腹膜后神经源性肿瘤的分类以及CT诊断和鉴别诊断

目的：本文探讨腹膜后不同神经源性肿瘤的影像学表现、血液动力学特征及其与病理的关系,以提高诊断准确性。方法：经手术病理证实的腹膜后神经源性肿瘤43例,12例术前经螺旋CT或多排螺旋CT平扫和增强扫描,31例经平扫、动脉期和门脉期扫描。注射流率2～3ml/s。复习CT扫描结果并和手术病理作回顾性对照分析。结果：43个病例中神经鞘膜来源肿瘤28例（良性神经鞘瘤19例,恶性神经鞘瘤7例,神经纤维瘤2例）;副神经节瘤9例（良性8例,恶性1例）;交感神经节细胞来源肿瘤6例（节细胞神经瘤2例,神经母细胞瘤4例）。神经鞘膜来源肿瘤由低密度的细胞稀疏区和中等密度的细胞密集区构成,两种结构强化程度不同;神经鞘瘤多呈圆形,神经纤维瘤呈丛状或不规则形;良性肿瘤境界清楚,恶性神经鞘瘤境界不清,可见晕样结构和毛刺。副神经节瘤实体部分密度偏高,密度与腹主动脉相仿,变性明显,强化显著;良性和恶性难以鉴别。交感神经节细胞来源肿瘤富含水分,形态不规则,密度低;节细胞神经瘤密度较均匀,境界清楚,容易铸型并形成伪足样突起,强化轻微;神经母细胞瘤密度不均匀,境界不清,容易包绕血管和脏器,钙化显著,分叶明显,呈不均匀轻中度强化。神经节神经母细胞瘤影像表现介于节细胞神经瘤和神经母细胞瘤之间。结论：腹膜后神经源性肿瘤包括神经鞘膜来源肿瘤,副神经节瘤和交感神经节细胞来源肿瘤。不同神经源性肿瘤的影像表现既有相似之处又存在区别,结合肿瘤的病理基础,突出其根本征象并与其他征象结合,有助于提高诊断的准确性。

Retroperitoneal neurogenic neoplasms:classification,CT diagnosis and differential diagnosis

Objective：To explore the classification,CT diagnosis and differential diagnosis of retroperitoneal neurogenic tumors so as to improve CT diagnostic accuracy.Methods：43 cases with retroperitoneal neurogenic tumor confirmed by surgical pathology underwent spiral CT plain scanning and enhancement scanning before operation,the CT data were reviewed and analysed retrospectively in correlation with surgical and pathological results.Results：Of 43 cases,19 were found to be benign schwannoma,7 magligant schwannoma,2 neurofibroma,9 paraganglioma,4 neuroblastoma,2 ganglioneuroma.Tumors originating from the nerve sheath were composed of hypocellular zone and hypercellular area,the density and enhancement degree of the two areas were varied.Benign schwannoma depicted round in shape with well-defined margin,neurofibroma presented fasciculate or irregular in shape with well-defined margin,malignant schwannoma showed irregular or round in shape with ill-defined margin （halo,spiculation）.Paraganglioma demonstrated high density with obvious degeneration （cystic change,necrosis,calcification,hemorrhage） on CT unenhanced scan,striking enhancement after injection of contrast materials.Ganglioneuroma with well-defined margin showed a tendency of wedging into the space between adjacent organs or structures,and presented very low density on unenhanced CT scan,slight enhancement on enhancement scan.Neuroblastoma demonstrated low density,lobulated masses with obvious calcification and ill-defined margin on non-enhanced CT,and nonuniform enhancement with major blood vessels encased after injection of contrast materials.Conclusion：Retroperitoneal neurogenic tumors originate from the nerve sheath,parasympathetic ganglion and the neural crest of sympathic ganglia,respectively.Differences and similarities of CT findings are always present,combining the characteristic CT findings with the common CT findings is helpful for diagnosis and differential diagnosis.