Common Pitfalls in Imaging
of Extremities Sarcoma Dr Chan Lai Peng
Senior Consultant, Department of Diagnostic Radiology, SGH
12 September 2015
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• Become familiar with the algorithm for
investigating an extremity sarcoma
• Understand the approach to analyse the
radiology images
• Be aware of some common pitfalls in imaging
Learning Objectives
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• Malignant tumour arising from “solid” connective tissues of mesenchymal origin
• 2 basic types: – Bone sarcoma
– Soft tissue sarcoma
• Less than 1% of all cancers
• Most commonly present as a painless, enlarging mass
• Majority of soft tissue masses that present to physicians are benign eg lipoma, epidermal cyst, vascular lesions
What is a sarcoma?
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• Is there a mass?
• What kind of mass is it?
– Is it a neoplasm?
• If not, what is it?
• If yes, are there imaging features to suggest a particular
diagnosis?
• Benign or malignant or can’t tell?
• Image-guided biopsy
• Staging and post treatment assessment
Role of Imaging
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Lesion Assessment
• Radiographs
• Ultrasound – cyst vs solid, vascular malformations
• MRI (Investigation of choice)
• CT scan (problem solving)
• CT Angiogram
Staging Inx:
• Bone scan
• CT Chest/Abdomen
• PET scan – role is still developing
Working up a sarcoma
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• Differentiate between bone and ST sarcoma
• Assess
– Margins
– Periosteal reaction
– Matrix
– Location
Radiographs
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Aggressive features
• Ill-defined margins
transition between
normal and abnormal
bone is hard to define,
moth-eaten
• Periosteal reaction
interrupted, irregular,
onion skin, sunburst
• Matrix
cystic, chondroid /
osteoid
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Location
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Image from www.radiologyassistant.nl
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• Are there features which suggest a more specific diagnosis? Eg: – Fat density or signal
– Chondroid tissue
– Fluid-fluid levels
• Assess extent of lesion – Bone tumour - ?skip lesions
– Soft tissue extension
– Neurovascular involvement
– Joint involvement
MRI / CT
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Case 1
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• Assess extent of
lesion
– Bone tumour - ?skip
lesions
– Soft tissue extension
– Neurovascular
involvement
– Joint involvement
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Adipocytic tumours
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Adipocytic tumours: Lipoma
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Adipocytic tumours :
Liposarcoma
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Adipocytic tumour:
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Adipocytic tumour: Myelolipoma
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Chondroid tumours
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Chondroid tumour 1
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Enchondroma
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Chondroid tumour 2
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Chondrosarcoma
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• Bigger size ( > 5 cm)
• Older patient
• Endosteal scalloping > 2/3 of the cortex
• Soft tissue mass / broken cortex / periosteal
reaction
• Increased uptake on bone scan
Features favouring chondrosarcoma
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• Bony pitfalls
– Osteonecrosis
– Stress fractures
– Paget’s disease
– Non-ossifying fibroma
• Articular/ Juxtaarticular conditions
– Ganglia, bursa, synovitis
– Tophus
• Soft tissue trauma
– Morel Lavelle
Pitfalls in imaging sarcoma
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Nonossifying Fibroma
33 Images from statdx
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Osteonecrosis and synovial
proliferation
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Gout
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Scleroderma
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Morel Lavelle
• a closed degloving
injury associated with
severe trauma which
then presents as a
haemolymphatic
mass.
• Classically occurs
over greater
trochanter
• Presents as a mass
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THANK YOU
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