Case Of the Week (COW) 14 June 2015
Small round cell tumour of the bone.
Findings:
X-Ray pelvis with both hips shows marrow expansion with permeative lytic lucencies noted involving the ilium,ischium & pubis bones on the right side. Also there is a adjacent large soft tissue component noted. Minimal periosteal reaction noted. Subcutaneous fat planes is obliterated on the right side.
MRI shows marrow infiltration with STIR hyperintensities and permeative lytic lesions involving ilium,ischium, & pubis bones on the right side with minimal periosteal reaction. There is heterogenously enhancing large adjacent soft tissue component indenting the bladder and predominantly infiltrating the obturator internus,pyriformis & gluteal muscles. Well defined lytic lesions noted in the neck and shaft of left femur suggestive of metastasis.
Discussion:
Minimal marrow infiltration with large soft tissue component-suggestive of round cell tumor,Ewing sarcoma. Histopathological examination showed fibrocollagenous tissue,areas of necrosis and fibrosis,blood clot and skeletal muscle bundles.some foci shows sheets of small round cells with scanty cytoplasm and dark staining nuclei suggestive of small round cell tumour. Ewing sarcoma is the second most common highly malignant primary bone tumour of childhood after osteosarcoma, typically arising from medullary cavity with invasion of Haversian system. They usually present as moth-eaten destructive permeative lucent lesions in the shaft of long bones with large soft tissue component without osteoid matrix, and typical onion skin periostitis. It may also involve flat bones and appears sclerotic in up to 30% of cases. Bone to bone metastasis occurs in 20% of the cases.
Plain film and CT:
The appearance of these tumours is very variable, but usually have clearly aggressive appearance. Common findings include :
- permeative: 76%
- laminated (onion skin) periosteal reaction : 57%
- sclerosis: 40%
They occasionally demonstrate other appearances, including codman triangles, spiculated (sunburst) or thick periosteal reaction and even bone
expansion or cystic components. Soft tissue calcification is uncommon, seen in less than 10% of cases.
MRI:
T1: low to intermediate signal
T1 C+ (Gd): heterogeneous but prominent enhancement
T2: heterogeneously high signal, may see hair on end low signal striations
Contributed By:
Prof. S Babu Peter
Barnard Institute of Radiology
Small round cell tumour of the bone.
Findings:
X-Ray pelvis with both hips shows marrow expansion with permeative lytic lucencies noted involving the ilium,ischium & pubis bones on the right side. Also there is a adjacent large soft tissue component noted. Minimal periosteal reaction noted. Subcutaneous fat planes is obliterated on the right side.
MRI shows marrow infiltration with STIR hyperintensities and permeative lytic lesions involving ilium,ischium, & pubis bones on the right side with minimal periosteal reaction. There is heterogenously enhancing large adjacent soft tissue component indenting the bladder and predominantly infiltrating the obturator internus,pyriformis & gluteal muscles. Well defined lytic lesions noted in the neck and shaft of left femur suggestive of metastasis.
Discussion:
Minimal marrow infiltration with large soft tissue component-suggestive of round cell tumor,Ewing sarcoma. Histopathological examination showed fibrocollagenous tissue,areas of necrosis and fibrosis,blood clot and skeletal muscle bundles.some foci shows sheets of small round cells with scanty cytoplasm and dark staining nuclei suggestive of small round cell tumour. Ewing sarcoma is the second most common highly malignant primary bone tumour of childhood after osteosarcoma, typically arising from medullary cavity with invasion of Haversian system. They usually present as moth-eaten destructive permeative lucent lesions in the shaft of long bones with large soft tissue component without osteoid matrix, and typical onion skin periostitis. It may also involve flat bones and appears sclerotic in up to 30% of cases. Bone to bone metastasis occurs in 20% of the cases.
Plain film and CT:
The appearance of these tumours is very variable, but usually have clearly aggressive appearance. Common findings include :
- permeative: 76%
- laminated (onion skin) periosteal reaction : 57%
- sclerosis: 40%
They occasionally demonstrate other appearances, including codman triangles, spiculated (sunburst) or thick periosteal reaction and even bone
expansion or cystic components. Soft tissue calcification is uncommon, seen in less than 10% of cases.
MRI:
T1: low to intermediate signal
T1 C+ (Gd): heterogeneous but prominent enhancement
T2: heterogeneously high signal, may see hair on end low signal striations
Contributed By:
Prof. S Babu Peter
Barnard Institute of Radiology