本例具有以下特点：
1、青年男性，下肢肿物，最大径1.5cm
2、低倍镜下见界限清楚，中央囊变，具有肿瘤细胞密集区和疏松黏液样变区，局部有模糊结节状。
3、高倍镜下观察到以下特点：（1）中等大小的血管呈管壁玻璃样变性；（2）细胞核有深染、不规则形，但罕见核分裂，类似于退变性核；（3）细胞呈卵圆形、圆形或多角形，粘液样变区可见细胞界限较清，排列方式巢、索状，细胞浆较丰富，红染；（4）可见纤维性中心的菊形团样结构。

诊断：上皮样神经鞘瘤。
免疫组化：做S-100、IV型胶原、Ki-67
鉴别诊断：主要鉴别上皮样MPNST，需镜下计数核分裂，看Ki-67指数。
参考文献：Kindblom LG, Meis-Kindblom JM, Havel G, Busch C.Benign epithelioid schwannoma.Am J Surg Pathol. 1998 Jun;22(6):762-70.
Abstract

Benign schwannoma (neurilemoma) has various morphologic patterns that may cause problems in differential diagnosis. Although an epithelioid variant of malignant schwannoma simulating carcinoma and melanoma is well recognized, a benign counterpart has not yet been defined. In the current study, we describe five cases of benign epithelioid schwannoma that were in the subcutis (four cases) and the neck of the urinary bladder (one case). The tumors occurred in adults 28-73 years of age, were 1-4.5 cm in diameter, were well circumscribed and cellular, and were composed of epithelioid cells arranged in cords and nests. The benign nature of the lesions was evident by a constellation of features, including small size, sharp circumscription, bland morphology, low proliferative activity (four of five had < or =1% Ki67 immunostaining), and a benign clinical course after either marginal or intralesional excision. All cases had some features of classic schwannoma light microscopically and a high degree of Schwann cell differentiation both ultrastructurally and immunohistochemically. The recognition of benign epithelioid schwannoma is important because it may be misinterpreted as a malignant neuroectodermal, mesenchymal, epithelioid, or melanocytic tumor.