Answer for BIR CoW 28 Jan 2024
Conventional intramedullary Osteosarcoma
Findings
Evidence of ill-defined interosseous sclerotic lesion in proximal meta diaphyseal region of tibia having osteoid matrix with a wide zone of transition and permeative pattern of cortical destruction and interrupted aggressive periosteal reaction noted. Associated with subperiosteal soft tissue lesion with osteoid matrix noted in the posterior aspect of the tibia with intact posterior cortex.
Discussion
General considerations - Osteosarcoma is the most common non-hematological primary bone malignancy The second most common primary malignant bone tumour, representing 20% of all primary malignant bone tumours. Osteosarcoma can be divided into five distinct clinical types: Central osteosarcoma (conventional), (commonest) Multicentric osteosarcoma, Parosteal osteosarcoma (juxtacortical osteosarcoma), Secondary osteosarcoma, Extraosseous osteosarcoma. Central osteosarcoma (conventional) - Histo: Arising from undifferentiated mesenchymal tissue; forming fibrous I cartilaginous I osseous matrix (mostly mixed) that produces osteoid I immature bone Age: bimodal distribution 10- 25 years and >60 years; Symptoms: Painful swelling of the involved limb is a common presenting symptom, fever (frequent), Loss of weight, Cachexia Location: The metaphyses of the distal femur, proximal tibia, and proximal humerus are the most common sites. Site: origin in metaphysis (90-95%) Pathological Features - Patterns of growth : Osseous / sclerotic lesions (50 %) – increased osseous neoplastic tissue Sarcomatous / lytic lesion (25 %) – increased sarcomatous connective tissue Mixed pattern Metastases : Lung metastases – hematogenous route Presents as cannon ball metastases Results in spontaneous pneumothorax Skeletal metastases – skip lesions Lab findings : Elevated alkaline phosphatase (highest in sclerotic presentation) Radiological 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 tumour on the upper and lower margins (It is non-specific and it occurs in Osteomyelitis, Traumatic periostitis, Ewing’s sarcoma, Malignant lymphoma) Pathological fractures 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 and assisting biopsy Used to detect lytic lesions with small amounts of mineralized material MRI For accurate local staging & assessment for limb-sparing resection in intraosseous tumour extension & soft tissue involvement Evaluation of growth plate Soft tissue non-mineralized component – T1 intermediate signal intensity; T2 High signal intensity Mineralized components – T1 & T2 low signal intensity Peritumoral edema – T1 intermediate, T2 high signal intensity Bone scintigraphy Increased activity (Hotspots) at the site of primary tumour & in sites of metastasis FDG PET To detect bone metastasis Metastatic lesions will show increased SUV Also used in follow-up to evaluate response to chemotherapy
Reference - Yochum and Rowe’s – essential of skeletal radiology – third edition.
Findings
Evidence of ill-defined interosseous sclerotic lesion in proximal meta diaphyseal region of tibia having osteoid matrix with a wide zone of transition and permeative pattern of cortical destruction and interrupted aggressive periosteal reaction noted. Associated with subperiosteal soft tissue lesion with osteoid matrix noted in the posterior aspect of the tibia with intact posterior cortex.
Discussion
General considerations - Osteosarcoma is the most common non-hematological primary bone malignancy The second most common primary malignant bone tumour, representing 20% of all primary malignant bone tumours. Osteosarcoma can be divided into five distinct clinical types: Central osteosarcoma (conventional), (commonest) Multicentric osteosarcoma, Parosteal osteosarcoma (juxtacortical osteosarcoma), Secondary osteosarcoma, Extraosseous osteosarcoma. Central osteosarcoma (conventional) - Histo: Arising from undifferentiated mesenchymal tissue; forming fibrous I cartilaginous I osseous matrix (mostly mixed) that produces osteoid I immature bone Age: bimodal distribution 10- 25 years and >60 years; Symptoms: Painful swelling of the involved limb is a common presenting symptom, fever (frequent), Loss of weight, Cachexia Location: The metaphyses of the distal femur, proximal tibia, and proximal humerus are the most common sites. Site: origin in metaphysis (90-95%) Pathological Features - Patterns of growth : Osseous / sclerotic lesions (50 %) – increased osseous neoplastic tissue Sarcomatous / lytic lesion (25 %) – increased sarcomatous connective tissue Mixed pattern Metastases : Lung metastases – hematogenous route Presents as cannon ball metastases Results in spontaneous pneumothorax Skeletal metastases – skip lesions Lab findings : Elevated alkaline phosphatase (highest in sclerotic presentation) Radiological 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 tumour on the upper and lower margins (It is non-specific and it occurs in Osteomyelitis, Traumatic periostitis, Ewing’s sarcoma, Malignant lymphoma) Pathological fractures 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 and assisting biopsy Used to detect lytic lesions with small amounts of mineralized material MRI For accurate local staging & assessment for limb-sparing resection in intraosseous tumour extension & soft tissue involvement Evaluation of growth plate Soft tissue non-mineralized component – T1 intermediate signal intensity; T2 High signal intensity Mineralized components – T1 & T2 low signal intensity Peritumoral edema – T1 intermediate, T2 high signal intensity Bone scintigraphy Increased activity (Hotspots) at the site of primary tumour & in sites of metastasis FDG PET To detect bone metastasis Metastatic lesions will show increased SUV Also used in follow-up to evaluate response to chemotherapy
Reference - Yochum and Rowe’s – essential of skeletal radiology – third edition.
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
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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!