2. In most cases, standard radiographs are sufficient for detecting skeletal tumors.
When evaluated together with clinical data (e.g., patientâs age and sex, anatomic
location of the lesion, clinical presentation), radiographs are the best predictors of the
histologic condition of the lesion.
ï¶Whereas plain radiographs may be sufficient for diagnosis, MRI and CT are
fundamental in staging skeletal tumors.
ï¶To fully characterize a tumor in an anatomically complex area such as the spine,
scapula, or pelvis or in a periarticular location, however, magnetic resonance imaging
(MRI) or computed tomography (CT) is often necessary
3. PET/CT has partially replaced bone scintigraphy as the modality of choice to screen for
skeletal metastases(has higher sensitivity, specificity, positive predictive value, negative
predictive value)
ï¶Although MRI is more sensitive than scintigraphy in detecting metastases , MRI is not an
efficient technique for evaluating the entire skeleton.
ï¶In the past, amputation was the treatment of choice in bone tumors without metastasis.
ï¶With improved surgical technique and aggressive chemotherapy, however, limb-
sparing operations can be performed, providing better functional results without
affecting survival.
ï¶In planning resection, accurate preoperative staging is essential. The initial CT or MRI
procedures should be performed before biopsy; afterward it is often difficult to
distinguish tumor from edema, hemorrhage, and granulation tissue.
4. MRI is superior for determining muscle compartment and vascular
involvement because of the intrinsic contrast among tumor mass, muscle, and
fat, without the need for enhancement with contrast medium.
ï¶CT is superior for detecting subtle cortical invasion and periosteal and
endosteal reaction and for depicting matrix calcification or ossification
ï¶Both MRI and CT are useful in evaluating the response to chemotherapy
and radiation therapy.
ï¶Signs of response to treatment are decreased tumor size, improved
delineation of the mass, reappearance of fat planes between muscle groups,
and calcification or ossification of the tumor
5. Intravenous administration in CT >> vascularity of tumor and distinguishing necrosis from viable T
CT angiography is useful in the assessment of the neurovascular bundle and in surgical planning
ï¶Numerous pulse sequences are available for the evaluation of musculoskeletal tumors, including spin
echo and fast-spin echo, inversion recovery, gradient echo, chemical shift, and diffusion-weighted
sequences
ï¶T1-weighted sequence in the sagittal or coronal plane, followed by either a double-echo (proton-
density, T2-weighted) fast-spin echo sequence or a T2-weighted, fat-saturated, fast-spin echo sequence
in the axial plane.
ï¶A short tau inversion recovery (STIR) sequence is occasionally obtained to increase the conspicuity of a
lesion.
ï¶Body coils are used when an entire bone or soft tissue region is being evaluated for the detection of
skip lesions or for surgical planning
ï¶Contrast enhancement is useful in grading a lesion, assessing response to treatment, and distinguishing
postoperative changes from recurrence
7. Enchondroma is a common benign primary osseous tumor
only nonossifying fibromas and exostosis are more common
ï¶There is no sex predilection
ï¶approximately 50% of these tumors occur in the hands, multiple in ollier and mafucci
syndrome
ï¶asymptomatic unless they are undergoing malignant transformation or the bone is fractured
ï¶Enchondromas are typically round or oval lesions with well-defined lobulated borders
ï¶The unmineralized matrix exhibits soft tissue attenuation on CT and homogeneous high signal
intensity on T2-weighted MRI.
ï¶ Calcification with a ring-and-arc appearance, which suggests a chondroid matrix, is best
identified on plain radiography and CT.
ï¶Calcifications are not consistently identified with MRI; when seen, however, they have low
signal intensity on all sequences
8. Benign and malignant chondroid lesions can have a similar appearance, making it
difficult or impossible to differentiate an enchondroma from a low-grade
chondrosarcoma.
ï¶ The presence of a soft tissue mass or cortical erosion or pain in the absence of
fracture, however, increases the likelihood of malignancy
enchondroma Bone infarct
9. size
ï lesion size over 5-6 cm favors chondrosarcomas
cortical breach
ï seen in 88% of long bone chondrosarcomas
ï seen in only 8% of enchondromas
deep endosteal scalloping involving > 2/3 of
cortical thickness
ï seen in 90% of chondrosarcomas
ï seen in only 10% of enchondromas
permeative or moth-eaten bone appearance
ï seen in high-grade chondrosarcomas, not in low-grade
tumors
soft tissue mass beyond bone
ï not seen in enchondroma
increased uptake on bone scan
seen in 82% of chondrosarcomas
seen in only 21% of enchondromas
location
hands and feet are uncommon locations
for chondrosarcoma
outside hand and feet, chondrosarcomas outnumber
enchondromas 5:1
spine, pelvis, sacrum, and ribs are rare locations
for enchondromas
patient age
enchondromas commonly appear in young adults
chondrosarcomas tend to appear in middle-aged patients
pain
chondrosarcomas almost always present with pain
enchondromas are painless unless they cause
a pathological fracture
*Calcification resorption
10. CHONDROSARCOMA
Chondrosarcoma is a malignant chondroid tumor
It is the third most common primary malignant bone tumor after plasmacytoma and osteosarcoma.
Its peak incidence is between 30 and 60 years of age.
Locations: long bones(femur,humerus,tibia),pelvic, rib, spine, sternum, scapula, skull base
Based on their intraosseous location, chondrosarcomas can be divided into central and peripheral
lesions.
Most chondrosarcomas (â75%) are primary and arise de novo, but the remaining 25% are
secondary and develop from malignant transformation of a benign lesion such as enchondroma,
osteochondroma, or rarely chondroblastoma.
Central chondrosarcomas occur in both tubular bones (e.g., femur, proximal humerus, proximal
tibia) and flat bones (e.g., pelvis).
Peripheral chondrosarcomas most commonly arise in flat bones (e.g., pelvis, ribs) and the spine.
11. On MRI, chondrosarcoma has a characteristic multilobular configuration.
The lobules of hyaline cartilage have intermediate signal intensity, similar to that of
muscle, on T1-weighted images ; they have homogeneous high signal intensity on T2-
weighted images.
The fibrous septa have low signal intensity on both T1- and T2-weighted images, but
they enhance after gadolinium administration.
Calcifications are common in low-grade chondrosarcoma and are best seen by
conventional radiography and CT.
Endosteal scalloping is also best depicted with CT and plain radiography.
12. Chondroblastoma
ï¶ Chondroblastoma is a rare benign tumor of cartilaginous origin composed of chondroblasts.
ï¶ Its peak incidence is in individuals between 10 and 20 years of age.
ï¶ It is more common in males, with a male-to-female ratio of 2 : 1.
ï¶humerus (most frequent), femur and tibia. Approximately 10% are found in the hands and feet
ï¶Chondroblastoma involves the epiphysis, apophysis, or both (apophysis: greater trochanter of the femur, greater
tuberosity of the humerus, acromion, calcaneus, or talus and patella)
ï¶Chondroblastomas are seen as well defined lucent lesions, with either smooth or lobulated margins and a thin
sclerotic rim, arising eccentrically in the epiphysis of long tubular bones
ï¶Internal calcifications can be seen in 40-60% of cases and joint effusion is seen in one-third of patients.
ï¶the tumor may extend into the metaphysis after destroying the growth plate. CT accurately demonstrates the
extent of the lesion as well as matrix calcifications and subtle cortical infractions.
ï¶Extension through the growth plate is best detected with conventional tomography or MRI because the growth
plate is usually best visualized in the sagittal or coronal plane
ï¶Both T1- and T2-weighted MRIs demonstrate a peripheral rim of signal void that corresponds to the sclerotic
margin of the lesion.
ï¶Abnormal signal intensity large areas of bone marrow surrounding the lesion has been seen and probably
represents bone marrow edema.
ï¶Fluid levels may be present in cystic components, corresponding to aneurysmal bone cysts
13. Common differential diagnoses for epiphyseal lesions include the following :
chondroblastoma: rare eccentric epiphyseal , in young adults(<20 year) ; sclerotic margin, 50% calcification
,it usually does not extend into the metaphysis, and usually does not extend beyond the bone, the presence
of solid or layered periosteal reaction distant to the lesion (involving the diaphysis) is distinctive for
chondroblastoma, +- FF level, +- pathologic fx, most common humerus, adjacent BM edema
giant cell tumor : eccentric epiphyseal, young adult(20-50);non sclerotic margin , no matrix calcification, it can
extend to involve the adjacent metaphys, can have solid component +- FF level, +- pathologic fx , most
common around the knee, no adjacent BM edema
geode/intraosseous ganglion: well defined lytic with sclerotic rim
aneurysmal bone cyst (ABC): usually metaphyseal, but if it occurs after the growth plate is obliterated, it may
extend into the epiphysis
AVN: sub-chondral lucency or sclerosis, double line sign, crescent sign
osteomyelitis or Brodie abscess: lytic lesion often in an oval configuration that is oriented along the long axis
of the bone, surrounded by a thick dense rim of reactive sclerosis or PR, adjacent BM edema , penumbra sign,
cloaca sign
clear cell chondrosarcoma: clear cell chondrosarcoma include: older age (20-50), larger mass, absent
adjacent bone edema, high T2 signal (solid component of chondroblastomas tend to be of an intermediate
signal on all sequences)
rarely: osteosarcoma and osteoblastoma, brown tumor, haemophilic pseudotumor, enchondroma, osteoid
osteoma, metastasis
15. GIANT CELL TUMOR
âąAlthough giant cell tumor is found relatively frequently, malignant transformation is rare, occurring in fewer than 10% of
lesions.
âąThere is a slight female preponderance, and the peak incidence is between 20 and 49 years of age.
âąIt is rare before closure of the growth plate or after age 50. This tumor is localized to the metaphysis before closure of the
growth plate.
âąNinety percent of cases involve the long bones, where the lesion is localized to the metaepiphyseal region.
âąMore than 50% of giant cell tumors involve the knee (metaepiphyseal region of the distal femur and proximal tibia).
âąOther bones that can be affected include (in order of frequency) the distal radius, sacrum, distal tibia, proximal humerus,
pelvis, and proximal femur.
âąOn CT, giant cell tumors appear as lytic lesions with thinning and erosion of the cortex .
âąA sclerotic margin may be present between the tumor and the normal marrow cavity.
âąOn MRI, giant cell tumors are well defined, with a low-signal-intensity rim or halo surrounding the tumor.
âąOn T1-weighted images they have intermediate signal intensity and are usually homogeneous; on T2-weighted images they
have intermediate to high signal intensity and may be inhomogeneous.
âąLocal areas with increased signal intensity may be seen on both T1- and T2-weighted images and represent hemorrhage.
âą Fluid-fluid levels, often seen in aneurysmal bone cysts and telangiectatic osteosarcomas, are present only rarely in giant cell
tumors.
âąBoth CT and MRI accurately demonstrate the intraosseous and soft tissue extension of the tumor
âąCT is better at showing cortical destruction, whereas MRI is better at demonstrating intraarticular involvement
16.
17. RCC
GCT MM chordoma
Brown tumor
Brown tumor
Brown tumor
MFH
Telangiectatic
OS
Giant cellârich
OS
Clear cell
chondrosarcoma
Fibroblastic
OS
T2
Midline
cal
Multiple,osteoporosis,other findings
Ddx:ABC,chondroblastoma,IOL
18. SIMPLE BONE CYST
The simple bone cyst is a benign lesion of unknown cause. It arises in the metaphysis of the bone, but with
growth it tends to move away from the growth plate toward the diaphysis.
It is a common bone lesion, following only nonossifying fibromas and exostoses in prevalence.
The male-to-female ratio is 2.5 : 1. It can be seen in any age group but is very rare before age 5 and
after age 20.
The most common site is the proximal humerus, followed by the proximal femur. All other locations are
rare
Simple cysts are central, lytic, expansile lesions. Their radiographic appearance is usually diagnostic, and
in most cases neither MRI nor CT is necessary. They are well defined and because of their fluid content
have low signal intensity on T1-weighted images and high signal intensity on T2
Typically they are homogeneous on both T1- and T2-weighted images unless hemorrhage has occurred.
Peripheral low-signal-intensity borders represent reactive sclerosis.
No edema is present in the surrounding bone marrow or muscle.
CT is superior to MRI in detecting subtle infractions of the lesion.
Fallen fragment sign
19. ANEURYSMAL BONE
CYST
Aneurysmal bone cysts are expansile lytic lesions that contain thin-walled cystic cavities; 75% are seen in patients
younger than 20 years; they are rare after age 30. There is a slight female predominance, with a male-to-female
ratio of 1 : 1.5.
Aneurysmal bone cysts can occur in any bone but arise predominantly in the long bones and spine. In the long bones
they are usually metaphyseal or metadiaphyseal.
In the spine they involve the posterior elements and may extend into the body. (only body involvement rare)
On CT the cyst appears as an expansile lesion with a thin cortical shell .
Fluid-fluid levels this is best visualized if the patient is immobilized for some time before scanning.
Fluid-fluid levels are a nonspecific finding and have also been described in giant cell tumors, chondroblastoma, and
telangiectatic osteosarcoma(zone of transition, PR, soft tissue mass, cortical erosion or destruction)
On both T1- and T2-weighted MRI, an aneurysmal bone cyst appears as a well-defined expansile mass with multiple
internal septations surrounded by a well-defined, low-signal-intensity rim of variable thickness and variable edema
One cavity may have signal intensity characteristics that are markedly different from those of an adjacent cavitys.
Septations within the lesion enhance after administration of gadolinium, but the cystic component does not enhance.
20. NOF
Nonossifying fibroma and fibrous cortical defects share the same tissue appearance and differ only in
size(2 cm), with fibrous cortical defects being smaller.
They are sometimes called fibroxanthomas because they contain spindle-shaped fibroblasts and xanthoma
(foam) cells.
They are the most common benign lesion of bone and have been reported in 30% of normal children.
Most of these nonneoplastic developmental aberrations are asymptomatic and disappear spontaneously.
The male-to-female ratio is 1.5 : 1, and the peak incidence occurs around age 10.
Nonossifying fibromas and fibrous cortical defects are usually localized to the metaphysis of a long bone
and are most commonly found about the knee (distal femur and proximal tibia). uncommon in the upper
extremities
Their radiographic appearance is often pathognomonic(may be incidental), no additional studies needed.
Non-ossifying fibromas are typically multiloculated lucent lesions with a sclerotic rim.
In the early stages when the lesion is completely lytic on plain radiographs, it may have high signal intensity on T1-
weighted images as a result of an abundance of xanthoma cells containing fat.
Linear structures of low signal intensity are often present and represent fibrous septa or osseous pseudosepta.
When the lesion starts healing, it has low signal intensity on both T1- and T2-weighted images because of increased
fibrous collagen, mineralization, and possibly hemosiderin deposits.
The lesions are always well defined and are never surrounded by bone marrow edema or PR or soft tissue mass
Multiple NOF: NF I
Multiple FD:MAS
FD+ myxoma: mazabraud
Mutiple GCT: paget
Multiple enchondroma:ollier
and mafucci
adamantimoma
OFD
21. CMF
Chondromyxoid fibroma is composed of three principal elements: chondroid,
fibrous, and myxoid tissue.
It is the least common of the benign cartilaginous bone neoplasms.
There is a male predominance, with a male-to-female ratio of 1.5 : 1 to 2 : 1.
usually under 30 YO
The tumor tends to occur around the knee joint(upper one-third of the tibia) but can involve any bone.
Most chondromyxoid fibromas are located in the metaphyseal region of long bones (60%), and may extend to the
epiphyseal line
lobulated or oval eccentric lytic lesion, well defined sclerotic margin: ~85%, often expansile, with long axis parallel
to long axis of long bone, no PR (unless fx), pseudotrabeculation(60%),matrix ca uncommon(2-15%)
The tumor is usually solid but may contain cystic or hemorrhagic areas and rarely may be associated with an
aneurysmal bone cyst.
On MRI the signal intensities of this tumor vary with the proportions of chondroid, fibrous, and myxoid tissues present.
(T1low to iso ,T2 iso to high,+- low signal foci peripheral and central in T2, Minimal surrounding bone marrow
edema,T1 +c: peripheral nodular or diffuse enh)
CT may be better than MRI in delineating matrix calcification and sclerosis around the tumor
Clinically, patients with CMF can present with progressive pain
Ddx: chondroblastoma, GCT, ABC, enchondroma, NOF
22.
23. OSTEOCHONDROMAS
Osteochondromas (exostoses) are the second most common benign tumor of bone after nonossifying
fibromas.
The male-to-female ratio is 1.5 : 1 to 2 : 1.1
Although these are congenital lesions, they are usually discovered in individuals between 10 and 20
years of age.
Multiple exostoses are uncommon, occurring only one tenth as frequently as solitary exostosis, but they
manifest earlier, usually before 10 years of age(diaphysial aclasia)
Ninety percent of osteochondromas originate from a long bone close to the metaphysis.
The most common locations are around the knee (distal femur and proximal tibia) and the proximal
humerus.
The morphology of an osteochondroma is more important than the signal intensity in terms of diagnosis.
The incidence of malignant transformation is approximately 1% for solitary osteochondromas and 5%
to 25% for hereditary multiple exostoses.
Both CT and MRI demonstrate the continuity of the cortex and medullary cavity of the
osteochondroma with that of the parent bone
The perichondrium is well seen on T2-weighted MRI as an area of low signal intensity surrounding the
outer surface of the high-signal-intensity cartilage cap.
MRI measurements of cartilage cap thickness are also accurate
F>T>H
24. whereas CT measurements of maximal cartilage thickness are often imprecise.
The thickness of this structure is important in distinguishing benign osteochondroma
from exostotic chondrosarcoma. According to most authors, the cartilage cap is usually
thicker than 1.5 cm in chondrosarcoma.
Complications of osteochondroma include nerve injury, vascular injury, deep venous
thrombosis, and bursa formation.
Formation of a bursa over an osteochondroma is common, and the bursa is usually
asymptomatic; if it becomes inflamed and distended, it can be painful.
On T2-weighted images, bursal fluid has high signal intensity similar to that of the
cartilage cap, and it can be difficult to differentiate the two
On gradient echo sequences, cartilage has a lower signal intensity than that of fluid,
and the diagnosis is easily made.
A rarer complication is formation of a pseudoaneurysm adjacent to the exostosis
25. âągrowth after skeletal maturity
âąlucency (new)
âąadditional scintigraphic activity
âądestruction (cortical)
âąpain after puberty
âąand
âąsoft tissue mass
âąthickened cartilage cap
âągreater than 1.5 cm
sessile exostosis vs
Erlenmeyer flask deformity
sessile exostosis
vs
Cortical desmoid
and paraosteal
osteosarcoma
Achandroplasia trumpet bone
26. OSTEOID OSTEOMAS
Osteoid osteomas are relatively common; only osteochondromas and fibrous cortical defects are more prevalent.
The male-to-female ratio is 3 : 1. They typically occur in teenagers and young adults and are
rare before age 5 and after age 30.
These tumors occur most frequently in the femur, tibia, and humerus and involve the diaphysis and less commonly
the metaphysis.
When the spine is involved, the posterior elements are typically affected. The main clinical symptom is pain
relieved by aspirin.
CT is very accurate in detecting the nidus and is preferable to MRI for evaluating osteoid osteoma.
Occasionally an osteoid osteoma can be confused with a stress fracture on MRI because of edema in the bone
marrow. On CT the typical appearance of an osteoid osteoma is an area of sclerosis surrounding a small (<1 cm)
radiolucent nidus .
Lesions larger than 1.5 cm are considered osteoblastomas.
The nidus may contain a variable number of calcifications ranging from none to enough to cause almost complete
calcification, with only a thin peripheral rim of low density.
27. thin-section CT with less than 2-mm slices is needed because the nidus is often less than 1 cm in
diameter.
The nidus enhances on dynamic CT scans; this enhancement helps in differentiating osteoid
osteoma from Brodieâs abscess.
Depending on the degree of calcification, the nidus has low signal intensity on T1-weighted
images and variable intensity on T2-weighted images.
The surrounding bone marrow has low signal intensity on all pulse sequences in the presence of
reactive sclerosis or high signal intensity on T2-weighted images in the presence of edema .
Osteoid osteomas in younger patients tend to be associated with more extensive peritumoral
edema. When the osteoid osteoma is intraarticular, an associated joint effusion may be detected.
CT is used to direct percutaneous ablation of osteoid osteomas
Uncommon locations: spine,hand,feet,skull,scapula,rib,pelvis,mandible,patella
28. DDX AND PITFALLS
*Prominent periosteal reaction and a young age increase the possibility of
osteomyelitis or a malignant bone tumor, such as Ewing sarcoma.
*The presence of severe synovial hypertrophy and a large joint effusion may cause
an osteoid osteoma to resemble septic arthritis or chronic inflammatory arthritis
*When a small nidus is masked by extensive bone marrow and soft-tissue edema,
traumatic injury or infection may be suspected
*vascular groove sign vs cloaca (sinus tract in Brodie abscess)
*A stress fracture appears as an infraction in the center of an area of cortical
thickening, whereas osteoid osteoma appears as a round nidus
*osteoid osteoma has smooth inner margins whereas a Brodie abscess has irregular
margins and a sequestrum, if present, is irregular and eccentric
Vascular groove sign or feeding vessel sign
29. hypoattenuating intracortical lesion with
wire-netting appearance
Chondroblastoma Like OO have BM edema and PR but
no reactional sclerosis, lobulated,epiphyseal, punctate cal
Glomus doesent have nail bed hypertrophy
And homogenously high in T2 without cal
SIF or SONK OO
OO
Brodie abscess
30. OSTEOBLASTOMA
Osteoblastoma is a rare benign tumor.
It is at least four times less common than osteoid osteoma. There is a male predominance, with a
male-to-female ratio of 2.5 : 1.
Its peak incidence is in the second decade, and it is rare before age 10 and after age 30.
Its most common location is the spine, usually in the posterior elements. In the long bones it is most often
located in the metadiaphyseal region; in rare circumstances it can extend into the epiphyses in adults.
Osteoblastomas may be associated with aneurysmal bone cyst
On CT, osteoblastoma appears as an expansile lytic lesion, often with a mineralized matrix
surrounded by a thin bony shell. Dense sclerosis and periosteal reaction may occasionally be present.
Osteoblastoma typically has low to intermediate signal intensity on T1-weighted images and high
signal intensity on T2-weighted images.
Edema in the surrounding soft tissues and in the bone marrow beyond the tumor margins (within
adjacent vertebrae, surrounding paraspinal soft tissues, and ribs within proximity)
31. DDX
OB VS OO: have a smaller response to salicylates; grow progressively; have the
potential to be malignant; may be associated with other tumors; lead to fewer
inflammatory changes; and less often lead to reactive sclerosis, is larger than 2 cm,
an associated soft tissue mass may also be present, more expansile ,sometimes with
cortical destruction
No matrix ca, no BM
edema
Cortical RCC
32. INTRAOSSEOUS LIPOMA
Intraosseous lipoma is a rare benign tumor, accounting for less than 0.1% of primary bone
tumors.
There is a male predominance, with a male-to-female ratio of 1.6 : 1. Its peak incidence is in
the fifth decade, but there is a wide age range from the second to eighth decades.
Its most common location is in the metaphyses of long bones, especially the femur, tibia, and
fibula, and in the calcaneus.
The radiographic appearance of lipoma of bone is often pathognomonic; it is a well-defined
lesion with sclerotic borders and central mineralization, and in most cases, no additional studies
are necessary.
CT and MRI are usually diagnostic because they demonstrate the fat content of the lesion.
With involution of the intraosseous lipoma, fibrous proliferation and cystic degeneration can
be seen and may become a predominant feature on CT and MRI
Liposlerosing
myxofibrous
tumor(no macro fat)
FD
33. MULTIPLE MYELOMA
Multiple myeloma is a multifocal malignant proliferation of plasma cells and is the most
common primary malignant tumor of the skeleton.
There is a male predominance, with a male-to-female ratio of 1.5 : 1. It is common after age
50 and rare before age 30.
Locations(red marrow): skull, ribs, sternum, pelvis, proximal humeral metaphysis, and proximal
femoral metaphysis.
Infiltration of bone marrow has two forms: diffuse and focal
Diffuse form is difficult to image; the only MRI manifestation is an inhomogeneous bone
marrow signal intensity that is subjective and difficult to quantitate. CT, plain radiographs, and
scintigraphy may result in negative findings.
In the focal form, normal bone marrow is displaced by nodules composed entirely of myeloma
cells.
Patterns:
1. Multiple punched
out
2. Diffuse osteopenia
3. Salitory
plasmacytoma
4. sclerotic
34. Untreated myelomatous lesions have decreased signal intensity on T1-weighted
images and increased signal intensity on T2-weighted images when compared to the
surrounding bone marrow.
CT demonstrates purely osteolytic lesions in the trabecular bone, which occasionally
extend to involve the cortex.
Multidetector CT is able to demonstrate smaller lesions than MRI can.
After irradiation, these lesions show low signal intensity on both T1- and T2-weighted
images, and a sclerotic border develops, as seen on CT.
Whole-body MRI is used for staging and monitoring response to treatment
Ddx mouth eaten:
Adult: MM- met-PBL
Pediatric:
OS
neuroblastoma
Leukemia
Ewing sarcoma
OM
EG
No acral lesion
Malignant acral lesions:
Met: lung SCC,breast,RCC,prostate
Sarcoma(chondro-ewing-synovial-fibro)
35. OSTEOSARCOMA
Osteosarcoma is a malignant neoplasm characterized by production of osteoid by tumor cells.
It is the second most common primary malignant tumor of bone after plasmacytoma.
It is a rare tumor, representing only 0.2% of all malignant tumors. There is a male
predominance, with a male-to-female ratio of 2 : 1. Its peak incidence is in the second decade;
it is rare before age 10 and after age 30.
Osteosarcoma can occur in any bone, but it has a strong predilection for the distal femur,
proximal tibia, and proximal humerus. Two thirds of osteosarcomas are localized to the knee or
shoulder.
Osteosarcomas can be divided into two categories: primary osteosarcomas, which arise de
novo, and secondary osteosarcomas, which develop in abnormal bones.
Underlying bone abnormalities include Pagetâs disease, complications of radiation therapy,
multiple enchondromas, multiple osteochondromas, chronic osteomyelitis, fibrous dysplasia, or
infarct. Secondary osteosarcomas usually affect older people.
36. MRI is useful for staging the tumor and for follow-up after treatment. The osteoblastic
component of the tumor has low signal intensity on all sequences.
The nonmineralized component has low signal intensity on T1-weighted images and
high signal intensity on T2-weighted images.
Bone marrow extension is best seen on T1, on which loss of the high signal intensity of
normal bone marrow can be appreciated. Soft tissue extension is best seen on T2,
whereas tumor and muscle may have the same signal intensity on T1.
CT is better than MRI in demonstrating matrix mineralization but is less accurate in
detecting skip lesions and bone marrow and soft tissue extension
Telangiectatic osteosarcomas contain large, cystic, blood-filled spaces with fluid-fluid
levels that may mimic an aneurysmal bone cyst; however, these tumors are usually less
well defined than aneurysmal bone cysts
Intramedullary: conventional (osteoblastic , chondroblastic,fibroblastic
,low grade central, telangiectatic, small cell
Surface: parosteal-periosteal-high grade surface
Extra skeletal
telangectatic
Low grade
central
OS
Small cell OS with
Pathologic fx
ESOS thigh
Desmoid
tumor
37. Local staging of bone tumors must include evaluation for skip metastases, which are defined as
synchronous smaller foci of tumor occurring in the same bone, anatomically separated from the
primary lesion, or as synchronous smaller foci of tumor on the opposite side of a joint.
MRI is the imaging modality of choice for detection of skip metastasis. In the last 2 decades
the development of aggressive chemotherapy has significantly improved survival of patients
with osteosarcoma, and imaging studies are used to evaluate the tumorâs response to
treatment.
CT findings of a positive response to treatment include (1) marked decrease in size or
complete disappearance of the soft tissue mass, (2) increased calcification of the mass, (3)
improved delineation of the margins, and (4) formation of a peripheral rim of calcification.
Decreased signal intensity of the nonmineralized mass on T2-weighted images is thought to
represent fibrosis or sclerosis of the tumor. Persistent high signal intensity may be a result of
nonresponding or necrotic tumor, reactive granulation tissue, or hemorrhage.
Administration of gadolinium cannot help distinguish viable tumor from reactive inflammation,
because both enhance; a lack of enhancement indicates tumor necrosis
38. EWINGâS SARCOMA
Ewingâs sarcoma is a malignant neoplasm that is probably of neuroectodermal origin.
Among primary malignant neoplasms of bone, it follows plasmacytoma, osteosarcoma, and
chondrosarcoma in frequency.
There is a male predominance, with a male-to-female ratio of 2 : 1.
Its peak incidence is in the second decade, with 90% of cases occurring between 5 and 25 years
of age.
Ewingâs sarcoma may involve any bone but has a predilection for the long bones and pelvis. In
the long bones it is localized to the diaphysis or metaphysis, and until the growth plate is open, it
does not extend to the epiphysis.
MRI facilitates staging of Ewingâs sarcoma and is better than CT for demonstrating bone marrow
and soft tissue involvement.
The MRI signal intensity characteristics of Ewingâs sarcoma are not specific and are similar to
those of other malignant neoplasms. The tumorâs signal intensity is lower than or equal to that of
muscle on T1-weighted images and is higher on T2-weighted images
39. MRI and CT are helpful in evaluating response to treatment. If the tumor is sensitive to
treatment, it decreases in size, the periosteal reaction matures, and the bone becomes
sclerotic.
High signal intensity on T2-weighted images after treatment does not always indicate
a poor response; it may represent necrosis, reactive granulation tissue, or hemorrhage.
Enhancement after gadolinium administration does not aid in distinguishing reactive
changes from residual tumor, but lack of enhancement indicates tumor necrosis
DDX:
<40: OS , Hemophilic Pseudo Tumor, GCT, FD
40<: Chondrosarcoma, NHL, met, plamacytoma, MFH
Ddx:OS
ES usually diaphysial but
OS metaphysical with ca
ALL
Ddx:neuroblastoma
40. Askin tumor
Ddx: rhabdomyosarcoma,neuroblastoma
fibrosarcoma
ES:
Ddx: rhabdomyosarcoma ,
met neuroblastoma
,lymphoma, OS,GCT,brown tumor
Extra skeletal ES
Ddx: high grade vascular tumros
like angiosarcoma or hemangiopericytoma
RMS,synovial sarcoma
ES metatars
Ddx: OS
Cloud like ca ES in
Hand,feet, flat bone
Other locations of ewing sarcoma
41. MRI is more accurate and sensitive than CT in evaluating soft tissue tumors
On MRI, benign lesions tend to have well-defined margins and homogeneous signal
intensity; they do not encase neurovascular bundles and are not surrounded by
peritumoral edema.
Conversely, malignant lesions typically have poorly defined margins, heterogeneous
signal intensity, neurovascular bundle encasement, and peritumoral edema.
Unfortunately a large overlap exists between benign and malignant lesions, and
MRIâs ability to differentiate benign from malignant soft tissue masses remains
controversial
Soft tissue tumors
43. LIPOMA
Lipoma is a benign tumor composed of mature adipose tissue. It is the most frequently
occurring benign soft tissue tumor and is often asymptomatic.
Superficial lipomas predominate in women, whereas deep lipomas are more common in
men. The peak incidence of lipomas occurs between 40 and 60 years of age.
Superficial lipomas are usually localized to the subcutaneous tissue of the trunk and
proximal extremities.
Deep lipomas are usually in the retroperitoneum, chest wall, and deep soft tissues of the
hands and feet.
On CT, lipomas have a low attenuation coefficient, equal to that of subcutaneous fat, and
they do not enhance after administration of contrast material. On MRI they have the same
signal intensity characteristics as subcutaneous fat on all imaging sequences .
On both CT and MRI, lipomas have a homogeneous appearance, although occasional thin
fibrous septa may be present.
44.
45. include vascular tumors (infantile hemangiomas, congenital hemangiomas) and vascular malformations.
Vascular malformations are divided into slow-flow vascular malformations (venous malformations, lymphatic
malformations, capillary malformations), fast-flow vascular malformations (arteriovenous malformations/fistulas), and
combined complex vascular malformations (capillary-venous, capillary-arteriovenous, lymphaticovenous
malformations)
On MRI, hemangiomas have a signal intensity similar to that of muscle on T1-weighted images and high signal
intensity on T2-weighted images. there may be variable amounts of fat and vessels within the mass
Phleboliths are seen as focal areas of low signal intensity on all imaging sequences, but they are better identified on
plain radiographs or CT. Serpiginous areas of low signal intensity are occasionally seen and represent flow voids in
larger feeding arteries or draining veins.
On MRI, arteriovenous malformations and arteriovenous fistulas have large tortuous vessels with flow voids due to
rapidly flowing blood. Feeding and draining vessels can be identified as vascular structures, but veins and arteries
cannot always be differentiated.
After administration of contrast, hemangiomas and arterial malformations and fistulas enhance avidly, venous
malformations have a variable enhancement, and lymphatic malformations do not enhance
Vascular
anomalies
46.
47. BENIGN NERVE SHEATH TUMORS
are divided into two groups: neurofibromas and schwannomas (neurilemomas). The
peak incidence of benign nerve sheath tumors is between 20 and 30 years of age,
with no sex predilection.
On CT and MRI, visualization of a nerve entering or exiting the mass is strongly
suggestive of a nerve sheath tumor.
Another characteristic of nerve sheath tumors is the presence on T2-weighted images
of the target sign, consisting of low to intermediate signal intensity centrally, with a
ring of high signal intensity peripherally.(60 % neurofibroma,15 % schwanomma)
Contrast enhancement on CT or MRI is variable and is commonly either heterogeneous
and diffuse or peripheral.
Lesions demonstrating the target sign on T2-weighted images usually enhance more
prominently centrally, with a reversal of the target sign
49. DESMOID TUMOR
Desmoid tumor is composed of fibroblasts. Histologically the tumor is benign and does not
metastasize, but it is locally aggressive, infiltrates contiguous structures, and tends to recur after
resection.
Desmoid tumors may occur at any age but are most often seen in the third and fourth decades.
On cross-sectional imaging desmoids have well-defined borders in two thirds of cases; in the rest,
the margins are infiltrative and poorly defined.
CT scans obtained without contrast enhancement show variable attenuation relative to muscle. After
intravenous contrast administration, desmoid tumors may or may not enhance.
Most are hyperdense or isodense with muscle on contrast-enhanced scans.
Desmoid tumors have a signal intensity lower than that of muscle on T1-weighted MRI and a
variable signal intensity on T2
They may have an aggressive appearance and be confused with malignant tumors.
The presence of areas of low signal intensity on both T1- and T2-weighted images, resulting from
fibrous tissue, is a clue to the correct diagnosis
50.
51. INTRAMUSCULAR MYXOMA
Intramuscular myxoma is a rare benign tumor that contains myxoid tissue. It occurs in people
between 40 and 70 years of age.
Usually it is solitary and has a slow growth rate. Multiple myxomas have been seen
in patients with fibrous dysplasia. The tumor is usually localized in a large muscle of the
thigh(quadriceps,adductors), hip (gluteus) or shoulder.
The CT appearance is a well-defined homogeneous mass with a density lower than that of
muscle. The mass typically does not enhance after administration of contrast material.
It has low to intermediate signal intensity on T1-weighted MRI and high signal intensity on T2
**MRI: a thin rim of fat at upper or lower pole, peri lesional edema
most lesions have peripheral enhancement, and 55% have heterogeneous internal enhancement
Ddx:PNST , hematoma, lymphangioma, myxoid sarcoma(lipo,fibro,chondro)
Mazabraud synd
Bright rim sign in US and T1
52. PVNS
Pigmented villonodular synovitis is a benign proliferative process of the synovial lining of a joint, bursa,
or tendon sheath. The cause of this lesion is unknown. Repeated trauma, repeated intraarticular
hemorrhage, and inflammation have been suggested as causes.
There are two forms. The focal form (also called giant cell tumor of the tendon sheath) is more common
and usually involves the tendon sheaths of the hands. The diffuse form involves large joints, especially the
knee. There is no sex predilection.
The peak incidence is between 20 and 40 years of age.
MRI characteristics are typical and often lead to the correct diagnosis. As a result of the deposition of
hemosiderin within the tumor, the lesion has areas of low signal intensity on both T1- and T2-weighted
images.
The presence of bone erosion on both sides of the joint also suggests the diagnosis. Joint effusion may be
present.
On CT, bone erosions have well-defined sclerotic borders.
On noncontrast scans, the soft tissue component may contain areas of high attenuation; these correspond
to deposits of hemosiderin
53. LIPOSARCOMA
Liposarcoma is a malignant soft tissue neoplasm that contains cells with lipoblastic or lipocytic
differentiation.
It is the most common malignant soft tissue tumor. Its peak incidence is between 50 and 60 years of
age; it is rare before age 20.
Liposarcomas are most common in the extremities, especially the thigh, and in the retroperitoneum.
Liposarcomas can be divided into four groups on the basis of their histologic characteristics: well
differentiated, dedifferentiated, myxoid, and pleomorphic.
The CT or MRI appearance depends on the degree of differentiation.67,74 Portions of the tumor
that contain fat demonstrate a low attenuation coefficient on CT scans and high signal intensity on
T1-weighted MRI.
Nonlipomatous portions of the tumor have a higher attenuation coefficient than fat on CT scans;
their signal intensity is similar to that of muscle on T1
More aggressive liposarcomas may contain no fat that is detectable by either CT or MRI. In these
cases the tumor is indistinguishable from other malignant soft tissue tumors
54.
55. UNDIFFERENTIATED PLEOMORPHIC SARCOMA
Undifferentiated pleomorphic sarcoma (UPS, previously known as malignant fibrous
histiocytoma [MFH]) is a heterogeneous group of disorders.
It is mainly composed of mesenchymal lineages that belong to established sarcoma subgroups
such as liposarcoma, fibrosarcoma, and leiomyosarcoma.
It was considered to be the most common malignant neoplasm of soft tissues, but with
advances in immunohistochemistry and gene expression analysis, most of these tumors have
been reclassified as myxofibrosarcoma, leiomyosarcoma, and liposarcoma.
It is seen more often in men, with a peak incidence between 50 and 70 years of age. Fifty
percent are localized in the lower extremities, 20% in the upper extremities, and 20% in the
abdominal cavity and retroperitoneum. Other locations are rare.
On MRI, undifferentiated pleomorphic sarcoma has low signal intensity with T1 weighting and
heterogeneous high signal intensity with T2 weighting .
On CT its density is the same as that of muscle, and it frequently contains areas of lower
attenuation that correspond to areas of necrosis. MRI is better than CT in determining the
extent of tumor, but CT is superior in detecting bone involvement and calcifications within the
tumor.
Calcifications are seen in up to 20% of undifferentiated pleomorphic sarcoma
56.
57. SYNOVIAL SARCOMA
Synovial sarcoma is a malignant soft tissue tumor that develops from undifferentiated mesenchymal
cells; despite its name, it does not arise from synovium. It is relatively common, following
liposarcoma and rhabdomyosarcoma in prevalence.
There is a slight male predilection and a peak incidence between 15 and 35 years of age.
Less than 10% of synovial cell sarcomas are within a joint. Usually they are adherent to a joint
capsule, bursa, fascia, or tendon sheath.
They are most common in the lower extremity around the knee
Synovial sarcoma has low to intermediate signal intensity on T1-weighted and heterogeneous high
signal intensity on T2-weighted MRI. This tumor is often multilocular with internal septation and
fluid-fluid levels are occasionally seen
Calcifications and bony invasion are present in 30% of cases and are best seen on CT.
"triple sign" which is due to areas of necrosis and cystic degeneration with very high signal,
relatively high signal soft tissue components and areas of low signal intensity due to dystrophic
calcifications and fibrotic bands
The presence of extensive calcification indicates a better prognosis
