恶性外周神经鞘膜瘤的MRI诊断

MRI Diagnosis of Malignant Peripheral Nerve Sheath Tumors

目的总结恶性外周神经鞘膜瘤(MPNST)MRI表现,提高对本病的认识。方法回顾性分析12例经手术、病理证实的MPNST患者的临床和MRI表现。结果 12例中9例合并神经纤维瘤病Ⅰ型。7例发生于脊神经根,1例位于大腿根部,骨盆骶髂骨1例,肘部1例、椎管内髓外硬膜下1例及大腿下段1例。9例(9/12,75%)皮肤、皮下有多发小结节。2例有溶骨性骨质破坏。7例T2WI上肿块沿神经生长,浸润包绕神经,肿块呈纺锤形、多结节融合型,信号混杂,有出血、坏死表现。T2WI上周围多发神经纤维瘤呈蠕虫样、小靶环样。其中恶变的肿块内仍可见"靶征",但结节增大,实性成分增加,周围高信号环缩小或消失,"靶征"变得不典型甚至消失,肿块实性部分强化明显。结论大部分MPNST的临床及MRI具有一定的特点,术前可以诊断。

Objective To explore the MRI manifestations of malignant peripheral nerve sheath tumor（MPNST） and to improve the preoperative diagnostic accuracy.Methods The clinical appearance and MR imagings of 12 cases MPNST proved by operation and pathology were analyzed retrospectively.Results 9/12 cases were associated with Neurofibromatosis type I and mutiply superficial lesions of cutis or sub-cutis were showed on MRI.7/12 lesions located in bilateral nerve roots of spine,1 case located in the root of the thigh,1 case in the pelvic bone,1 case in the elbow,1 case intraspinal tumor and 1 case in the low part of thigh.Two cases massed destroyed the bone.7/12 cases lesions arose in major nerves or nerve root,they expanded the structure in a fusiform fashion.On T2 weighted images,the mutiply benign neurofibromas around the MPNST could be either homogeneously hyperintense or showed a characteristic target sign,consisting of a central hypointense region and looked like a bage of worm.Among them,the MPNST got large,heterogeneity,ill defined margins,and the ＂ target sign＂ got atypical and disappearing.The solid parts of the MPNST showed markedly enhancement after injecting contrast.Conclusion There were typical MRI appearances in most of the MPNST.They were helpful to make the diagnosis.