Answer for BIR CoW 04 Jul 2021
Periosteal osteosarcoma
Findings:
Tumor in the femoral metadiaphysis with a Codman triangle at its edge and perpendicular periosteal reaction . Cortical scalloping noted in the anterior cortex. Soft-tissue masses are well defined and surrounded a median of 50%–55% of the cortex – Wrap around sign ( vs circumferential erosion in high grade os). Lesions shows high signal intensity on T2-weighted MR images , reflecting the high water content of these largely chondroblastic lesions.
Discussion:
Periosteal OS is the second most common type of juxtacortical OS, accounting for 1.5% of all OS cases. It typically affects patients in the 2nd or 3rd decade of life, with a characteristic location along the metadiaphyses of long bones , most commonly the tibia . The prognosis for periosteal OS (83% 5-year survival rate) is better than that for conventional OS but worse than that for parosteal OS.Periosteal OS arises from the inner, germinative layer of periosteum . The tumor is predominantly cartilaginous, and its cytologic grade is intermediate, or grade 2 —a grade distinctly lower than that of conventional OS but higher than that of parosteal OS. Common radiographic findings include a soft-tissue mass with periosteal reaction, cortical erosion, and cortical thickening . Periosteal reaction often extends perpendicularly from the inner cortex to the outer margin of the tumor. The predominantly chondroid matrix of this tumor results in a lesion that is low in attenuation on CT images and hyperintense on T2-weighted MR images , with smaller foci of low signal intensity on MR images representing calcified matrix or hair-on-end periosteal reaction. Cortical scalloping and perpendicular periosteal reaction extending into the soft-tissue mass. Soft-tissue masses are well defined and surrounded a median of 50%–55% of the cortex – Wrap around sign ( vs circumferential erosion in high grade os). Lesions commonly show low attenuation at CT and high signal intensity on T2-weighted MR images , reflecting the high water content of these largely chondroblastic lesions. Focal areas of adjacent marrow replacement are common at MR imaging but represented reactive changes unless they were in direct continuity with the overlying soft-tissue mass. Periosteal vs paraosteal OS: Parosteal OS is a densely ossified juxtacortical mass that lies outside the cortex and occurs in metaphyses whereas periosteal OS is usually more lytic in appearance, causing cortical erosion and periosteal reaction, and occurs in metadiaphyses. Periosteal vs high grade surface OS: High-grade surface OS often involves the entire circumference of the cortex and is more likely to show medullary invasion. Furthermore, the presence of a high histologic grade, identical to that of conventional OS, throughout the entire tumor is diagnostic of high-grade surface OS.
Findings:
Tumor in the femoral metadiaphysis with a Codman triangle at its edge and perpendicular periosteal reaction . Cortical scalloping noted in the anterior cortex. Soft-tissue masses are well defined and surrounded a median of 50%–55% of the cortex – Wrap around sign ( vs circumferential erosion in high grade os). Lesions shows high signal intensity on T2-weighted MR images , reflecting the high water content of these largely chondroblastic lesions.
Discussion:
Periosteal OS is the second most common type of juxtacortical OS, accounting for 1.5% of all OS cases. It typically affects patients in the 2nd or 3rd decade of life, with a characteristic location along the metadiaphyses of long bones , most commonly the tibia . The prognosis for periosteal OS (83% 5-year survival rate) is better than that for conventional OS but worse than that for parosteal OS.Periosteal OS arises from the inner, germinative layer of periosteum . The tumor is predominantly cartilaginous, and its cytologic grade is intermediate, or grade 2 —a grade distinctly lower than that of conventional OS but higher than that of parosteal OS. Common radiographic findings include a soft-tissue mass with periosteal reaction, cortical erosion, and cortical thickening . Periosteal reaction often extends perpendicularly from the inner cortex to the outer margin of the tumor. The predominantly chondroid matrix of this tumor results in a lesion that is low in attenuation on CT images and hyperintense on T2-weighted MR images , with smaller foci of low signal intensity on MR images representing calcified matrix or hair-on-end periosteal reaction. Cortical scalloping and perpendicular periosteal reaction extending into the soft-tissue mass. Soft-tissue masses are well defined and surrounded a median of 50%–55% of the cortex – Wrap around sign ( vs circumferential erosion in high grade os). Lesions commonly show low attenuation at CT and high signal intensity on T2-weighted MR images , reflecting the high water content of these largely chondroblastic lesions. Focal areas of adjacent marrow replacement are common at MR imaging but represented reactive changes unless they were in direct continuity with the overlying soft-tissue mass. Periosteal vs paraosteal OS: Parosteal OS is a densely ossified juxtacortical mass that lies outside the cortex and occurs in metaphyses whereas periosteal OS is usually more lytic in appearance, causing cortical erosion and periosteal reaction, and occurs in metadiaphyses. Periosteal vs high grade surface OS: High-grade surface OS often involves the entire circumference of the cortex and is more likely to show medullary invasion. Furthermore, the presence of a high histologic grade, identical to that of conventional OS, throughout the entire tumor is diagnostic of high-grade surface OS.
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!