Different and identical features of chondroblastic osteosarcoma and chondrosarcoma: highlights on radiography and magnetic resonance imaging.
BACKGROUND
To identify the different and identical features of 2 tumors with similar pathologic findings, chondroblastic osteosarcoma (OGS) and chondrosarcoma (CSA), with highlights on radiography and magnetic resonance imaging (MRI).


METHODS
Ten patients with chondroblastic OGS and 10 patients with CSA were enrolled. After recording the tumor location, tumor morphology was evaluated for patterns of bony destruction, visible tumor matrix, and aggressive periosteal reactions, endosteal scalloping, cortical expansion, cortical breakthrough and pathologic fracture by radiographic analysis. Signal intensity changes, enhancement pattern, and tumor extensions were evaluated by MRI.


RESULTS
The mean patient ages were 24.7 and 56.7 years in patients with chondroblastic OGS and CSA, respectively (p = 0.001). Tumor occurrence was detected in the appendicular bones in 8 chondroblastic OGS and 3 CSA. Three chondroblastic OGS occurred around the knee (p = 0.003). In addition, there were 6 tumors arising from the metaphysis and 2 arising from the diaphysis in chondroblastic OGS patients. In CSA patients, 1 tumor arose in the metaphysis, 1 in the diaphysis, and 1 in the epiphysis (p = 0.039). On radiographs, visible bone-forming tumor matrix was present in 8 chondroblastic OGS, and coexistence of bone- and cartilage-forming patterns were detected in 2. Visible cartilage-forming tumor matrix was present in 7 CSA, and atypical radiodensity patterns were detected in 2 (p < 0.001). Aggressive periosteal reaction was present in 7 chondroblastic OGS, and non-aggressive periosteal reaction was found in 1 CSA (p = 0.008). MRI revealed the presence of a lobular structure of high signal intensity on T2-weighted images, and peripheral rim and septal enhancement pattern was noted in 2 chondroblastic OGS and 10 CSA patients. Inhomogeneous and marginal enhancement patterns were noted in 6 and 2 chondroblastic OGS, respectively (p = 0.001).


CONCLUSIONS
Metaphysis origin, bone-forming tumor matrix, aggressive periosteal reaction, and young patient age favored chondroblastic OGS. Some chondroblastic OGS showed radiologic and MRI appearances that were typical of CSA.
Yen
Chao-Hsuan
CH
Department of Radiology, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC.
Chang
Cheng-Yen
CY
Teng
Michael Mu-Huo
MM
Wu
Hung-Ta H
HT
Chen
Paul Chih-Hsueh
PC
Chiou
Hong-Jen
HJ
Chiu
Nai-Chi
NC
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D002648:Child; D002813:Chondrosarcoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012516:Osteosarcoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D011859:Radiography; D012189:Retrospective Studies