(颈椎)上皮样恶性外周神经鞘瘤:一例报告并文献复习

Epithelioid malignant peripheral nerve sheath tumor: a case report and review of literature

研究背景上皮样恶性外周神经鞘瘤为临床少见的软组织恶性肿瘤,以成年男性多见。肿瘤起源于大神经,主要发生于四肢、头颈部和脊柱,为侵袭性肿瘤,局部复发率高,约有50%的患者可出现远隔部位转移。本文旨在探讨(颈椎)上皮样恶性外周神经鞘瘤的临床病理学特征。方法与结果男性患者,48岁。临床主要表现为肢体无力,以左下肢明显,并伴足踝部肿胀。MRI检查显示C3~5椎管内占位性病变,考虑椎管内肿瘤术后复发。经枕外隆突至C7水平行颈椎椎管内肿瘤切除、硬脊膜修补及椎板减压术。术中可见肿瘤大部位于C3~5水平脊神经前方、左侧椎管内和硬脊膜外,由于部分肿瘤已经固定的钛板开口向前方生长,无法全切除。术后组织形态学观察,肿瘤细胞呈片状或巢团状排列,可见神经纤维分隔,大部分肿瘤细胞呈上皮样、少部分呈梭形,核分裂象易见,部分区域可见灶性坏死。肿瘤细胞弥漫表达波形蛋白、广谱细胞角蛋白、上皮膜抗原、S 100蛋白、突触素和嗜铬素A;不表达肌动蛋白、结蛋白、黑色素瘤相关抗原HMB45、胶质纤维酸性蛋白、孕激素受体、CD34和CD31;Ki 67抗原标记指数>25%;网状纤维染色可见网状纤维包绕上皮样细胞巢;荧光原位杂交检测SS18基因易位阴性。结合病史,最终诊断为(颈椎)上皮样恶性外周神经鞘瘤。结论上皮样恶性外周神经鞘瘤组织形态学表现缺乏特征性,易与其他软组织上皮样肿瘤相混淆,须结合患者临床表现、组织形态学和临床免疫表型综合判断,以免引起误诊或漏诊。S 100蛋白检测虽缺乏特异性,但仍不失为一项诊断上皮样恶性外周神经鞘瘤有价值的指标,广谱细胞角蛋白和上皮膜抗原可呈强阳性表达。

BackgroundEpithelioid malignant peripheral nerve sheath tumor(EMPNST) is a rare malignant soft tissue tumor, and is more common in adult male. EMPNST originates from nerve, mainly located in the limbs, head and neck, and spine. It is an aggressive tumor with high tendency for local recurrence, and about half of the cases appear distant metastasis. This paper aims to investigate the clinicopathological features of cervial EMPNST.Methods and ResultsA 48 year old male mainly presented weakness of limbs, expecially left lower extremty with ankle swelling. MRI showed space occupying lesion in segment C3-5, considering recurrence of intraspinal tumor 2 years after operation. Tumor resection, repairing of spinal dura mater and laminectomy were made from inion to C7 level. It was found during the surgery that most part of the tumor was located in front of C3-5 spinal nerve, left intraspinal and outside of dura mater. Because part of the tumor grew through the opening of titanium plate, the tumor could not be totally removed. According to postoperative histomorphological observation, tumor cells arranged in sheets or nests, and were separated by fibrous tissue. Most tumor cells were epithelioid, while small part of tumor cells were fusiform. Frequent mitotic activity was found, and part of the region appeared focal necrosis. Immunohistochemical staining showed that tumor cells were positive for pan cytokeratin(PCK), epithelial membrane antigen(EMA), vimentin(Vim), synaptophysin(Syn), chromogranin A(CgA), and S 100 protein(S 100); and were negative for actin, desmin(Des), progestrone receptor(PR), glial fibrillary acidic protein(GFAP), CD34, CD31 and HMB45; Ki 67 labeling index was above 25%. Reticular fiber staining showed that the epithelioid cell nests were surrounded by reticular fibers. Fluorescence in situ hybridization(FISH) detection showed negative for SS18 gene translocation. Combining with the history, the final pathological diagnosis was cervical EMPNST.ConclusionEMPNST lacks of morphological characteristics, and needs to be differentiated from a variety of benign or malignant tumors exhibiting epithelioid features. It is considered that clinical materials, morphological features and immunophenotype are helpful to avoid confusion with other similar lesions. S 100 is not a specific marker, but is a valuable diagnostic index. PCK and EMA can present strongly positive expression.