osteosarcoma ra

7/31/2019 Osteosarcoma RA

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Osteosarcoma

Key facts

Most common primarymalignant bone tumor.

50% around the knee. Presentation: pain, mass,

pathologic fracture.

Sclerosis is present from eithertumor new bone formation or

reactive sclerosis.

Plain films typically reveallesions with moth-eaten or

permeative pattern of the

transition zone with irregular

cortical destruction and aninterrupted periosteal reaction

with soft tissue extension.

A periosteal reaction known asCodman's triangle appears astumor elevates periosteum from

underlying bone. Cortical soft

tissue extension may produceradiating spicules of bone

called sunray appearance.

Osteosarcoma (osteogenic

sarcoma) is the 2nd most

common primary bone tumorand is highly malignant. It is

most common among people

aged 10 to 25, although it canoccur at any age. Osteosarcoma

produces malignant osteoid

(immature bone) from tumor

bone cells. The bone formationdictates the radiographic

pictures. When abudant bony

tumor matrix is lacking, the

osteosarcoma may be of thetelangiectatic subtype (which

sometimes may mimic

aneurysmal bone cyst!), or thedifferential diagnosis includes

Ewings sarcoma or lymphoma,

particularly when a large softtissue mass is present. In older
http://www.radiologyassistant.nl/images/4bc9ab6979b6eOS-tibia.jpg


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patients, also chondrosarcoma

can be in the differentialdiagnosis. Osteosarcoma

usually develops around the

knee (distal femur more often

than proximal tibia) or in otherlong bones (like proximal

humerus), particularly the

metaphyseal-diaphyseal area,and may metastasize, usually to

lung or other bones. Pain and

swelling are the usualsymptoms. Findings on

imaging studies vary and may

include sclerotic and/or lytic

features. Diagnosis requires

biopsy, which shoud always beperformed after imaging

Patients need a chest x-ray andCT to rule out or detect lung

metastases and a bone scan to

detect bone metastases. MR

imaging is the optimalmodality for loco-regional

staging. An imaging protocol

should at least include T1-weighted TSE series in two

perpendicular directions for

assessment of the intraosseous

extent and relationship tojoint(s) nearby, and axial T2-

WI with FS, for assessment of

the soft-tissue extension andrelationship to important

neurovascular structures.

Longitudinal imaging of anentire long bone is strongly

advocated to rule skip

metastases. After

administratipn of i.v. contrast,T1-weighted series are repeated

in two directions with FS.

Treatment is a combination of

chemotherapy and surgery. Useof (neo-)adjuvant

chemotherapy increases


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survival from < 20% to > 65%

at 5 yr. Chemotherapy usuallybegins before any surgery. The

goal of neoadjuvant

chemotherapy is to eliminate

occult distant micrometastases,and to cause tumor volume

reduction, in order to make

limb-salvage surgery possible.As such, more than 80% of

patients can be treated with

limb-sparing surgery withoutdecreasing long-term survival

rate. The role of imaging

during and after neoadjuvant

chemotherapy is to assess the

rate of response. IN particular,significant reduction of tumor

vascularization and perfusion isa strong indicator of good

response. Increase in tumor

volume strongly suggests poor

response, however, volumedecrease does not necessarily

indicate favourable response.

Continuation of (adjuvant)chemotherapy after surgery is

usually necessary. If there is

nearly complete tumor necrosis

(about 99%) from preoperativechemotherapy, 5-yr survival

rate is > 90%. Low-grade

intraosseous osteosarcoma is avery rare variant of

osteosarcoma,which may

however have a benignradiographic appearance and

therefore can be confused with,

for instance,, fibrous dysplasia.

Surface osteosarcomas havetheir origin on the surface of

bone and grow primarily into

the surrounding soft tissues, but

may also infiltrate into the bonemarrow. Among these, the

parosteal (or juxtacortical)


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osteosarcoma is the most

frequently encountered variant,most commonly on the

posterior side of the distal

meta-diaphysis of the femur.

Osteosarcoma (2)On the left images of an osteosarcoma

in the right femur.

It is barely visible, but an agressiveperiostitis is seen (arrow).

Continue with the MR-images.

Sagittal T1W- and Gd-enhanced T1W-image with fatsat.

The MR images show a large tumormass infiltrating a large portion of the

distal femur and extending through the

cortex.

Paget disease

Stress fractures
http://www.radiologyassistant.nl/images/4bc9aba21a7afOS-periost-2-MR.jpghttp://www.radiologyassistant.nl/images/4bc9ab89be96aOS-periost.jpghttp://www.radiologyassistant.nl/images/4bc9aba21a7afOS-periost-2-MR.jpghttp://www.radiologyassistant.nl/images/4bc9ab89be96aOS-periost.jpg


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Stress fractures occur in normal

(fatigue fractures) or metabolicallyweakened (insufficiency fractures)

bones. Usually stress fractures are easy

to recognize ...... Uncommonly it can

be difficult to differentiate a stressfracture from a pathologic fracture,

that occurs at the site of a bone tumor

(7).

Osteoid osteoma versus stress fracture

Uncommonly it can be difficult to

differentiate a stress fracture from apathologic fracture, that occurs at the

site of a bone tumor (7).

Follow up images of stress fracture in medial collum

Stress fractures
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osteosarcoma ra

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