Can imaging distinguish between low-grade and dedifferentiated parosteal osteosarcoma?

Abstract

Compared with low-grade types, dedifferentiated parosteal OGS exhibits a considerably larger tumor size, more sunburst periosteal reaction, and a more frequent development of lung metastasis in the disease course. Tumor size and sunburst periosteal reaction are the most crucial imaging diagnostic factors.

Case Report: Metastatic Parosteal Osteosarcoma in a Dog

“…In humans, imaging can be useful in distinguishing low-grade POSA from higher grade osteogenic malignancies or de-differentiated POSA ( 17 ). On CT imaging, POSA often have characteristic radiolucent areas within these calcified tumors in addition to satellite nodules.…”

“…On CT imaging, POSA often have characteristic radiolucent areas within these calcified tumors in addition to satellite nodules. Low-grade POSA lesions are often smaller than higher-grade or de-differentiated lesions, often do not have pulmonary metastatic disease, and often lack of a sunburst periosteal reaction on imaging ( 17 ). Additionally, more aggressive or dedifferentiated POSA will often have an ill-defined soft tissue mass associated within or adjacent to the primary ossified tumor.…”

Surface bone sarcomas: an update on current clinicopathological diagnosis and treatment

“… 11 Peak incidence is at 20–40 years of age 12 with slight female predominance. 13 It is a low-grade malignant bone-forming tumour occurring on the cortical surface of bone, 6 specifically the outer fibrous layer of the periosteum. Most frequent area is the metaphysis of long bones ( Fig.…”

“…Dedifferentiated PAO is an aggressive high-grade sarcoma with worse prognosis, metastases and high rates of recurrence usually in the form of HGSO, undifferentiated spindle cell or pleomorphic sarcoma with biological behaviour similar to conventional osteosarcoma. 13 , 17 Although different, well-differentiated and dedifferentiated areas often coexist. 5 Characteristic imaging findings include tumour size larger than 11 cm, deeper invasion of the medullary canal and large intralesional radiolucencies on X-rays or CT. 13 , 17 Moreover, novel evidence suggests that dedifferentiation can be correlated with the amplification and expression status of MDM-2 and CDK4.…”

“… 13 , 17 Although different, well-differentiated and dedifferentiated areas often coexist. 5 Characteristic imaging findings include tumour size larger than 11 cm, deeper invasion of the medullary canal and large intralesional radiolucencies on X-rays or CT. 13 , 17 Moreover, novel evidence suggests that dedifferentiation can be correlated with the amplification and expression status of MDM-2 and CDK4. 31 …”