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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