Radiological features of extraskeletai mesenchymal chondrosarcoma

Objective To explore CT,MRI findings of extraskeletal mesenchymal chondrosarcoma (EMC).Methods Imaging information of all 8 cases of EMC verified by pathology were retrospectively analyzed.Results The location of lesions included lower extremity in 4 cases,forearm in 1 case,trunk in 2 cases and right lung in 1 case.The CT examination was performed in 7 cases,and 5 cases contained different patterns of ring-and-arc,granular,clump or irregular streaky mineralization.Dense calcification was detected in 3 cases,and focal in 2 cases.The nonmineralized component had slightly lower attenuation on CT scans than adjacent muscle.Four cases of peripheral located EMC demonstrated isointense on T1 WI,and mixed signal intensity on T2WI.For the cases of fine and dense calcification in 2 cases,numbers of dot-like low-intensity signals were detected resembling “pepper sign”; while for the cases of focal mineralization in 1 case,the low intensity area was located centrally in the high intensity area.Heterogeneous enhancement was found both in the calcified and uncalcified areas.One case of central located tumor exhibited low and high intensity on T1 and T2 weighted images,and nodual enhancement was observed.Conclusion EMC has several characteristic imaging features,including various mineralization pattern,enhancement of calcified area and signal intensity,which might have diagnostic value for this rare tumor. Key words: Chondrosarcoma;  mesenchymal; Soft tissue neoplasms; Tomography;  X-ray computed; Magnetic resonance imaging