腹膜后骨外骨肉瘤临床病理特征和鉴别诊断

Clinicopathologic features and differential diagnosis of retroperitoneal extraskeletal osteosarcoma

目的探讨腹膜后骨外骨肉瘤的临床病理特征、鉴别诊断、治疗和预后。方法对1例腹膜后骨外骨肉瘤的临床资料、病理特点及免疫组化标记进行分析。结果患者临床表现为腹膜后巨大肿物。巨检示肿瘤有假包膜,切面灰白质硬;镜下示肿瘤细胞呈梭形,卵圆形及多角形,胞浆嗜酸性,核呈卵圆形、染色质细腻,无明显核仁,核分裂像易见,瘤细胞产生的骨样基质相互连接成花边状、网格状。免疫组化:瘤细胞波形蛋白(Vimentin)和CD99(+),S-100蛋白、平滑肌肌动蛋白(SMA)、CD34、角蛋白(CK)均为(-),Ki-67阳性细胞指数为15%。结论腹膜后骨外骨肉瘤是一种罕见的高度侵袭性恶性肿瘤,诊断上应与转移性骨肉瘤、骨化性肌炎和恶性间叶瘤等鉴别,免疫组化染色有助于明确诊断。

Objective To investigate the clinicopathologic features,differential diagnosis,therapy and prognosis of retroperitoneal extraskeletal osteosarcoma（ EO）. Methods clinical data,pathological features and immunohistochemical markers were analyzed in 1 case of retroperitoneal EO patient. Results The patient presented enormous retroperitoneal tumor. General observation showed the tumor had pseudocapsule and the cut surface appeared grayish-white and hard. Microscopically,the tumor had the shape of diamond,ovoid or polygon with eosinophilic cytoplasm and oval nuclei containing fine chromatin,without obvious nucleoli but with many mitosis. In addition,the osteoid marix produced by the tumor cells was irregular lace-like or with reticular pattern. Immunohistochemically,the tumor cells were positive for Vimentin,positive for CD99 but negative for S-100,SMA,CD34 and CK. The Ki67 positive rate was 15%. Conclusion Retroperitoneal extraskeletal osteosarcoma is a rare and highly invasive tumor. It should be distinguished from metastatic osteosarcoma,myositis ossificans and malignant mesenchymoma. The immunohistochemical staining is helpful for its diagnosis.