Answer for BIR CoW 30 Aug 2020
Intramedullary Osteosarcoma of the Ilium
Findings
The Plain radiograph pf the Pelvis AP view shows Sclerosis of right iliac bone involving the acetabulum with sunburst type of periosteal reaction and large extraosseous soft tissue component in the lateral aspect , showing tumor new bone formation . These features are pathognomic of Osteosarcoma. MRI of the Pelvis was done and shows the following findings : Bone marrow infiltration(T2 hypointense , reflecting sclerosis )of right iliac bone and the acetabum with heterointense soft tissue intensity lesion noted in both sides of right iliac bone with adjacent surburst type of periosteal reaction and focal areas of mild restricted diffusion. The lesion infiltrates the right iliacus muscle, obtrurator internus and externus muscle and tensor fascia lata , pushing the bladder to the left and displaces the neurovascular bundle of posterior compartment to left. The lesion insinuates through the right greater and lesser sciatic notch and compresses the sciatic nerve and compressing the exiting sacral plexus.
Discussion
Osteosarcoma is a highly malignant tumor arising from primitive mesenchymal bone-forming cells. Histologic hallmark is production of malignant osteoid. It is the 2nd most common primary malignant bone tumor after Multiple myeloma Most common metastasis to the lungs through blood stream. INCIDENCE: More prevalent in males than female. Involves any age but highest occurrence in adolescence i.e. 12-25yrs. In long bones it is metaphyseal(89%)>diaphyseal(10%)>epiphyseal(1%) Skeletal distribution. Osteosarcomas can be either primary or secondary, and these have differing demographics. Primary osteosarcoma - typically occurs in young patients (10-20 years) with 75% occurring before the age of 20, because the growth centers of the bone are more active during the puberty to adolescence time period. Secondary osteosarcoma - occurs in the elderly, usually secondary to malignant degeneration of Paget's disease, extensive bone infarcts or post radiotherapy for other conditions. Location: femur: ~ 40% (especially distal femur) tibia: ~ 16% (especially proximal tibia) humerus: ~ 15% . But any bone can be involved. Secondary tumours on the other hand, have a much wider distribution largely mirroring the combined incidence of their underlying condition, and thus much have a higher incidence in flat bones, especially the pelvis (a favourite site of Paget's disease). The WHO recognized four histopathological variants of osteosarcoma. Osteoblastic variant Fibroblastic variant, Telangiectatic variant and Chondroblastic variant The current World Health Organization classification of OS of bone includes eight categories, based on pattern : conventional, telangiectatic, small cell, low-grade central, secondary, parosteal, periosteal, and high-grade surface Typical appearances of conventional high grade osteosarcoma in plain radiograph include: medullary and cortical bone destruction ,wide zone of transition, permeative or moth-eaten appearance ,aggressive periosteal reaction ( sunburst type , Codman triangle , lamellated (onionskin) reaction - less frequently seen ). soft-tissue mass with tumour new bone formation is pathognmonic . Role of MRI is essential in accurate local staging and assessment for limb sparing resection, particularly for evaluation of intraosseous tumour extension, skip lesions ,neurovascular bundle and soft-tissue involvement. Assessment of the growth plate is also essential as up to 75 - 88% of metaphyseal tumours do cross the growth plate into the epiphysis.
References
Greenspan - Orthopedic Imaging A Practical Approach Yochum and Rowe’s Essentials of skeletal radiology Imaging Characteristics of Primary Osteosarcoma: Nonconventional SubtypesGail Yarmish , Michael J. Klein, Jonathan Landa, Robert A. Lefkowitz, Sinchun Hwang ( RSNA ; Radiographics)
Findings
The Plain radiograph pf the Pelvis AP view shows Sclerosis of right iliac bone involving the acetabulum with sunburst type of periosteal reaction and large extraosseous soft tissue component in the lateral aspect , showing tumor new bone formation . These features are pathognomic of Osteosarcoma. MRI of the Pelvis was done and shows the following findings : Bone marrow infiltration(T2 hypointense , reflecting sclerosis )of right iliac bone and the acetabum with heterointense soft tissue intensity lesion noted in both sides of right iliac bone with adjacent surburst type of periosteal reaction and focal areas of mild restricted diffusion. The lesion infiltrates the right iliacus muscle, obtrurator internus and externus muscle and tensor fascia lata , pushing the bladder to the left and displaces the neurovascular bundle of posterior compartment to left. The lesion insinuates through the right greater and lesser sciatic notch and compresses the sciatic nerve and compressing the exiting sacral plexus.
Discussion
Osteosarcoma is a highly malignant tumor arising from primitive mesenchymal bone-forming cells. Histologic hallmark is production of malignant osteoid. It is the 2nd most common primary malignant bone tumor after Multiple myeloma Most common metastasis to the lungs through blood stream. INCIDENCE: More prevalent in males than female. Involves any age but highest occurrence in adolescence i.e. 12-25yrs. In long bones it is metaphyseal(89%)>diaphyseal(10%)>epiphyseal(1%) Skeletal distribution. Osteosarcomas can be either primary or secondary, and these have differing demographics. Primary osteosarcoma - typically occurs in young patients (10-20 years) with 75% occurring before the age of 20, because the growth centers of the bone are more active during the puberty to adolescence time period. Secondary osteosarcoma - occurs in the elderly, usually secondary to malignant degeneration of Paget's disease, extensive bone infarcts or post radiotherapy for other conditions. Location: femur: ~ 40% (especially distal femur) tibia: ~ 16% (especially proximal tibia) humerus: ~ 15% . But any bone can be involved. Secondary tumours on the other hand, have a much wider distribution largely mirroring the combined incidence of their underlying condition, and thus much have a higher incidence in flat bones, especially the pelvis (a favourite site of Paget's disease). The WHO recognized four histopathological variants of osteosarcoma. Osteoblastic variant Fibroblastic variant, Telangiectatic variant and Chondroblastic variant The current World Health Organization classification of OS of bone includes eight categories, based on pattern : conventional, telangiectatic, small cell, low-grade central, secondary, parosteal, periosteal, and high-grade surface Typical appearances of conventional high grade osteosarcoma in plain radiograph include: medullary and cortical bone destruction ,wide zone of transition, permeative or moth-eaten appearance ,aggressive periosteal reaction ( sunburst type , Codman triangle , lamellated (onionskin) reaction - less frequently seen ). soft-tissue mass with tumour new bone formation is pathognmonic . Role of MRI is essential in accurate local staging and assessment for limb sparing resection, particularly for evaluation of intraosseous tumour extension, skip lesions ,neurovascular bundle and soft-tissue involvement. Assessment of the growth plate is also essential as up to 75 - 88% of metaphyseal tumours do cross the growth plate into the epiphysis.
References
Greenspan - Orthopedic Imaging A Practical Approach Yochum and Rowe’s Essentials of skeletal radiology Imaging Characteristics of Primary Osteosarcoma: Nonconventional SubtypesGail Yarmish , Michael J. Klein, Jonathan Landa, Robert A. Lefkowitz, Sinchun Hwang ( RSNA ; Radiographics)
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!