神经脂肪瘤病的临床病理学特征分析

Lipomatosis of nerve： a clinicopathologic analysis of 15 cases

目的探讨神经脂肪瘤病（NLS）的临床病理学特征。方法对15例NLS的临床表现、影像学特征及病理学特点进行分析。结果15例NLS中男性10例，女性5例，年龄范围4～42岁，平均22．4岁。上肢11例，下肢4例。受累神经以正中神经多见。临床表现为出生后或幼年时发病，多在30岁以前就诊，局部表现为缓慢性生长的肿块，伴有或不伴有感觉和运动障碍，部分病例可伴巨指症及腕管综合征。影像学中以MRI最具特征性，显示受累神经增粗变形，神经束分离，矢状面呈共轴电缆线样，冠状面呈空心面条状外观。大体检查：受累神经明显增粗变形，长短不一，灰黄色，呈结节状、葫芦形、纺锤形、串珠状及粗绳状。镜下观察：病变神经组织中纤维脂肪组织显著增生，包绕并分离神经束，胶原纤维及神经束膜细胞增生并围绕神经束呈同心圆状排列或假洋葱皮样生长；病程较长者，神经束膜显著增厚伴外周高度纤维化，神经组织可呈退行性及萎缩性改变。免疫组织化学显示，所有组织成分均表达波形蛋白，而B．catenin全部阴性；神经纤维表达S-100蛋白、神经微丝及CD56；血管内皮细胞及周围问质树突状纤维表达CD34，而肌特异性肌动蛋白仅表达于血管壁内平滑肌组织。结论NLS是一种较为少见的发生于周围神经的良性软组织肿瘤，影像学表现中以MRI最具有特征性，对NLS的诊断具有较强的提示作用，但最终诊断有赖于组织学确诊。

Objective To study the clinicopathologic features of lipomatosis of nerve （NLS）. Methods The clinical, radiologic and pathologic features were analyzed in 15 cases of NLS. Results There were a total of 10 males and 5 females. The age of patients ranged from 4 to 42 years （ mean age = 22.4 years）. Eleven cases were located in the upper limbs and 4 cases in the lower limbs. The median nerve was the most common involved nerve. The patients typically presented before 30 years of age （ often at birth or in early childhood） with a soft and slowly enlarging mass in the limb, with or without accompanying motor and sensory deficits. Some cases also had macrodactyly and carpal tunnel syndrome. MRI showed the presence of fatty tissue between nerve fascicles, resembling coaxial cable in axial plane and assuming a spaghetti-like appearance in coronal plane. On gross examination, the affected nerve was markedly increased in length and diameter. It consisted of a diffusely enlarged greyish-yellow lobulated fusiform beaded mass within the epineural sheath. Histologically, the epineurium was infiltrated by fibrofatty tissue which separated, surrounded and compressed the usually normal-appearing nerve fascicles, resulting in perineural septation of nerve fascicles and mierofascicle formation. The infiltration sometimes resulted in concentric arrangement of perineural cells and pseudo-onion bulb-like hypertrophic changes. The perineurial cells might proliferate, with thickening of collagen fibers, degeneration and atrophic changes of nerve bundles. Immunohistoehemical study showed that the nerve fibers expressed S-100 protein, neurofilament and CD56 （weak）. The endothelial cells and dendritic fibers were highlighted by CD34. The intravaseular smooth muscle cells were positive for muscle-specific aetin. Conclusions NLS is a rare benign soft tissue tumor of peripheral nerve. The MRI findings are characteristic. A definitive diagnosis can be made with histologie examination of tissue biopsy.