Answer for BIR CoW 25 Dec 2022
Ewing's sarcoma
Findings
Large well defined T1 isointense, T2 heterointense soft tissue periosseous lesion in medial aspect of right femur bone adjacent to midshaft displacing the muscles medially ,with adjacent focal cortical bony destruction with multiple flow voids The lesion shows diffusion restriction with significantly low ADC values. STIR hyperintensity noted in the vastus lateralis muscle Multifocal patchy T1 hypointense /T2 hyperintense bone marrow infiltration noted in greater trochanter, mid and distal shaft of femur
Discussion
Ewing sarcoma of bone represents the second most common primary malignant tumor of bone in children and adolescents. The most common affected sites are the femur (21% of cases), ilium (12%–13%), tibia (8%–11%), humerus (10%), fibula(7%–9%), ribs (8%), and sacrum (6%). The clinical presentation of Ewing sarcoma is usually nonspecific, with pain and a mass or swelling.) Fever and increased ESR simulating an infectious origin are also common. On radiography, bone destruction with a moth-eaten to permeative pattern and a wide zone of transition (poor margination) is seen. Cortical destruction with an associated soft-tissue mass is also common. Periosteal reaction is frequent and usually aggressive in appearance, either lamellated (onionskin) or spiculated (sunburst or hair-on-end). The appearance of Ewing sarcoma at CT is similar to that at radiography, with aggressive bone destruction and a large associated soft tissue mass. Contrast enhancement is common at CT and is usually either diffuse or peripheral nodular. MR imaging of Ewing sarcoma of bone reveals marrow replacement and cortical destruction, with an associated soft-tissue mass. The signal intensity is usually homogeneous (73%) and intermediate (95%) on T1-weighted images. On T2-weighted images, Ewing sarcoma is typically homogeneous (86%) and low to intermediate in signal intensity (68%). This signal intensity and homogeneity are likely related to the high degree of cellularity in Ewing sarcoma. Heterogeneity is seen in 27% of cases on T1-weighted images and 14% on T2-weighted images. High signal intensity predominates in 32% of Ewing sarcomas of bone on T2-weighted images. Heterogeneity and high signal intensity on long TR images are more common in larger lesions and represent hemorrhage or necrosis. Fluid levels may also be seen as a result of hemorrhage, although this is more common after treatment. In both CT and MR, subtle cortical involvement—with linear intermediate signal intensity channels that extend through the low signal intensity cortex, represent tumor extending along the haversian canals and neurovascular channels, and allow connection between the medullary canal and soft-tissue component—is also frequent
Findings
Large well defined T1 isointense, T2 heterointense soft tissue periosseous lesion in medial aspect of right femur bone adjacent to midshaft displacing the muscles medially ,with adjacent focal cortical bony destruction with multiple flow voids The lesion shows diffusion restriction with significantly low ADC values. STIR hyperintensity noted in the vastus lateralis muscle Multifocal patchy T1 hypointense /T2 hyperintense bone marrow infiltration noted in greater trochanter, mid and distal shaft of femur
Discussion
Ewing sarcoma of bone represents the second most common primary malignant tumor of bone in children and adolescents. The most common affected sites are the femur (21% of cases), ilium (12%–13%), tibia (8%–11%), humerus (10%), fibula(7%–9%), ribs (8%), and sacrum (6%). The clinical presentation of Ewing sarcoma is usually nonspecific, with pain and a mass or swelling.) Fever and increased ESR simulating an infectious origin are also common. On radiography, bone destruction with a moth-eaten to permeative pattern and a wide zone of transition (poor margination) is seen. Cortical destruction with an associated soft-tissue mass is also common. Periosteal reaction is frequent and usually aggressive in appearance, either lamellated (onionskin) or spiculated (sunburst or hair-on-end). The appearance of Ewing sarcoma at CT is similar to that at radiography, with aggressive bone destruction and a large associated soft tissue mass. Contrast enhancement is common at CT and is usually either diffuse or peripheral nodular. MR imaging of Ewing sarcoma of bone reveals marrow replacement and cortical destruction, with an associated soft-tissue mass. The signal intensity is usually homogeneous (73%) and intermediate (95%) on T1-weighted images. On T2-weighted images, Ewing sarcoma is typically homogeneous (86%) and low to intermediate in signal intensity (68%). This signal intensity and homogeneity are likely related to the high degree of cellularity in Ewing sarcoma. Heterogeneity is seen in 27% of cases on T1-weighted images and 14% on T2-weighted images. High signal intensity predominates in 32% of Ewing sarcomas of bone on T2-weighted images. Heterogeneity and high signal intensity on long TR images are more common in larger lesions and represent hemorrhage or necrosis. Fluid levels may also be seen as a result of hemorrhage, although this is more common after treatment. In both CT and MR, subtle cortical involvement—with linear intermediate signal intensity channels that extend through the low signal intensity cortex, represent tumor extending along the haversian canals and neurovascular channels, and allow connection between the medullary canal and soft-tissue component—is also frequent
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!