原发腹膜后恶性神经鞘瘤的MSCT表现及其病理基础

MSCT findings of primary retroperitoneal malignant nerve sheath tumor with pathologic correlation

目的：分析腹膜后恶性神经鞘瘤的多排螺旋CT表现,以提高诊断准确性。方法：经手术病理证实的腹膜后恶性神经鞘瘤8例,术前经多排螺旋CT平扫和增强扫描,注射流率采用1.5-3.5 ml/s;仔细复习CT扫描结果并和手术病理作回顾性对照分析。结果：8例肿瘤均为单发,肿瘤呈圆形或椭圆形7例,不规则分叶形1例,5例肿瘤前缘较光整,3例不光整,8例后缘均欠规则,侵及周边脂肪间隙或后腹壁,隐约见不规则毛刺样改变,4例后缘见角状、伪足样突起侵入后腹壁细胞稀疏区;实性肿瘤5例,囊实性2例,囊性1例,2例见钙化;肿瘤平扫密度不均匀7例,较均匀1例,但均低于肌肉组织,3例见不规则片状低密度坏死区;增强动脉期均明显不均匀强化,与肌肉组织相仿或稍高;静脉期强化进一步持续并略加强。1例腹膜后见有多个淋巴结肿大并明显强化。结论：腹膜后恶性神经鞘瘤有包膜,坏死囊变显著,CT密度低于大多数软组织肿瘤,强化明显;恶性征象包括虽在神经通路却不与神经相连,肿瘤边缘小毛刺,邻近脂肪间隙和肌肉肿瘤浸润,邻近淋巴结增大,富细胞区坏死、钙化并呈伪足样侵入细胞稀疏区。

Objective：To explore the MSCT findings of retroperitoneal malignant schwannoma and to improve the diagnostic accuracy.Methods：Eight cases with retroperitoneal malignant schwannoma confirmed by surgical pathology underwent spiral CT plain scanning and enhancement scanning before operation,the CT data were reviewed and analyzed retrospectively in comparison with surgical and pathological results.Results：Among 8 cases,7 masses were round or oval,1 mass with irregular lobulation.Five masses had smooth anterior edge,3 masses had coarse anterior edge.All 8 masses had irregular posterior edge,and intruded into the adjacent fatty tissue or posterior abdominal wall.Five masses were solid,1 mass was cystic,2 masses had mixed density.Two masses had calcification.Seven masses had inhomogeneous density on pre-contrast scan.The density of all tumors was lower than that of muscle.With contrast enhancement,all the tumors were enhanced notably and inhomogeneously in arterial phase,and continuely enhanced in venous phase.One case had multiple retroperitoneal enlarged lymph nodes,which were enhanced notably.Conclusion：Retroperitoneal malignant schwannoma typically shows obvious necrosis,cystic change and obvious heterogeneous enhancement after intravenous contrast administration.