinonasal tract. It is believed that in the past, BSNS was, likely, previously diagnosed as other low-grade or benign malignancies. Fibrosarcoma, leiomyosarcoma, and peripheral nerve sheath tumors, all fall within the differential diagnosis of BSNS. However, BSNS is unlike other mesenchymal sinonasal tumors, as it displays both neural and myogenic differentiation. BSNS has thus far been recognized in only a hand full of case reports, all of which have reported similar morphologic features of a low-grade soft tissue tumor with neural involvement arising from the nasal cavity or ethmoid air cells in middle aged individuals. In fact, being low-grade sarcoma became such a hallmark characteristic of this tumor that it even received the name low-grade sinonasal sarcoma with neural and myogenic features or LGSSNMF. Case Presentation We present, however, for the first time, a high-grade differentiation of BSNS in an otherwise healthy 72-year-old female. The patient was referred from an outside ENT (ear, nose, and throat) after pathology from a presumed polypectomy returned positive for a BSNS. Initial imaging revealed erosion through the bilateral lamina papyracea, anterior cranial fossa floor, and posterior table of the frontal sinus. She then underwent a combined endoscopic and bicoronal open approach for resection of the skull base lesion that was found to encompass the entirety of the sinonasal cavities bilaterally. Postoperatively, the patient underwent significant complications including infection of the pericranial flap, pneumocephalus, and eventually death. Discussion As BSNS is a fairly new entity, currently there has only been four case series conducted, each identifying features of a low-grade sarcoma with both myogenic and neural differentiation. Histologically, BSNS has monophasic spindle cells with uniform, elongated nuclei with scant cytoplasm between benign proliferations of surface-type respiratory epithelium, with a low mitotic rate. Our case, however, revealed pleomorphic hyperchromatic cells with high mitotic activity and necrosis with invasion of bone, staging it as high grade. Immunohistochemistry also differed from the previously reported standards. This case describes a new category for BSNS which may change the differential diagnosis, management, and surgical recommendations that are currently utilized for this skull base neoplasm.
摘要：
简介双表型鼻窦肉瘤（BSNS）是最近发现的实体，首先由Lewis等人描述。然后将其添加到2012年世界卫生组织（WHO）的第4版头颈部肿瘤中。BSNS已被描述为一种罕见的低度肉瘤，出现在上鼻窦道。相信在过去,BSNS是，很可能,以前诊断为其他低度或良性恶性肿瘤。纤维肉瘤,平滑肌肉瘤,和周围神经鞘瘤，均属于BSNS的鉴别诊断范围。然而,BSNS不同于其他间叶性鼻窦肿瘤，因为它显示神经和肌源性分化。迄今为止，BSNS仅在大量病例报告中得到认可，所有这些都报道了中年人的低度软组织肿瘤的形态特征相似，该肿瘤由鼻腔或筛骨空气细胞引起神经受累。事实上,低度肉瘤成为该肿瘤的标志性特征，甚至被称为具有神经和肌源性特征的低度鼻窦肉瘤或LGSSNMF。案例介绍我们介绍，然而,第一次,一名健康的72岁女性的BSNS高度分化。患者从外部耳鼻喉科(耳朵，鼻子,和喉咙）推测的息肉切除术后的病理学对BSNS呈阳性。最初的成像显示通过双侧薄层纸莎草被侵蚀，前颅窝底,额窦的后表。然后，她接受了内窥镜和双冠状开放联合方法，以切除颅底病变，该病变被发现两侧覆盖了整个鼻窦腔。术后,患者经历了严重的并发症，包括颅周皮瓣感染，气颅,最终死亡。讨论由于BSNS是一个相当新的实体，目前仅进行了四个案例系列，每个识别具有肌源性和神经分化的低度肉瘤的特征。组织学上,BSNS具有均匀的单相梭形细胞，表面型呼吸上皮良性增殖之间的细胞核细长，细胞质稀少，有丝分裂率低。我们的案子,然而,显示多形性超染细胞有丝分裂活性高，坏死侵犯骨，将其归类为高级。免疫组织化学也不同于先前报道的标准。这个案例描述了一个新的BSNS类别，这可能会改变鉴别诊断，管理,以及目前用于这种颅底肿瘤的手术建议。
