髓内黑色素性神经鞘瘤

Intramedullary melanotic schwannoma

目的报告1例髓内黑色素性神经鞘瘤患者,结合文献探讨其临床和组织病理学特征、诊断与鉴别诊断、治疗原则。方法与结果男性患者,47岁,胸椎椎管内占位性病变切除术后6年、背部疼痛1年。脊椎MRI显示T4～5平面髓内占位性病变。手术全切除肿瘤。组织学形态观察,肿瘤细胞呈梭形或上皮样,排列成片状、巢团状或交织状,胞质内含数量不等的黑色素颗粒,胞核呈圆形或卵圆形,可见小核仁,未见核分裂象。免疫组织化学染色,肿瘤细胞S-100蛋白、黑色素瘤相关抗原HMB45、黑色素-A和Ⅳ型胶原蛋白呈阳性,上皮膜抗原、胶质纤维酸性蛋白、CD57、孕激素受体、结蛋白和肌浆蛋白呈阴性,Ki-67抗原标记指数约为10%。超微结构观察,肿瘤细胞可见连续基膜,胞质内含不同成熟程度的黑色素小体。最终病理诊断为髓内黑色素性神经鞘瘤。随访18个月,肿瘤无复发。结论髓内黑色素性神经鞘瘤临床罕见,其诊断依靠组织学形态、免疫表型和超微结构特征,应注意与黑色素瘤、黑色素细胞瘤和色素性神经纤维瘤相鉴别。髓内黑色素性神经鞘瘤生物学行为较难预测,可局部复发,应对患者进行长期密切随访。

Objective To study the clinicopathologic features,diagnosis,differential diagnosis,treatment and prognosis of intramedullary melanotic schwannoma（IMS）.Methods and Results A 47-yearold male underwent an excision of thoracic intraspinal space-occupying lesion 6 years ago and was admitted to the hospital with a history of low back pain for one year.Spinal MRI revealed an intramedullary mass at the level of T_（4-5）.Gross total resection of the tumor was done.Histological findings revealed that spindle or epithelioid cells were arranged in sheets,nests or intersecting bundles.The cytoplasms contained varying amounts of melanin pigments.The nuclei were round to oval with small nucleoli but no mitotic figures.Immunohistochemically,the tumor cells were positive for S-100 protein（S-100）,HMB45,Melan-A,and Collagen Ⅳ.They were negative for epithelial membrane antigen（EMA）,glial fibrillary acidic protein（GFAP）,CD57,progestrone receptor（PR）,desmin（Des） and myogen.Ki-67 labeling index was about 10%.Ultrastructural findings revealed that the tumor cells were surrounded by continuous basal lamina,and melanin granules in different stages of maturity were present in the cytoplasms.Final pathological diagnosis was IMS.No recurrence of tumor was found after follow-up for 18 months.Conclusions Intramedullary melanotic schwannom is a rare neoplasm.The diagnosis relies on its morphological characteristics,immunophenotype and ultra microstructure,and should be differentiated from melanoma,melanocytoma and pigmentary neurofibroma.The biologic behavior of the tumor is difficult to predict.It may occur local recurrence.Therefore,long-term follow-up is required.