骨外黏液样软骨肉瘤的临床病理学观察

Extraskeletal myxoid chondrosarcoma： a report of 5 cases and review of literature

目的探讨骨外黏液样软骨肉瘤的临床病理特点、免疫表型、病理诊断及鉴别诊断要点。方法收集2008至2013年间5例骨外黏液样软骨肉瘤，对其临床资料、病理组织学及免疫表型（免疫组织化学EnVision法）进行观察并复习相关文献。结果5例中男性2例，女性3例。年龄38～63岁，平均51岁。2例发生于足趾，1例发生于颅眶内，1例发生于大腿，1例发生于肩部。临床上均表现为局部缓慢生长的软组织肿块，术前病程3个月至1年。5例均为单发软组织肿块，瘤体最大径平均5．2em，切面呈结节状，灰白胶冻样。镜下表现较一致，肿瘤均呈分叶状，疏松纤维间隔间为黏液样基质，肿瘤细胞呈单个、小簇状、条索状或疏松网状分布于黏液样背景中，小叶周边的肿瘤细胞较丰富。其中2例瘤组织呈侵袭性生长伴片状出血，例2可见脉管侵犯，瘤细胞丰富，密集排列呈实体状，黏液成分减少，瘤细胞核仁明显，核分裂象（5～10）／10HPF，诊断为细胞型骨外黏液样软骨肉瘤。免疫组织化学：5例肿瘤细胞波形蛋白、线粒体、CD56均阳性；突触素和神经元特异性烯醇化酶在2例弥漫阳性表达，2例灶性阳性；嗜铬粒素A在2例中部分表达，S-100蛋白在2例中灶性阳性，其余3例均不表达；上皮细胞膜抗原仅在1例（例2）中灶性阳性，其余4例均不表达；CD117在1例中弥漫阳性表达，其余4例均不表达。结论骨外黏液样软骨肉瘤是一种罕见的恶性软组织肿瘤，具有特征性的组织病理学特点，可伴有神经内分泌分化。肿瘤虽然生长缓慢，但易局部复发和转移，需长期随访。

Objective To study the clinicopathologic features, immunophenotype and differential diagnosis of extraskeletal myxoid chondrosarcoma （EMC）. Methods The elinicopathologic features of 5 cases of EMC （during the period from 2008 to 2013） were retrospectively analyzed. Immunohistochemical study （EnVision method） was carried out using the archival material. The literature was reviewed. Results There were altogether 3 female patients and 2 male patients. Their age ranged from 38 to 63 years （average = 51 years）. The patients primarily presented with a tender soft tissue mass. All the tumors studied were solitary and the duration of disease onset varied from 3 months to 1 year. The sites of involvement included toe （ number = 2）, intracranial （ number = 1 ）, thigh （ number = 1 ） and shoulder （ number = 1 ）. Gross examination showed white nodular masses with a gelatinous cut surface. The average tumor size measured 5.2 cm in greatest dimension. Histologically, a muhinodular architecture with fibrous or loose fibrovascular septa separating lobules of tumor cells was identified. The lobules contained abundant myxoid stroma, with peripheral accentuation of tumor cellularity. Two cases were diagnosed as cellular variant of EMC, with invasive growth pattern and hemorrhage. The tumor cells in cellular EMC were arranged in solid nodules, with rare myxoid matrix in between. The nuclei were relatively uniform, round to oval and contained prominent nueleoli. The mitotic figure ranged from 5 to 10 per 10 high-power fields. Imnmnohistoehemieal study showed that all of the 5 cases were positive for vimentin, mitoehondria and CD56. Two cases expressed synaptophysin and NSE. Focal positivity for these neuroendocrine markers was detected in the other 2 cases. Chromogranin and S-100 protein expression was demonstrated in 2 cases. The staining for epithelial membrane antigen was positive in case 2 and negative in the other 4 cases. CDll7 showed diffuse positivity in case 1, the other 4 cases were not expressed. Conclusions EMC is a rare soft tissue sarcoma characterized by distinctive histopathologic features and often shows neuroendocrine differentiation. Although EMC is a slow-growing tumor, it carries a high local recurrence rate and even metastases, warranting long-term follow up.