Hirose T, Scheithauer B W, Sano T
First Department of Pathology, University of Tokushima School of Medicine, Japan.
Am J Surg Pathol. 1998 Nov;22(11):1368-78. doi: 10.1097/00000478-199811000-00007.
Most malignant peripheral nerve sheath tumors (MPNST) are schwannian in nature. The pathologic features of MPNST with perineurial cell differentiation remain to be characterized. To determine the clinicopathologic, immunohistochemical, and ultrastructural characteristics of perineurial MPNST, 121 MPNST from the Mayo Clinic Tissue Registry were examined. Of these 23 spindle cell tumors with long processes disposed in whorls or storiform patterns, features typical of perineurioma, were studied. On the basis of immunohistochemistry (epithelial membrane antigen+/S-100-), 5 perineurial MPNST were identified among 23 tumors selected. These and two previously characterized perineurial MPNST are the subject of this study. None of seven tumors was associated with NF-1. Patients included five males and two females ranging in age from 11 to 83 years (mean, 45.7 years). The tumors measured 1.5 to 30 cm (mean, 9.1 cm) and arose in the extremities (two), trunk (two), face (one), mediastinum (one), and retroperitoneum (one). Only one tumor was nerve associated (phrenic nerve). All tumors were surgically removed. No encapsulation or neurofibroma components were noted. Necrosis was seen in three lesions. Four tumors were classified as high-grade malignant and three as low grade. Mitotic indices varied from 1 to 85/10 high-power fields (median, 16). Immunoreactivities included epithelial membrane antigen (100%), vimentin (100%), Leu-7 (57%), and CD34 (14%). Stains for S-100 protein, muscle markers, and cytokeratin were nonreactive. Ultrastructurally, perineurial-like cells were noted in three tumors and cells intermediate between perineurial and Schwann cells in one. Four tumors recurred and two metastasized; no deaths of disease were noted at follow-ups of 28 to 98 months (mean, 66.9). In conclusion, 4% of MPNST show perineurial cell differentiation. An NF-1 association has yet to be described. Nerve involvement is infrequent. Their immunophenotype (epithelial membrane antigen+/S-100-) frequently indicates ultrastructural perineurial differentiation. The prognosis of perineural MPNST appears to be more favorable than that of conventional MPNST.
大多数恶性外周神经鞘瘤（MPNST）本质上是雪旺氏细胞瘤。具有神经束膜细胞分化的MPNST的病理特征仍有待明确。为了确定神经束膜性MPNST的临床病理、免疫组化及超微结构特征，我们检查了梅奥诊所组织登记处的121例MPNST。在这些病例中，研究了23例具有呈漩涡状或束状排列的长突起的梭形细胞瘤，这些是典型的神经束膜瘤特征。基于免疫组化结果（上皮膜抗原阳性/S-100阴性），在所选的23例肿瘤中鉴定出5例神经束膜性MPNST。本研究的对象就是这些病例以及另外两例先前已明确特征的神经束膜性MPNST。7例肿瘤均与神经纤维瘤病1型（NF-1）无关。患者包括5名男性和2名女性，年龄在11至83岁之间（平均45.7岁）。肿瘤大小为1.5至30厘米（平均9.1厘米），发生于四肢（2例）、躯干（2例）、面部（1例）、纵隔（1例）和腹膜后（1例）。仅1例肿瘤与神经相关（膈神经）。所有肿瘤均经手术切除。未发现有包膜或神经纤维瘤成分。3个病灶可见坏死。4例肿瘤被分类为高级别恶性，3例为低级别。有丝分裂指数在每10个高倍视野中为1至85个（中位数为16）。免疫反应性包括上皮膜抗原（100%）、波形蛋白（100%）、Leu-7（57%）和CD34（14%）。S-100蛋白、肌肉标志物和细胞角蛋白染色均为阴性。超微结构上，3个肿瘤中可见神经束膜样细胞，1个肿瘤中有介于神经束膜细胞和雪旺细胞之间的细胞。4例肿瘤复发，2例转移；在28至98个月（平均66.9个月）的随访中未发现因疾病死亡的情况。总之，4%的MPNST表现出神经束膜细胞分化。尚未发现与NF-1有关联。神经受累情况罕见。它们的免疫表型（上皮膜抗原阳性/S-100阴性）常提示超微结构上的神经束膜分化。神经束膜性MPNST的预后似乎比传统MPNST更有利。
