Answer for BIR CoW 27 April 2025
Conventional Osteosarcoma
Findings
Evidence of well defined destructive sclerotic lesion noted in the metadiaphyseal region of proximal right fibula with osteoid matrix and soft tissue component and wide zone of transition with sunburst type of periosteal reaction and moth eaten pattern of bone destruction Features suggestive of Conventional osteosarcoma of right fibula
Discussion
Osteosarcoma is a tumor of mesenchymal origin and is the most common primary bone malignancy in children. The peak incidence of primary osteosarcoma occurs in the 2nd decade of life [the period of rapid skeletal growth].
Most common sites involved : Metaphysis of long bones [mainly distal femur, proximal tibia and proximal humerus] Seven distinct primary subtypes of osteosarcoma are recognized: Conventional Telangiectatic Low-grade central Small cell Parosteal Periosteal High-grade surface osteosarcomas Conventional osteosarcoma is the most common form [75%–80%] which originates from medullary canal. It is a high-grade tumour containing osteoblastic, chondroblastic, or fibroblastic elements and forms an osteoid matrix. Most commonly metastasizes to lung, presenting as cannon ball metastases and to the bones presenting as skip lesions.
RADIOGRAPHIC FEATURES :
Focal lesion in the metaphysis presenting as either : Mottled permeative lesion with a poorly defined zone of transition Dense ivory or sclerotic region filling the medullary space Cortical disruption Periosteal reaction : Sunburst Periosteal reaction - Periosteal new bone formation within an extracortical dense soft tissue mass producing transverse spicules or radiating striations Codman’s reactive triangles – Periosteum elevated by the tumor on the upper and lower margins (It is non-specific and it occurs in Osteomyelitis, Traumatic periostitis, Ewing’s sarcoma, Malignant lymphoma) Cumulus cloud appearance – Roughened lobulated margins seen in sclerotic lesions Soft tissue mass is common and can grow to large dimensions with ossifications within the mass CT mainly used for staging, in assisting biopsy and to detect lytic lesions with small amounts of mineralized material MRI for accurate local staging, in intraosseous tumor extension, soft tissue involvement, evaluation of growth plate and to detect skip lesions. Soft tissue non-mineralized component appears as T1 intermediate signal intensity and T2 High signal intensity lesion.Mineralized components show T1 & T2 low signal intensity while peritumoral edema shows T1 intermediate, T2 high signal intensity. Bone scintigraphy shows increased activity (Hotspots) at the site of primary tumor & in sites of metastasis FDG PET to detect bone metastasis [increased SUV values] and also used in follow up to evaluate response to chemotherapy
References : https://radiopaedia.org/articles/osteosarcoma https://doi.org/10.1148/rg.306105524
Findings
Evidence of well defined destructive sclerotic lesion noted in the metadiaphyseal region of proximal right fibula with osteoid matrix and soft tissue component and wide zone of transition with sunburst type of periosteal reaction and moth eaten pattern of bone destruction Features suggestive of Conventional osteosarcoma of right fibula
Discussion
Osteosarcoma is a tumor of mesenchymal origin and is the most common primary bone malignancy in children. The peak incidence of primary osteosarcoma occurs in the 2nd decade of life [the period of rapid skeletal growth].
Most common sites involved : Metaphysis of long bones [mainly distal femur, proximal tibia and proximal humerus] Seven distinct primary subtypes of osteosarcoma are recognized: Conventional Telangiectatic Low-grade central Small cell Parosteal Periosteal High-grade surface osteosarcomas Conventional osteosarcoma is the most common form [75%–80%] which originates from medullary canal. It is a high-grade tumour containing osteoblastic, chondroblastic, or fibroblastic elements and forms an osteoid matrix. Most commonly metastasizes to lung, presenting as cannon ball metastases and to the bones presenting as skip lesions.
RADIOGRAPHIC FEATURES :
Focal lesion in the metaphysis presenting as either : Mottled permeative lesion with a poorly defined zone of transition Dense ivory or sclerotic region filling the medullary space Cortical disruption Periosteal reaction : Sunburst Periosteal reaction - Periosteal new bone formation within an extracortical dense soft tissue mass producing transverse spicules or radiating striations Codman’s reactive triangles – Periosteum elevated by the tumor on the upper and lower margins (It is non-specific and it occurs in Osteomyelitis, Traumatic periostitis, Ewing’s sarcoma, Malignant lymphoma) Cumulus cloud appearance – Roughened lobulated margins seen in sclerotic lesions Soft tissue mass is common and can grow to large dimensions with ossifications within the mass CT mainly used for staging, in assisting biopsy and to detect lytic lesions with small amounts of mineralized material MRI for accurate local staging, in intraosseous tumor extension, soft tissue involvement, evaluation of growth plate and to detect skip lesions. Soft tissue non-mineralized component appears as T1 intermediate signal intensity and T2 High signal intensity lesion.Mineralized components show T1 & T2 low signal intensity while peritumoral edema shows T1 intermediate, T2 high signal intensity. Bone scintigraphy shows increased activity (Hotspots) at the site of primary tumor & in sites of metastasis FDG PET to detect bone metastasis [increased SUV values] and also used in follow up to evaluate response to chemotherapy
References : https://radiopaedia.org/articles/osteosarcoma https://doi.org/10.1148/rg.306105524
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!