MRI对下肢软组织良、恶性神经鞘瘤的诊断价值

Diagnostic Value of MRI in Lower Limb Soft Tissue Benign and Malignant Schwannoma

目的分析下肢软组织良、恶性神经鞘瘤的MRI表现及鉴别诊断要点,以提高对下肢软组织良、恶性神经鞘瘤的诊断及其鉴别诊断水平。方法搜集本院经穿刺活检或手术病理证实的下肢软组织神经鞘瘤15例,对其形态、大小、边界、信号特征、深筋膜完整性等进行综合分析,并与病理学进行对照。结果 15例下肢软组织神经鞘瘤,其中良性11例(囊性1例,囊实混合性7例,实性3例),MRI显示瘤体边缘清晰光滑,周围均见完整的纤维包膜,下肢软组织深筋膜结构完整,由于瘤体内束状区(Antoni A区)及网状区(Antoni B区)分布及含量多少的不同,T1WI呈等、稍低信号,T2WI呈等或高信号,其中5例见"靶征",2例见"神经出入征",4例见"脂肪分离征"。15例中恶性4例,瘤体直径均超过5cm,均为囊实性,无完整包膜,T1WI呈以等、低信号为主混杂信号,T2WI呈以等、稍高信号为主的混杂信号,1例见"神经出入征",4例见"脂肪分离征"、脂肪水肿及深筋膜结构破坏。结论下肢软组织内良、恶性神经鞘瘤具有一定MRI特征,结合多种影像征象可提高正确诊断率。

Objective Summarize the Magnetic Resonance Imaging features and differential diagnostic points of malignant and benign schwannomaoriginated from soft tissue in Lower limbs to improve our diagnostic skills. Methods 15 patients with histologically proven malignant and benign schwannoma were retrospectively reviewed. Special attention was paid to gross appearance; size of the lesions; edge; signal characteristics; involvement of deep fascia. And these lesions were then compared to the pathological findings. Results 11 benign lesions of the 15 cases （one cystic lesion,7 lesions combined with both cystic and solid components, 3 solid lesions）,they showed smooth edge and intact fibrous capsule with intact deep fascia. And they showed iso/slightly lower signals on T1WI and iso/slightly higher signals on T2WI due to the location and content of both fasciculation of Antoni A region and net structure of Antoni B region, of which 5 cases showed the”target sign”,2 cases showed the＂tubular entering and exiting sign＂and 4 cases showed＂spilt-fat sign＂. 4 of the 15 lesions were malignant, there diameter were all exceed 5cm, and were all solid lesions, with incompleted capsule. They Showed mixed predominantly lower signal on T1WI and higher signal T2WI, one case showed the＂tubular entering and exiting sign＂,4 cases showed ＂spilt-fat sign＂ and lipedema, 3 cases invaded deep fascia. Conclusions There are characteristic Magnetic Resonance Imagingfeatures of malignant and benign schwannoma originated from soft tissue in Lower limbs, a combined analyse of image signs help to improve diagnostic accuracy of the disease.