Periosteal Versus Parosteal Osteosarcoma

Periosteal Osteosarcoma

• femur, tibia
• diaphyseal
• chondroid neoplasm - has high water content
• lower attenuation than muscle on CT
• high signal intensity on T2WI
• broad based soft tissue mass attached to cortex
• cortical thickening and scalloping
• periosteal reaction
• marrow involvement is rare

Parosteal Osteosarcoma

• femur - usually posterior distal aspect
• metaphyseal
• growth tends to be circumferential to bone's surface 
• cleavage plane separates lesion from the cortex
• dense osteoid matrix
• usually has marrow involvement
• low signal on T1WI and T2WI
• higher grade lesions may be high signal on T2WI

REFERENCES

Jelinek JS, Murphey MD, Kransdorf MJ, et al. Parosteal osteosarcoma: value of MR imaging and CT in the prediction of histologic grade. Radiology 1996;201:837-42.

Murphey MD, Jelinek JS, Temple HT, et al. Imaging of periosteal osteosarcoma: radiologic-pathologic correlates. Radiology 2004;233:129-38.