目的:探讨骨外骨肉瘤的影像学表现及其特点。方法:回顾性分析4例骨外骨肉瘤的临床资料及其影像表现。结果:4例均有巨大软组织肿块,其内可见棉絮状或斑片状、小结节状致密阴影,邻近骨骼无变化。结论:软组织巨大肿块内多形态致密阴影存在,应考虑骨外骨肉瘤可能,注意与骨化性肌炎相鉴别。 Objective: To investigate the imaging features and characteristics of osteosarcoma. Methods: The clinical data and imaging findings of 4 cases of osteosarcoma were retrospectively analyzed. Results: There were huge soft tissue mass in 4 cases, which could be seen as cotton wool or patchy, nodular dense shadow with no changes in the adjacent bones. Conclusion: There are many morphologically dense shadows in the huge mass of soft tissue. The possibility of extraosseous osteosarcoma should be considered, and attention should be paid to the differentiation of myositis ossificans.