外周神经鞘膜肿瘤超声误诊分析

Analysis of ultrasonographic misdiagnosis of peripheral nerve sheath tumor

目的分析外周神经鞘膜肿瘤(PNST)的声像图特点,探讨其超声误诊的原因。方法选取经手术及病理证实的PNST患者36例,应用超声观察肿块的位置、大小、形态、边界、内部回声及彩色多普勒血流情况,重点观察其与毗邻组织关系;以病理诊断结果为金标准,分析PNST的超声误诊原因。结果 36例PNST中,神经鞘瘤31例,神经纤维瘤4例(神经纤维瘤病Ⅰ型3例),神经纤维肉瘤1例。术前超声明确诊断15例;误诊为淋巴结9例(其中包括淋巴瘤1例),皮脂腺囊肿2例,颈动脉体瘤1例,肌纤维瘤1例;余8例因对该病及其周围结构认识不足,未明确提示。PNST主要超声特点包括:130例肿块呈类圆形或椭圆形且边界清晰,其中11例肿块长轴一端或两端见细尾状低回声,呈明显"鼠尾征";231例神经鞘瘤均表现为内部回声均匀或不均匀,以低回声为主;312例肿块可见周围血管受压移位;413例肿块内探及丰富血流信号;5神经纤维瘤病Ⅰ型均表现为皮肤和皮下组织增厚,其肿块呈高低回声间杂有序的"羽毛状"排列。结论全面了解PNST患者的临床资料、解剖结构和超声表现,细致化超声检查,可以降低其超声的误诊率。

Objectives To study the ultrasonographic characteristics and the cause of misdiagnosis of peripheral nerve sheath tumor（PNST）. Methods Thirty- six patients with PNST examined with ultrasound and confirmed by operation and pathology were recruited. The position,size,shape,border,internal echo and color Doppler blood flow were observed,especially the relationship between the tumor and its adjacent tissues. The cause of misdiagnosis by ultrasound were analyzed with pathological results as the gold standard. Results In all 36 cases of PNST,there were 31 cases of schwannoma,4 case of neurofibroma（3 cases of neurofibromatosis type 1）,1 case of neurofibrosarcoma. Fifteen cases were definitely diagnosed by ultrasound before operation,9 cases were misdiagnosed as lymph nodes（including 1 case of lymphoma）,2 cases as sebaceous cyst,1 case was misdiagnosed as carotid body tumor,and 1 case as myofibroma before operation,8 cases were not clearly diagnosed for poor cognition of this disease or surrounding structures. The main ultrasonographic features of PNST included：①the lesion presenting as round or oval in shape with well-defined margins were shown in 30 cases,one or two sides could show slender hypoechoic area in long axis of mass in 11 cases,also known as ＂tail of mouse＂sign;②31 cases of schwannoma commonly present with homogeneous or inhomogeneous internal echoes,mostly hypoechoic;③displaced and compressed surrounding blood vessels were shown in 12 cases;④plenty of blood flow signals were shown in 13 cases;⑤all cases with neurofibromatosis type 1 showed thickened skin and subcutaneous tissues,feather-like hyper-/hypoechoic pattern. Conclusion It could avoid misdiagnosis through full understanding of clinic information,anatomy and ultrasonographic characteristics of PNSTs,with carefully observation during examination.