摘要目的：探讨骨外黏液样软骨肉瘤（ extraskeletal myxoid chondrosarcoma ， EMC）的临床病理特征、诊断、鉴别诊断。方法收集2005至2015年福建省立医院与南京军区福州总医院7例EMC，进行组织形态学、免疫组织化学及特殊染色检查，并随访及复习相关文献，进行综合分析。结果1例女性和6例男性，年龄21～50岁（中位年龄36岁），肿块最大径2.5～15.0 cm（平均8.4 cm）。肿块分别位于：左颈、右肩、左股骨、右上臂、腹腔、左股骨、右股骨。除例3表现为疼痛和酸胀，例5表现为腹痛外，其余5例均表现为无痛性肿块。病理组织学上，本组7例手术切除标本，病理组织学表现相似，低倍镜下，肿瘤呈结节状或分叶状，间质见大量黏液样基质。肿瘤细胞排列呈片状、巢状、簇状或星网状。瘤细胞呈梭形、短梭形、卵圆形、上皮样、横纹肌样（或浆细胞样）。胞质少到中等，胞质淡染，部分胞质丰富，嗜酸性，可见胞质内空泡或胞质内嗜酸性包涵体。核分裂象少见（一般＜2／10 HPF），可见坏死。肿瘤浸润周围横纹肌及脂肪组织。其中1例表现为上皮型，2例肿瘤富于细胞（富于细胞型），细胞丰富，生长活跃，细胞呈上皮样，胞质丰富，染色质增粗，核质比增高，核分裂象多见，核仁清晰可见。免疫表型：肿瘤细胞呈波形蛋白（7／7）及INI1（7／7）阳性，少数呈广谱细胞角蛋白（2／7）、p63（3／7）、CD99（3／7）、S-100蛋白（1／7）及突触素（2／7）阳性，Ki-67阳性指数10％～40％。α-平滑肌肌动蛋白、结蛋白、myoD1、CD34和CD117均阴性。5例（5／7）检测到EWSR1基因信号。例5未检测到MDM2基因扩增信号。例6和7未检测到SSX-SYT融合基因信号。结论 EMC属于罕见恶性间叶源性肿瘤，确诊主要依靠形态学及免疫组织化学标志物，必要时分子病理学检查有帮助。临床及病理均需与骨旁软骨肉瘤、混合瘤／肌上皮瘤／肌上皮癌、脊索瘤、黏液性脂肪肉瘤、软骨样脂肪瘤、黏液性上皮样肉瘤等肿瘤相鉴别，治疗以手术切除为主，预后较好。

abstractsObjective To study the clinicopathologic features , diagnosis and differential diagnosis of extraskeletal myxoid chondrosarcoma ( EMC) .Methods The clinical and pathologic features of 7 cases of EMC encountered in Fujian Provincal Hospital and Fuzhou General Hospital of Nanjing Military Command during the period of 2005 to 2015 were analyzed .Immunohistochemical study and PAS staining were carried out.Relevant literature was reviewed .Results The male-to-female ratio was 6 to 1.The age of patients ranged from 21 to 50 years ( median =36 years ) .The maximum tumor dimension ranged from 2.5 to 15.0 cm (mean =8.4 cm).The sites of involvement included left neck , right shoulder, left thigh, right thigh, right upper arm and abdomen.Most patients presented with painless lumps.Histologically, all cases showed similar features.Low-power examination showed a nodular or lobulated architecture , with intervening fibrous septa and myxoid matrix in the background.The tumor cells were arranged in cords or tufted clusters.They were spindly to epithelioid /rhabdoid ( plasmacytoid ) in shape, with eosinophilic to sometimes vacuolated cytoplasm.Intracytoplasmic eosinophilic inclusion bodies and coagulative necrosis were focally seen.Mitotic figures were rare ( less than 2 per 10 high-power fields ) .Immunohistochemical study showed that the tumor cells were positive for vimentin (7/7) and INI1 (7/7).They were focally positive for CKpan (2/7), p63 (3/7), CD99 (3/7), S-100 protein (1/7) and synaptophysin (2/7).Ki-67 proliferation index ranged from 10%to 40%.The tumor cells were negative for α-smooth muscle actin, desmin, myoD1, CD34 and CD117.The cytoplasm of the tumor cells was positive for PAS .EWSR1 gene signal was detected in 5 cases.Conclusions EMC is a rare malignant mesenchymal tumor .Arrival at correct diagnosis relies on morphologic examination and immunohistochemistry .Molecular pathology is helpful when necessary .The primary treatment modality for EMC is complete surgical excision and the prognosis is satisfactory .