Varma D G, Ayala A G, Guo S Q, Moulopoulos L A, Kim E E, Charnsangavej C
Department of Diagnostic Radiology, University of Texas M. D. Anderson Cancer Center, Houston 77030.
J Comput Assist Tomogr. 1993 May-Jun;17(3):414-7. doi: 10.1097/00004728-199305000-00015.
We report four cases of extraskeletal osteosarcoma of the thigh to illustrate MRI findings of this rare neoplasm. Calcifications or osteoid material were not discernible in these tumors on MRI or conventional radiography. Three tumors were well demarcated on MRI and corresponded to pseudoencapsulation on radiologic-pathologic correlation. These three tumors were heterogeneous in appearance and were hyperintense to muscle on T1-weighted imaging and demonstrated high signal intensity on T2-weighted imaging. In the fourth tumor, which occupied almost the entire thigh, MRI before and after intravenous gadopentetate dimeglumine administration revealed cystic, hemorrhagic, and solid components. Pathological examination revealed a cystic hemorrhagic cavity containing necrotic and viable tumor and a large solid tumor component. The MRI findings in extraskeletal osteosarcoma are non-specific. However, in the appropriate age group the differential diagnosis of a soft-tissue mass in the thigh should include extraskeletal osteosarcoma, even in the absence of radiographically discernible calcifications or osteoid material within the soft-tissue mass.
我们报告4例大腿部骨外骨肉瘤病例，以阐述这种罕见肿瘤的MRI表现。在这些肿瘤的MRI或传统X线片上均未发现钙化或骨样物质。3例肿瘤在MRI上边界清晰，在放射学-病理学对照中对应假包膜。这3例肿瘤外观不均质，在T1加权像上相对于肌肉呈高信号，在T2加权像上呈高信号强度。在第4例几乎占据整个大腿的肿瘤中，静脉注射钆喷酸葡胺前后的MRI显示有囊性、出血性及实性成分。病理检查显示一个含有坏死及存活肿瘤的囊性出血腔和一个大的实性肿瘤成分。骨外骨肉瘤的MRI表现无特异性。然而，在适当的年龄组，大腿部软组织肿块的鉴别诊断应包括骨外骨肉瘤，即使在软组织肿块内无放射学可发现的钙化或骨样物质时也应考虑。
