骶椎神经鞘瘤MRI征象与临床病理特征分析

Analysis of magnetic resonance imaging findings and clinicopathologic features of sacral Schwannoma

目的探讨骶椎神经鞘瘤的侵犯特点与MRI表现特征。材料与方法观察26例骶椎神经鞘瘤的MRI表现,根据生长部位、侵犯范围及有无囊变、"足突边缘"征,进行分型、分组测量瘤体最大径。比较型间及组间瘤体最大径的差异。对照分析瘤实质T2WI信号、强化效应及HE染色组织学表现。结果 1型4例,2型5例,3型10例,4型7例。骶前软组织肿块出现率高于骶板后(χ2=13.066,P=0.011)。骶椎中线与中线旁骨质破坏各5例、14例。第3型瘤体最大径大于其他型(t=2.655,P=0.014)。8例巨大侵袭性骶椎神经鞘瘤(giant invasive sacral Schwannoma,GTSS)瘤体最大径超过18例非GISS(t=3.027,P=0.006)。"足突边缘"征阳性12例与阴性14例间瘤体最大径差异无显著性(t=1.896,P=0.07)。囊变组12例的瘤体最大径、病程均长于非囊变组14例(t=2.928,P=0.007;t=-2.187,P=0.039)。Ⅰ区呈T2WI稍高信号、明显强化,对应Atoni A区;Ⅱ区呈T2WI高信号、无强化或轻微强化,对应Atoni B区。结论骶椎神经鞘瘤具有偏心性破坏和骶前侵犯特性。T2WI上稍高信号与高信号及其差异性强化是该瘤的MRI表现特征。

Objective:To assess the invasive feature and characteristic MRI manefistations of sacral schwannoma.Materials and Methods:The maximal dimension of tumoral mass(MDTS)was measured in the 26 patients with sacral schwannoma,who were typed and grouped based on tumoral site and invasive extent,presences of tumoral cystic degeneration and“pod-like margin”sign.The difference s of MDTS between types and between groups were compared.The signal appearances on T2-weighted image and post-contrast enhancement pattern were observed of the tumoral parenchyma,and correlated to histologic findings of HE stain.Results:The 26 patients included 4 cases of type 1,5 of type 2,10 of type 3,and 7 of type 4.The incidence of pre-sacral soft tissue mass surpassed that of post-laminal region(χ^2=13.066,P=0.011).Osteolysis was revealed in midline sacrum in 5 patients and in para-midline sacrum in 14 patients.The MDTS of type 3 was larger than that of rest types(t=2.655,P=0.014).The MDTS of 8 cases of GISS exceeded that of 18 cases of non-GISS(t=-3.027,P=0.006).No significant difference was shown between the 12 patients with"pod-like margin"sign and the 14 patients without the sign(t=1.896,P=0.07).Both MDTS and duration in 12 patients with cystic degeneration exceeded those in 14 with no cystic degeneration(t=2.928,P=0.007.t=-2.187,P=0.039.Respectively).RegionⅠwas demonstrated with mild hyperintensity on T2-weighted image,marked enhancement and correlated to the area of Atoni A,while regionⅡwas noted with hyperintensity on T2-weighted image,mild or no enhancement and correlated to the area of Atoni B.Conclusions:Sacral schwannoma possesses the features of eccentric osteolysis and pre-sacral infiltration.The mild and marked hyperintensities on T2-weighted image,and the intrinsic post-contrast enhancement discrepancy comprise the characteristics of MRI appearances of this tumor.