K E Y P O I N T S Primary bone tumors are rare;non-neoplastic
conditions, metastatic disease, and lymphohematologic malignancies, which may simulate primary bone tumors, by far outnumber genuine bone tumors.
Excluding myeloma and lymphoma, malignant primary bone tumors constitute only 0.2% of all malignancies in adults and approximately 5% of childhood malignancies.
Epidemiology The vast majority of primary bone tumors are benign
and since many are non-symptomatic they remain undetected or are detected only incidentally at radiographic examinations for other reasons. The true incidence of benign bone tumors has therefore been difficult to determine.
The incidence of primary bone malignancies is in contrast, fairly well documented in various national cancer registries
Primary bone malignancy Frequency (%)
Ewing’s sarcoma 16.0
Malignant fibrous histiocytoma 5.7
Classification of primary benign bone tumors, peak age, and most common sites distribution
The histologic classification of bone tumors is based on cytologic findings (in particular cell type such as osteocyte/osteoblast, chondrocyte/chondroblast, osteoclast,etc.), architecture, and type of matrix produced by the tumor.
Despite the rarity of bone tumors there is a very wide spectrum of entities with sometimes overlapping features; the current WHO classification (2002) includes a total of 45 main bone tumor types.
Histologic type Peak age (years) Most common sites
Osteochondroma 10–30 Distal femur, proximal tibia,proximal humerus, rarely fromflat bone
Enchondroma 10–40 Hands, feet, long tubular bones
Periosteal chondroma 10–40 Proximal humerus, distal femur,hip region, and pelvis
Chondroblastoma 10–30 Distal femur, proximal tibia and humerus,calcaneus
Principles of Detection and Diagnosis The majority of bone tumours are detected using
Occasionally occult lesions may be detected using more sensitive techniques such as bone scintigraphy and MR imaging
Careful analysis of the pattern of bone destruction, periosteal reaction and matrix mineralisation on radiographs allow for characterisation of many bone tumours.
Additional factors that should be included in determining the likely diagnosis include the age of the patient, location of the tumour in bone and any history of a pre-existing bone abnormality, e. g. Paget’s disease
Diagnosis Before assessing the imaging the prudent radiologist
should establish some basic facts regarding the patient
Ethnic and geographic origin.
Past medical history
Age. The age of the patient is arguably the single most
useful piece of information as it frequently influences the differential diagnosis
Many musculoskeletal neoplasms exhibit a peak incidence at different ages
Jack Edeiken(skeletal radiologist), reasonably claimed that approximately 80% of bone tumours could be correctly diagnosed on the basis of age alone.
Ages 0 10 20 30 40 50 60 70
Simple bone cyst
Fibrous cortical defect
Aneurysmal bone cyst
0 10 20 30 40 50 60 70
Giant cell tumor
Malignant fibrous histiocytoma
Gender. In the individual case gender does not play a
significant role in formulating the differential diagnosis
When looking at large series of patients with different types of bone tumor it can be seen that many occur slightly more commonly in boys.
Ethnic and geographic origin Ewing’s sarcoma is prevalent in Caucasians but is
rarely seen in the Afro -Caribbean races
Non-neoplastic bone conditions that may on occasion simulate neoplasia also show a racial predisposition, e.g. sickle cell,Gaucher’s and Paget’s diseases
Osseous TB can mimic a bone tumour and is seen commonly in developing countries
Family history Little evidence of a familial predisposition to the
formation of musculoskeletal neoplasms in most instances.
The exceptions are certain hereditary bone conditions that may be found in association with malignant change,inlude:
Ollier’s disease and Mafucci’s syndrome
Serology. Abnormal serological tests, such as raised erythrocyte
sedimentation rate (ESR) and white cell count, together with the examination findings of a hot swollen limb, are highly suggestive of a bone or so tissue infection. Ewing’s sarcoma, however ,is notorious for presenting with similar clinical and serological findings.
The brown tumor of hyperparathyroidism may mimic a true bone tumor on both imaging and histology. Raised serum calcium and alkaline phosphatase levels should alert the clinician to the possibility of this diagnosis.
Raised prostatic serum antigen level in an elderly male patient presenting with a bone-forming tumour is highly suggestive of a prostate metastasis.
Radiographic DiagnosisThe radiograph remains the most
accurate of all the imaging techniques currently available in determining the differential diagnosis of a bone lesion.
“Aunt Minnie approach”
“Aunt Minnie approach”. This epithet was attributed by the late Ben Felson to Ed
Neuhauser, Chief of Radiology at the Boston Children’s Hospital over half a century ago.
It consists of a question and answer:
Q:“How do you know that woman is your Aunt Minnie?”
A: “Because I’ve seen her before and it looks like her”
This approach relies on familiarity with the typical overall appearances of a particular lesion.
This is all very satisfactory if the abnormality under investigation is classic in appearance, but problems arise if the lesion has atypical features, arises at an unusual site or is mimicked by a differing pathology.
Pattern analysis Relies on meticulous recognition of various
Analysis can be best illustrated by answering a series of five questions:
Which bone is affected?
Where in that bone is the lesion located?
What is the tumour doing to the bone (pattern of destruction)?
What form of periosteal reaction, if any, is present?
What type of matrix mineralisation, if any, is present?
Site in Skeleton
Most bone tumours and infections occur around the knee and in the proximal humerus, and as such, little diagnostic information can be deduced from noting the affected bone in many cases.
Benign cartilagenous tumors: hands and feet
Osteo fibrous dysplasia and adamantinoma : classically involve the diaphysis of the tibia and are extremely rare at any other site
Medial third of the clavicle in children and adolescents: osteomyelitis or part of the spectrum of chronic recurrent multifocal osteomyelitis.
•Most lesions arising in the sternum are malignant• Chordoma characteristically arises from the clivusor sacrum.•Many different tumours may arise in the bony spine, malignant lesions are found predominantly in the anterior part of the vertebra (body), while benign lesions, with a few exceptions, are characteristically found in the posterior elements•Most spinal infections develop first in the vertebral endplate and rapidly extend to involve the disc space, which is uncommon in neoplasia.
Osteobrousdysplasia (OFD) tibiaLateral radiograph shows a typical mildly expansile lytic lesion arising in the
anterior cortex of the diaphysis. This is the typical site for OFD
and adamantinoma; both are rare at other skeletal sites
Location in Bone The site of the original bone tumour is an important
parameter of diagnosis. It reflects the site of greatest cellular activity.
During the adolescent growth spurt the most active areas are the metaphyses around the knee and the proximal humerus.
Tumour originating from marrow cells may occur anywhere along the bone
Conventional osteosarcoma will tend, therefore, to originate in the metaphysis or meta-diaphysis
Lateral radiograph shows some ill-defined
sclerosis in the distal femoral metaphysis due to malignant osteoid.
Ewing’s sarcoma willarise in the metaphysisor, more distinctively, in the diaphysis
in the femur. AP radiograph
shows the classical diaphyseal location,.
In the child the differential diagnosis of a lesion arising within an epiphysis can be realistically limited to: 1.Chondroblastoma2. epiphyseal abscess (pyogenic or tuberculous) and3. Langerhans cell histiocytosis
Following skeletal fusion subarticular lesions, analogous in the adult to the epiphyseal lesions in children, include:1. giant cell tumour2.clear cell chondrosarcoma (rare)3. intraosseous ganglion
With the exception of epiphyseal abscess most osteomyelitiswill arise within the metaphysis of a long bone, typically the tibia and femur.
Chondroblastoma tibia. a AP radiograph shows a lytic lesionarising in the proximal tibial epiphysis.
Location in BoneIt is also helpful to identify the origin
or epicentre of the tumour with respect to the transverse plane of the bone.
central simple bone cyst,
Fibrous dysplasia tibia. AP radiograph shows typical features being well defined and central, mildly expansile with a ground-glass density matrix
eccentric Giant cell tumour
Chondro myxoid fibroma
AP radiograph shows a lytic, eccentric, subarticular lesion
Non-ossifying fibroma tibia
AP radiograph shows a typical
example with a well-defined sclerotic margin arising in an eccentric location complicated by a pathological fracture
High grade surface
and Parosteal osteosarcoma
summary Analysis of the location of a tumour in bone should,
therefore, recognize the position in both the longitudinal and transverse planes.
Combining these factors can then help to narrow down the differential diagnosis.
A Giant cell tumour will be subarticular and eccentric, whereas both non-ossifying fibroma and chondromyxoidfibroma will tend to be metaphyseal and eccentric in location
In the sacrum, chordoma classically arises in the midline, whereas giant cell tumour, a not uncommon tumour in the sacrum at a similar age, will be eccentric bordering on one of the sacroiliac joints, i.e. subarticular in origin.
The typical sites of bone tumours. MFH malignant
broushistiocytoma, ABC aneurysmalbone cyst
Pattern of Bone Destruction Bone destruction is usually the first radiographic sign of disease and may
be the only evidence of pathology.
Trabecular bone is more easily destroyed than cortical bone. As individual trabeculae contribute less to the overall radiographic image, relatively large amounts of spongy bone must be destroyed before it is visible
Analysis of the interface between tumour and host bone is a good indicator of the rate of growth in the lesion.
A sharply marginated lesion usually denotes slower growth than a non-marginated lesion.
The faster the growth, the more “aggressive” the pattern of destruction and the wider the zone of transition between tumour and the normal bone
Aggressivity, per se, does not conclusively indicate malignancy,but the malignant tumours tend to be faster growing than their benign counterparts.
The American skeletal radiologist, GwilymLodwick, described three patterns of bone destruction associated with tumours and tumour-like lesions of bone:
type 1, geographic bone destruction
type 2, moth-eaten bone destruction
type 3, permeative bone destruction
Type 1: Geographic In this pattern the growth rate is sufficiently
indolent and the lesion will appear well marginated with a thin zone of transition.
The geographic pattern may be further subdivided into 3 types depending on the appearance of the margin and the effect on the cortex
Type 1A The slowest growing of all the lesions and thereby the
least aggressive, is characterized by a sclerotic margin.
The thicker the sclerotic rim, the longer the host bone has had time to respond to the lesions indicating a slow rate of growth
The vast majority of these lesions will prove to be benign
Type 1B The lesion is well defined without the sclerotic margin.
While still relatively slow growing, the rate is slightly greater than that of type 1A. Again, the majority of type-1B lesions are benign, although some malignancies may on occasion demonstrate this pattern.
Type 1C Margin is less well defined, indicating a more
cortex is also destroyed.
Few benign tumours exhibit a type-1C pattern.
The differential diagnosis in this situation includes giant cell tumour, malignant fibrous histiocytoma and lymphoma of bone
Type 2 : Moth-eaten; Type 3 : Permeative Moth-eaten and permeative patterns of bone
destruction reflect the increasingly aggressive nature of these tumours compared with geographic lesions
This is a spectrum of change varying from multiple foci of bone destruction which may coalesce (moth-eaten) to multiple tiny defects, best seen in the cortical bone, which gradually diminish in size and frequency from the centre to periphery of the lesion (permeative) resulting in an ill-defined wide zone of transition
Ewing’s sarcoma in the humerus. AP radiograph and magnified detail show a highly aggressive permeativepattern of bone destruction
Ewing’s sarcoma and
Benign tumours in general do not show this pattern of bone destruction.
Acute osteomyelitis may also give a motheaten pattern of bone destruction.
spiculated (“hair-on-end”) periosteal reaction This occurs when the mineralisation is oriented
perpendicular to the cortex and denotes a more rapidly evolving process:
Typical of malignant tumors:
Osteosarcoma and Ewings sarcoma
May be seen in benign tumours including meningioma, haemangioma of bone and non-neoplastic conditions such as thalassemia and thyroid acropachy.
Periosteal osteosarcoma in the tibiaAP radiograph shows a spiculated periostealreaction arising from the
medial aspect of the proximal diaphysis. obliquity of the spicules at the periphery of the lesion means that the pattern
could also be described as “sun-ray” or “sun-burst”
DiscontinuousPeriosteal Reaction A discontinuous or interrupted periosteal reaction indicates that the
mineralisation has been breached in one of two ways:
Either the process, usually a tumour, simply occupies the available space,
or the rate of apposition of new bone is exceeded by the rate of resorption.
In malignant bone tumours the site of interruption of a periostealreaction is usually the area of maximum extra-osseous tumour growth.
The periosteal reaction forms an angular configuration with the underlying cortex, resembling two sides of an angle and indicates an aggressive pathology.
This is formed by the elevation of periosteum by tumor, blood,edemaor pus
Angle may or may not contain tumor
Buttresses In this type the solid reactive
bone is formed at the lateral extra osseous margin of slow growing bone lesions, the cortex beneath the buttress Is frequently intact.
CombinedPeriosteal Reaction More than one pattern of periosteal reaction may be
manifest in the same case and is called a combined or complex pattern. This reflects the varying rate of growth at different sites in the same lesion.
The divergent spiculated periosteal reaction, otherwise known as “sun-burst” or “sun-ray”, is a typical example of a complex pattern and is suggestive of osteosarcoma
AP radiograph shows all the
typical features of the tumoursincluding permeative bone de-
struction, malignant osteoidmineralisation and a complex periostealreaction
Tumour Mineralisation Tumour new bone is the matrix of intercellular substance
produced by certain tumour cells that can calcify or ossify.
Radiodense tumour matrix is of either osteoid (osteogenictumours) or chondroid (chondrogenic tumours) origin.
Tumour osteoid is typied by
solid (sharp-edged) or
cloud to ivory-like
Tumour cartilage is variously described as
ring and arc and
popcorn in appearance
Identifying the pattern of matrix calcification will signicantly reduce the differential diagnosis, but matrix per se has no influence as to whether the lesion is benign or malignant, just whether the tumour is of osteogenic or chondrogenic origin.
Enchondroma: Radiographs show dense chondrogenic calcications in the form ofrings and arcs in the proximal metadiaphyseal humerus. underlying osteolysis is completelyobscured by the calcifications. There is no sclerotic rim and the cortex is intact.
Radiographic appearance of osteoid matrix in osteosarcoma. a Lateral radiograph of thedistal femur shows predominantly fluffy osteoid matrix (asterisk) in bone and within the large so tissue component. b Anterioposterior radiograph shows a predominantly cloudlike (cumulous) opacity (asterisk) in the proximal humerus and adjacent so tissue
Well defined sclerotic borders
Geographic pattern of bone destruction
Continous solid periostealreaction
No soft tissue extension
Poorly defined margins with wide zone of transition
Moth-eaten or permeativepattern of bone destruction
An interrupted periostealreaction of the sunburst or onion skin type
Adjacent soft tissue mass
ROLE OF CT CT has complementary role in the diagnosis and local staging of bone
Custom prosthesis production
Percutaneous treatment guidance
Scanning the chest for detection of pulmonary metastases is primary role for CT
CT remains essential for patients in whom MR is contraindicated
CT provides greater morphological detail about the bone surrounding lesion and analysis can be applied in the same way as classic radiographic margin analysis.
CT is typically used in order to obtain radiographic information where conventional radiograph fail due to limited contrast resolution, complex anatomy e.g. spine, pelvis or scapula
Most important advantage of CT over radiography is its superior delineation of cortical alterations, of which cortical expansion and remodelling, endosteal scalloping and focal penetration represent the most common form in benign bone lesion
CT has the ability to depict periosteal reaction that might be invisible on radiograph .
Subtle matrix calcifications
Intraosseous tumors are well demonstrated
CT of the knee, windowed forsoft tissues and bone, demonstrates subtle periosteal reactionof the lateral tibia and an adjacent so tissue mass (arrows).
Juxtacortical chondroma: Radiographs and computed tomography show a saucer-like juxtacortical lesion separated by a thick sclerotic rim from the medullary cavity
Osteoma of the skull in a 40-year-old woman with 12 year history of a “hard” mass. a Townes view of the skull shows the osteoma (arrows) as a dense osseous mass arising from the outer table of the skull. b Axial noncontrast CT displayed on bone window shows the lobulated mass (arrows) arising from the outer table. e mass images similar to the adjacent cortical bone
Osteoblastoma of the lumbar spine. a Anteroposterior radiograph of the lumbar spine shows a lesion in the posterior elements of L4 (white asterisk) with prominent sclerosis (black asterisk). b Axial noncontrast CT scan shows the lesion (white asterisk) with subtle mineralized matrix, moderate expansile remodeling and prominent sclerosis (black asterisk)
Osteoblastoma of the femur. a Anteroposterior radiograph of the proximal femur shows a geographic lytic lesion (asterisk) with solid continuous periosteal new bone (arrow) distant from the lesion. b Axial noncontrast CT scan shows the lesion with prominent mineralized matrix and associated sclerosis
Anteroposterior radiograph of the wrist shows a densely sclerotic mass with prominent expansile remodeling (arrows). b Surface rendered 3-DCT scan shows the expansile remodeling of the mass to better advantage. Reformatted coronal CT displayed at bone window
Computed tomography in acoronal reconstruction shows a well-demarcated lytic lesion inthe proximal epimetaphyseal femur, one of the less frequentlocations of chondroblastoma. ere is an incomplete thin rimof sclerosis and the cortex is partially destroyed.
Role of MRI MRI is the best imaging modality in assessing:
Intra and extra compartmental extent
Neuro vascular and juxta articular involvement
Images should be obtained with the smallest practical FOV in order to maximize image detail, while performing the entire study in a clinically practical time period
T1-weighted spin-echo images are particularly important in the evaluation of bone marrow, whereas intermediate-weighted images should be avoided.
Fat suppression must be applied when obtaining T2-weighted fast spin-echo images to demarcate tumor from surrounding bone marrow and edema.
Administration of a gadolinium-chelate contrast material can provide useful information in characterization of bone lesions, as well as in assessment of response to therapy and detection of recurrent tumor.
Imaging protocol T1-weighted SE
T2-weighted Fast SE
STIR Short-tau inversion recovery (STIR) frequently is used as an
alternative fat-suppression sequence to achieve homogeneous fat suppression and T2-weighting, particularly in situations where fat suppression with T2 weighted fast SE would be unsatisfactory
Primary lymphoma of humerus. a Coronal T1-weighted SE image shows that signal intensity of tumor (T) in medullary cavity is low, similar to that of muscle (asterisk). b Coronal short-tau inversion recovery (STIR) image demonstrates diffusely high signal intensity both within the tumor (T) and throughout extensive surrounding edema (arrows). Note that margins of tumor cannot be visualized in b
Importance of fat suppression for lesion evaluation at T2-weighted fast SE imaging. a In coronal T2-weighted fast SE without fat suppression, the lesion (arrows) in distal tibia has high signal intensity similar to that of normal marrow (asterisk), and its border is poorly dened. b T2-weighted fast SE image with fat suppression clearly demonstrates margins of the lesion (arrows), and also clearly demonstrates very high signal within multiple lobules,consistent with a chondroid lesion
Lesion conspicuity in gadolinium-enhanced images with and without fat suppression.a Gadolinium-enhanced transverse T1-weighted SE image obtained without fat suppression shows subtle mild peripheral contrast enhancement (arrows) of the lesion in proximal femur. Peripheral high signal (arrowheads) due to chemical shi artifact partly obscures the border of the lesion. b Sub-sequent image obtained with same parameters and fat suppression reveals more peripheral (arrows) and nodular (arrowhead) regions of enhancement. e previous chemical shift artifact is no longer present. Biopsy revealed liposclerosing myxobrous tumor
Calcication demonstrated on T2*-weighted GE image. a Transverse T2*-weighted GE image(TE=24 ms) shows several small signal voids (arrowheads) within a low-grade chondrosarcoma in distal femur.b Anteroposterior radiograph of the knee demonstrates faint foci of calcication(arrowheads) in distal femur, corresponding to the signal voids seen in GE image
Nonspecic signal intensity of tumor on STIR sequence. On a coronal T2-weighted SE image without fat suppression, diffusely low signal intensity throughout the giant celltumor (T) suggests chronic internal hemorrhage. On b coronal STIR image, tumor (T) is diffusely very high in signal intensity, which improves conspicuity of the tumor but diminishes the ability to characterize it
Skip lesions of osteogenic sarcoma in le femur.Coronal T1-weighted SE image reveals skip (metastatic) lesions in
the proximal diaphysisand distal epiphysis of femur (arrows),
in addition to the primary tumor (T) in distal metaphysis
Diffusion-weighted imaging (DWI) in Ewingsarcoma of tibia. a Transverse T2-weighted SE image with fatsuppression shows extensive high signal in the tumor (T) andits subperiosteal component (arrows), as well as in surroundingso tissue edema (arrowheads). b Transverse DWI (b=1000)allows differentiation of tumor (T) from surrounding edema bydemonstrating increased signal in the tumor (arrows) but notin surrounding edema
Fluid-like intensity within enchondroma. Transverse T2-weighted SE image with fat suppression demonstratesa medullary lesion in humeral head consisting of multiple smallchondroid lobules with very high signal intensity (arrows)
Fluid-fluid levels in aneurysmal bone cyst. Trans-verse T2-weighted SE image with fat suppression demonstrates an expansile lesion consisting solely of multiple .fluid-fluid levels (arrows) in proximal tibia. e rather low signal intensity of the dependent portions of the levels is compatible with old blood products
Edema around bone tumors. a Coronal T2-weighted SE image with fat suppression demonstrates a lesion(T) with high signal intensity in the humeral head. Bone marrow edema (arrows) throughout the proximal humerus is sub-stantially larger in extent than the lesion (chondroblastoma)itself. Moderate joint eusion (asterisk) is present
Necrosis in poorly differentiated carcinoma in humerus. Coronal post-gadolinium-enhanced T1-weighted SEimage with fat suppression demonstrates relatively little enhancement in tumor (T), and poorly defined enhancement insurrounding edematous region. Gross pathologic examinationrevealed extensive necrosis and hemorrhage
sagittal T1-weighted image and heterogeneous and moderately hyperintense on c sagittal T2-weighted image with fat suppression. d Sagittal T1-weight-ed contrast-enhanced, fat-suppressed image shows extensivelyincreased signal indicating a predominantly solid, not cystic, tumour
Coronal post-contrast T1W SE MR image shows the intramedullarytumour extent, which does not reach the distal femoral articularsurface (arrows)
Proximal tibial osteosarcoma with joint involvement. Coronal PDW FSE MR image shows tumour in theproximal tibia extending into the ACL (arrow) and also surrounding the lateral meniscus (arrowhead)
A 21-year-old male with Ewing sarcoma primary to the le iliac bone SagittalT1-weighted gadolinium-enhanced fat-suppressed images reveal innumerable enhancing metastases throughout the thoracic (a)and lumbar (b) spines (arrows)
Chondroblastoma: Anteroposterior radiograph (a) shows a lytic lesion in the proximal epiphyseal humerus with slight extension into the metaphysis. The pattern of destruction is geographic. The subchondral bone lamella is destroyed. There is considerable metaphyseal sclerosis and periosteal reaction. T1-weighted MR images without (b) andwith (c) contrast enhancement show the demarcation of the lesion and the slight extension into the metaphysis
Enostosis of the L3 vertebral body. a Lateral radiograph of the spine shows a rounded sclerotic lesion having the typical radiographic features of an enostosis (asterisk)with a radiating, spiculated border. Sagittal T1-weighted spin-echo MR images of the lesion (asterisk) show a signal intensity similar to that of cortical bone with radiat-ing speculated margin. Note peripheral location of the lesion.
Intracortical osteoid osteoma of the humerus in a 28-year-old man. a Axial noncontrast CTof the proximal humerus shows the lesion (arrow) centered within the cortex. b Coronal T2-weighted SE MR image shows the lesion (arrow) within the cortex with associated marrow edema (asterisk)
Role of USG Ultrasound can be used to assess subperiostealor
extraosseous bone tumour extension.
Ultrasound can accurately assess the cartilage cap of an osteochondroma
Bone tumours are frequently amenable to sonographically guided core needle biopsy with excellent results.
Ultrasound can prove useful in the detection oflocaltumour recurrence, especially in the presence of an endoprosthetic replacement.
Ultrasound may have a future role in the assessment of tumour response to neoadjuvant chemotherapy.
Imaging Features of Bone Tumourson Ultrasound The normal cortex of a long bone is seen as a thin
hyperechoic line which produces posterior acoustic shadowing
Ultrasound should be used to assess the integrity of the cortex, with the bone being scanned in the longitudinal and transverse planes.
Colour Doppler should also be routinely used to assess areas of tumour neovascularity and to identify tumourrelationship to any adjacent neurovascular structures
a Longitudinal and b transverse images of the mid-humerus show the hyperechoicthin line of the bone cortex (arrows) and the deep fascia (arrowheads), between which lies the muscle compartment.
Transverse Doppler US through the forearm
in a patient with Ewing sarcoma of the proxiaml radius
demonstrates the eroded radial cortex (short arrow), the
extraosseous tumour mass (arrowheads) and the adja-
cent brachial vessels (double-headed arrow)
Morphological Features of Bone Tumours on Ultrasound Cortex
Ultrasound can demonstrate an intact underlying cortex where a lesion is arising in a juxtacortical location and is not involving the bone itself
Pathological fractures are seen as a discontinuity and step of the normal hyperechoic linear cortical line, which can also be associated with an extraosseous extension of the tumour mass.
Cortical destruction from primary intramedullary tumours, particularly osteosarcoma and Ewing sarcoma, appears as a discontinuity or marked irregularity of the smooth hyperechoicline of the normal cortex, with the associated extraosseoustumour mass
Longitudinal US of the humerus in a woman
with a periosteal chondroma shows the tumour mass (ar-
rowheads) and the intact underlying cortex (arrows)
Longitudinal US of the femur in a child with osteosar-
coma shows irregular discontinuity of the femoral cortex (arrows)
with an associated extraosseous mass (arrowheads)
Periosteum Ultrasound can demonstrate the unmineralised
periosteum as a thin, hyperechoic line overlying the extraosseous tumour mass
A multilaminated periosteal reaction may be seen as multiple thin hyperechoic lines
A Codman’s triangle seen on plain radiographs manifests as a smooth angulation of the cortex at the tumour margin
Periosteal response. a Longitudinal US through the upper forearm in a child with a proximal radial Ewing sarcoma shows the tumour mass extending through the permeated cortex (arrows) and covered by the intact periosteum (arrowheads). b Longitudinal US in a child with adistal femoral osteosarcoma shows a Codman’s triangle (arrows) at the site of extraosseous tumour extension (arrowhead)
Neurovascular Bundle Ultrasound can demonstrate displacement or
encasement of the neurovascular bundle
useful in assessing flow within the vessels and ensuring that biopsy approaches are remote from the neurovascular bundle, which can sometimes be difficult to appreciate with CT-guided biopsy.
Longitudinal US through the arm in a patient
with lymphoma of the humerus shows a large soft tis-
sue mass extending from the bone surface (arrows) and
displacing and partially encasing the brachial artery
Osteosarcoma. a Transverse US through the femur (arrow) shows an extraosseousmass (arrowheads) containing heterogeneous hyerechoicareas due to matrix ossifcation. b Axialfat-suppressed, proton-density-weighted, fast spin-echo (PDW FSE) MR image
Transverse US show multiple fluid levels (arrowheads). d Longitudinal colourDoppler US shows marked neovascu-larity within th extraosseous mass (arrows)
Longitudinal US of the rib shows a sessile osteochondroma (arrows)with a small overlying hypoechoic cap (arrowhead). Peripheral chondrosarcoma. b Anteroposterior radio- graph of the ankle shows a sessile osteochondroma (arrows) of the fibula. c Longitudinal US shows a very thick, heterogeneous mass (arrows) arising from the surface of the osteochondroma (arrowheads)