In this presentation, systemic approach to bone tumor diagnosis by radiology procedures is explained. it is based on radiology assistant website

1. SYSTEMIC APPROACH TO
BONE TUMOR RADIOLOGY
Ramin Sadeghi, MD

2. INTRODUCTION
The most important determinators in the analysis of a potential bone
tumor are:
 The morphology of the bone lesion on a plain radiograph
 Well-defined osteolytic
 ill-defined osteolytic
 Sclerotic
 The age of the patient
The plain radiograph is the most useful examination for
differentiating these lesions.
CT and MRI are only helpful in selected cases.

4. The most reliable indicator in
determining whether these
lesions are benign or
malignant is the zone of
transition between the lesion
and the adjacent normal bone

5. Infections, a common tumor
mimic, are seen in any age
group.
Infection may be well-defined
or ill-defined osteolytic, and
even sclerotic.
EG and infections should be
mentioned in the differential
diagnosis of almost any bone
lesion in patients
Many sclerotic lesions in
patients > 20 years are healed,
previously osteolytic lesions
which have ossified, such as:
NOF, EG, SBC, ABC and
chondroblastoma.

6. ZONE OF TRANSITION
The zone of transition is the most reliable indicator in determining
whether an osteolytic lesion is benign or malignant.
The zone of transition only applies to osteolytic lesions since sclerotic
lesions usually have a narrow transition zone.

7. A small zone of transition results
in a sharp, well-defined border
and is a sign of slow growth.
In patients In patients > 30
years, and particularly over 40
years, despite benign
radiographic features,
metastasis or plasmacytoma also
have to be considered
NOF, SBC and ABC

8. Wide zone of transition
An ill-defined border with a
broad zone of transition is a
sign of aggressive growth
Infection and EG should always
be considered and DDx

9. Age is one of the most important
clues for correct diagnosis of
bone tumors

10. A periosteal reaction is a non-
specific reaction and will occur
whenever the periosteum is
irritated by a malignant tumor,
benign tumor, infection or
trauma.
There are two patterns of
periosteal reaction: a benign and
an aggressive type.
A Codman's triangle refers to an
elevation of the periosteum away
from the cortex, forming an
angle where the elevated
periosteum and bone come
together.

11. Benign periosteal reaction
Malignant lesions never cause a
benign periosteal reaction.
A benign type of periosteal
reaction is a thick, wavy and
uniform callus formation
resulting from chronic irritation.
Image: An OO

12. Aggressive periosteal reaction
This type of periostitis is
multilayered, lamellated or
demonstrates bone formation
perpendicular to the cortical
bone.
left:
Osteosarcoma with interrupted
periosteal reaction and
Codman's triangle proximally.
middle:
Ewing sarcoma with lamellated
and focally interrupted
periosteal reaction. (blue arrows)
right:
Infection with a multilayered
periosteal reaction.
Notice that the periostitis is
aggressive, but not as
aggressive as in the other two
cases.
Fibrous dysplasia, Enchondroma, NOF and SBC are common bone lesions.
They will not present with a periosteal reaction unless there is a fracture.
If no fracture is present, these bone tumors can be excluded.

13. CORTICAL DESTRUCTION
Cortical destruction is a common finding,
and not very useful in distinguishing between malignant and benign
lesions.
Complete destruction may be seen in high-grade malignant lesions,
but also in locally aggressive benign lesions like EG and
osteomyelitis.
More uniform cortical bone destruction can be found in benign and
low-grade malignant lesions.
Endosteal scalloping of the cortical bone can be seen in benign
lesions like FD and low-grade chondrosarcoma.

16. The images on the left show
irregular cortical destruction in
an osteosarcoma (left) and
cortical destruction with
aggressive periosteal reaction in
Ewing's sarcoma.

17. In ballooning the destruction of
endosteal cortical bone and the
addition of new bone on the
outside occur at the same rate,
resulting in expansion.
This 'neocortex' can be smooth
and uninterrupted, but may also
be focally interrupted in more
aggressive lesions like GCT.
left: Chondromyxoid fibroma
A benign, well-defined, expansile lesion
with regular destruction of cortical bone
and a peripheral layer of new bone.
right: Giant cell tumor
A locally aggressive lesion with cortical
destruction, expansion and a thin,
interrupted peripheral layer of new
bone.
Notice the wide zone of transition
towards the marrow cavity, which is a
sign of aggressive behavior.

18. In the group of malignant small
round cell tumors which include
Ewing's sarcoma, bone
lymphoma and small cell
osteosarcoma, the cortex may
appear almost normal
radiographically, while there is
permeative growth throughout
the Haversian channels.
These tumors may be
accompanied by a large soft
tissue mass while there is almost
no visible bone destruction.
The image on the left shows an
Ewing's sarcoma with permeative
growth through the Haversian
channels accompanied by a large
soft tissue mass.
The radiograph does not shown
any signs of cortical destruction.

19. Location within the skeleton
The location of a bone lesion
within the skeleton can be a clue
in the differential diagnosis.
The illustration on the left shows
the preferred locations of the
most common bone tumors.
In some locations, such as in the
humerus or around the knee,
almost all bone tumors may be
found.

20. LOCATION OF THE TUMORS IN THE
SKELETON
Hemangioma
spine, ribs, craniofacial bones, femur, tibia
•Lymphoma
femur, tibia, humerus, iliac bone, vertebra
•Metastases
vertebrae, ribs, pelvis, femur, humerus
•Non Ossifying Fibroma
tibia, femur, fibula, humerus
•Osteoid osteoma
femur, tibia, spine, tarsal bone, phalanx
•Osteoblastoma
spine, tarsal bone (calc), femur, tibia, humerus
•Osteochondroma
femur, humerus, tibia, fibula, pelvis
•Osteomyelitis
femur, tibia, humerus, fibula, radius
•Osteosarcoma
femur, tibia, humerus, fibula, iliac bone
•Solitary Bone Cyst
proximal humerus, proximal femur, calcaneal bone, iliac bone
•Aneurysmal Bone Cyst
tibia, femur, fibula, spine, humerus
•Adamantinoma
tibia shaft, mandible
•Chondroblastoma
femur, humerus, tibia, tarsal bone (calc), patella
•Chondromyxoid fibroma
tibia, femur, tarsal bone, phalanx foot, fibula
•Chondrosarcoma
femur, rib, iliac bone, humerus, tibia
•Chordoma
sacrococcygeal, spheno-occipital, cervical, lumbar, thoracic
•Eosinophilic Granuloma
femur, skull, iliac bone, rib, vertebra
•Enchondroma
phalanges of hands and feet, femur, humerus, metacarpals, rib
•Ewing's sarcoma
femur, iliac bone, fibula, rib, tibia
•Fibrous dysplasia
femur, tibia, rib, skull, humerus
•Giant Cell Tumor
femur, tibia, fibula, humerus, distal radius

21. Epiphysis
Only a few lesions are located in the
epiphysis, so this could be an important
finding.
In young patients it is likely to be either a
chondroblastoma or an infection.
In patients over 20, a giant cell tumor has
to be included in the differential diagnosis.
In older patients a geode, i.e. degenerative
subchondral bone cyst must be added to
the differential diagnosis.
Look carefully for any signs of arthrosis.
Metaphysis
NOF, SBC, CMF, Osteosarcoma,
Chondrosarcoma, Enchondroma and
infections.
Diaphysis
Ewing's sarcoma, SBC, ABC, Enchondroma,
Fibrous dysplasia and Osteoblastoma.

22. Centric in long bone
SBC, eosinophilic granuloma, fibrous dysplasia,
ABC and enchondroma are lesions that are located
centrally within long bones.
Eccentric in long bone
Osteosarcoma, NOF, chondroblastoma,
chondromyxoid fibroma, GCT and osteoblastoma
are located eccentrically in long bones.
Cortical
Osteoid osteoma is located within the cortex and
needs to be differentiated from osteomyelitis.
Juxtacortical
Osteochondroma. The cortex must extend into the
stalk of the lesion.
Parosteal osteosarcoma arises from the
periosteum.
SBC: central diaphyseal
NOF: eccentric metaphyseal
SBC: central diaphyseal
Osteoid osteoma: cortical
Degenerative subchondral cyst: epiphyseal
ABC: centric diaphyseal

23. MATRIX
Calcifications or mineralization within a bone lesion may be an
important clue in the differential diagnosis.
There are two kinds of mineralization:
 a chondroid matrix in cartilaginous tumors like enchondromas and
chondrosarcomsa and
 an osteoid matrix in osseus tumors like osteoid osteomas and osteosarcomas.

25. Chondroid matrix
Calcifications in chondroid
tumors have many descriptions:
rings-and-arcs, popcorn, focal
stippled or flocculent.
left: Enchondroma, the most
commonly encountered lesion
of the phalanges.
middle: middle: Peripheral
chondrosarcoma, arising from
an osteochondroma (exostosis).
right: Chondrosarcoma of the
rib.

26. Osteoid matrix
Mineralization in osteoid tumors can
be described as a trabecular
ossification pattern in benign bone-
forming lesions and as a cloud-like
or ill-defined amorphous pattern in
osteosarcomas.
Sclerosis can also be reactive, e.g. in
Ewing’s sarcoma or lymphoma.
left
Cloud-like bone formation in
osteosarcoma.
Notice the aggressive, interrupted
periosteal reaction (arrows).
right
Trabecular ossification pattern in
osteoid osteoma.
Notice osteolytic nidus (arrow).

27. POLYOSTOTIC LESIONS
Polyostotic lesions
NOF, fibrous dysplasia, multifocal osteomyelitis, enchondromas,
osteochondoma, leukemia and metastatic Ewing' s sarcoma.
Multiple enchondromas are seen in Morbus Ollier.
Multiple enchondromas and hemangiomas are seen in Maffucci's
syndrome.
Polyostotic lesions > 30 years
Common: Metastases, multiple myeloma, multiple enchondromas.
Less common: Fibrous dysplasia, Brown tumors of
hyperparathyroidism, bone infarcts.
Mnemonic for multiple oseolytic lesions: FEEMHI:
Fibrous dysplasia, enchondromas, EG, Mets and myeloma,
Hyperparathyroidism, Infection.

28. Polyostotic Fibrous Dysplasia.
Multiple osteolytic lesions in femur

29. SPINE LESIONS

30. 1-Hemangioma.
2-Metastasis.
3-Multiple myeloma.
4-Plasmocytoma: vertebra plana.
This 'Mini Brain' appearance of
plasmacytoma in the spine is
sufficiently pathognomonic to
obviate biopsy

32. ILL DEFINED OSTEOLYTIC TUMORS

34. Infection is seen in all ages.
Ill-defined borders in GCT is seen in a
locally aggressive lesion.
Chondrosarcoma is usually well-
defined, but high grade
chondrosarcoma can be ill-defined.
Metastases and myeloma are also
usually well-defined, but sometimes
ill-defined.

35. A partially ill-defined osteolytic lesion
with endosteal scalloping.
There are cloud-like calcifications
indicating a chondroid matrix.
These imaging findings and the size of
the lesion favor the diagnosis of a
chondrosarcoma.
Most commonly presents as a well-
defined lesion, but uncommonly it can
be encountered as an ill-defined lytic
lesion.
Calcifications can be seen when there is
a large myxoid component within the
tumor, but they are not essential for
the diagnosis.

36. Two other lesions that proved
to be a chondrosarcoma.
Notice that calcifications are not
essential in chondrosarcoma.

37. A lobulated partially ill-defined lytic
lesion of the proximal humerus.
The presence of calcifications
suggest that this is a chondroid
tumor.
The lytic parts with cortical
involvement and expansion should
raise the suspicion of a high grade
chondrosarcoma

38. EOSINOPHILIC GRANULOMA
EG is like osteomyelitis a great mimicker of benign and malignant
bone tumors.
Must be included in the differential diagnosis of almost any ill-
defined osteolytic bone lesion in patients under the age of 30.
May also present as a well-defined lesion.
EG can be excluded in patients > 30 years.
Commonly found in the skull, mandible, spine and long bones, but
can occur anywhere.

39. examples of EG with ill-defined
borders.
There are single or multiple layered
periosteal reactions.

40. a typical presentation of EG in the
skull as an ill-defined osteolytic
lesion

41. EWING’S SARCOMA
Most common presentation: ill-defined osteolytic lesion with multiple
small holes in the diaphysis of a long bone in a child with a large soft
tissue mass.
Presentation with pain, mass, fever, anemia and leukocytosis.
Most common location: femur, iliac bone, fibula, rib, tibia.
Differential diagnosis: Osteosarcoma, lymphoma, infection and EG.
Frequently aggressive type of periosteal reaction, but never a benign
type.

42. An ill-defined lytic lesion in the
femur of a young patient.
There is a permeative destruction
pattern with irregular cortical
destruction.
There is an aggressive periosteal
reaction (arrow).
This is also called sunburst
appearance

43. a patient with a Ewing's sarcoma in
the femur.
Notice the ill-defined osteolysis.
There is an aggressive periosteal
reaction

44. an ill-defined lytic lesion of the
right iliac bone in a young patient
which can easily be overlooked.
Final diagnosis: Ewing's sarcoma

45. GIANT CELL TUMOR
Giant cell tumor is a benign lesion, but can be locally aggressive.
A well-defined margin is associated with a locally less aggressive
biologic behavior.
In many cases the margin is ill-defined (figure).
These tumors often thin the cortex and may expand into the soft
tissues surrounding the bone.
Most commonly seen in age 20-40 years. In the age group > 40
years, metastasis and plasmacytoma have to be included in the
differential diagnosis.

46. On the left a giant cell tumor of the
distal radius with ill-defined
margins, destruction of the
subchondral bone plate and
extension towards the soft tissues.
On the right a giant cell tumor in
the proximal tibia with somewhat
better defined margin and non-
interrupted cortical bone.

47. LYMPHOMA
Primary non-Hodgkin's lymphoma of bone is rare.
Presentation: usually pain and palpable mass.
Preferential sites: femur and humerus.
Radiographic appearance may differ from virtually normal to severely
permeative.
Differential diagnosis:
 Ewing's sarcoma, however, lymphoma usually in higher age group
 Metastasis and plasmacytoma in age > 40y.

48. An ill-defined lytic lesion of the humerus
diaphysis.
Notice tunneling of the cortical bone (red
arrows).
On the MR notice the linear abnormalities
within the cortical bone and the
circumferential soft tissue mass.
Differential diagnosis (depending on age):
Ewing's sarcoma, osteomyelitis and bone
lymphoma.
Biopsy revealed Non-Hodgkin lymphoma

49. METASTASES
Most common malignancy in bone.
Must be considered in the differential diagnosis of any bone lesion in
a patient > 40 years.
May present as well-defined osteolytic, ill-defined osteolytic and also
as sclerotic bone lesion.
Majority of osteolytic metastases originate from breast, lung, kidney,
colon, melanoma and thyroid.

50. A 60 year old patient with a known
malignancy.
There is a lesion in the distal femur,
that you could easily overlook and
think that it was focal osteopenia.
The lesion presents as a large ill-
defined osteolytic mass extending
into the epiphysis and almost
abuttting the articular surface.
In a patient 20-40 years of age GCT
would be a possible diagnosis.
It proved to be a metastasis.

51. MULTIPLE MYELOMA
PLASMACYTOMA
Multiple myeloma must be included in the differential diagnosis of
any lytic bone lesion, either well-defined or ill-defined in age > 40.
Most common presentation: multiple lytic 'punched out' lesions. A
solitary presentation is referred to as plasmacytoma.
Usually no increased uptake on bone scan.
The most common location is in the axial skeleton (spine, skull,
pelvis and ribs) and in the diaphysis of long bones (femur and
humerus).

52. OSTEOMYELITIS
Broad spectrum of radiographic features.
May occur at any age, no typical location.
Radiographic appearance: predominant reactive changes, including
periosteal reaction, sclerosis and edema.
Periosteal reaction and permeative pattern may mimic malignant process:
Ewing's sarcoma, osteosarcoma, lymphoma, leukemia.
In the pediatric age group eosinophilic granuloma may also mimic
osteomyelitis.
Pediatric osteomyelitis: most commonly in central metaphysis, may cross to
epiphysis.
Adult osteomyelitis: most commonly in central metaphysis or diaphysis.
May be highly permeative with cortical breakthrough, abcesses and fluid
along fascia on MR imaging.

53. a subacute form of osteomyelitis.
There is an eccentric ill-defined
lesion seen on both sides of the
physeal plate in the proximal tibia.
This is highly suggestive for
osteomyelitis.
Other lesions do not cross the
growth plate in general.
On the right coronal T1-weighted
MR image reveals a well-defined
epi-metaphyseal lesion.
There is a dark peripheral zone of
reactive sclerosis, and extensive
edema with low signal Intensity in
the metaphysis.

54. an ill-defined osteolytic lesion in the
proximal metaphysis of the tibia
with extensive reactive sclerosis and
solid periosteal reaction.

55. OSTEOSARCOMA
Hallmark of osteosarcoma is the production of bony matrix, which is
reflected by the sclerosis seen on the radiograph.
Usually typical malignant features including permeative-motheaten
pattern of destruction, irregular cortical destruction and aggressive
(interrupted) periosteal reaction.
Occasionally an osteosarcoma may present as a lytic or mixed lytic-
sclerotic lesion.
Completely lytic osteosarcoma may represent telangiectatic subtype,
composed of multiple cavities filled with blood (may resemble
aneurysmal bone cyst!).

56. a mixed osteolytic and sclerotic
lesion in the proximal humerus with
irregular cortical destruction.
There is an aggressive periosteal
reaction and a soft tissue mass.

57. WELL-DEFINED OSTEOLYTIC TUMORS
AND TUMOR-LIKE LESIONS
These lesions are sometimes referred to as benign cystic lesions,
which is a misnomer since most of them are not cystic, except for
SBC and ABC.
It is true that in patients under 30 years a well-defined border means
that we are dealing with a benign lesion,
 but in patients over 40 years metastases and multiple myeloma have to be included
in the differential diagnosis.

59. In patients In patients > 40 years metastases
and multiple myeloma are by far the most
common well-defined osteolytic bone tumors.
Patients with Brown tumor in
hyperparathyroidism should have other signs of
HPT or be on dialysis.
Differentiation between a benign enchondroma
and a low grade chondrosarcoma can be
impossible based on imaging findings only.
Infection is seen in all ages.

60. MNEMONIC

61. FIBROUS DYSPLASIA
Fibrous dysplasia is a benign disorder characterized by tumor-like proliferation of fibro-
osseus tissue and can look like anything.
FD most commonly presents as a long lesion in a long bone.
FD is often purely lytic and takes on ground-glass look as the matrix calcifies.
In many cases there is bone expansion and bone deformity.
The ipsilateral proximal femur is invariably affected when the pelvis is involved.
When FD in the tibia is considered, adamantinoma should be in the differential diagnosis.
Discriminator:
 If periosteal reaction or pain is present, exclude fibrous dysplasia, unless there is a fracture.

62. Fibrous dysplasia: various
presentations with or without
sclerotic margin, with groundglass
appearance, with calcifications or
ossifications

63. ENCHONDROMA
In the phalanges of the hand it frequently presents with a fracture.
It is the most common lesion in the phalanges,
 A well-defined lytic lesion in the hand is almost always an enchondroma.
 In some locations it can be difficult to differentiate between enchondroma and bone infarct.
 It is almost impossible to differentiate between enchondroma and low grade chondrosarcoma based on radiographic features alone.
 Ollier's disease is multiple enchondromas. Maffucci's syndrome is multiple enchondromas with soft tissue hemangiomas.
Features that favor the diagnosis of a low-grade chondrosarcoma:
 Higher age
 Size > 5 cm
 Activity on bone scan
 Fast enhancement on dynamic contrast enhanced MR series
 Endosteal scalloping of the cortical bone
Discriminators :
 Must have calcification except in phalanges.
 No periostitis.

65. left
Fat suppressed coronal PD-image
of the knee. Typical
enchondromas in the femur and
tibia as seen frequently as
coincidental finding in MR-
examinations.
middle
Well-defined lytic lesion in the rib
with cortical thinning.
right
Well-defined lytic lesion with a
sclerotic margin and without
calcifications in the end phalanx.

66. EOSINOPHILIC GRANULOMA
EG is a non-neoplastic proliferation of histiocytes and is also known
as Langerhans cell histiocytosis.
It should be included in the differential diagnosis of any sclerotic or
osteolytic lesion, either well-defined or ill-defined, in patients under
the age of 30.
The diagnosis EG can be excluded in age > 30.
EG is usually monostotic, but can be polyostotic.

67. left
Osteolytic lesion arising from the
neurocranium with associated soft
tissue swelling.
middle
Mixed lytic-sclerotic lesion, not
well-defined with solid periosteal
reaction.
right
Sharply defined osteolytic lesion
of the skull. There is no 'button
sequestrum', which is more or less
pathognomonic.

68. Button sequestrum
Pathognomic of EG

69. GIANT CELL TUMOR
Giant cell tumor is a lesion with multinucleated giant cells.
In most cases it is a benign lesion.
Malignant GCT is rare and differentiation between benign or malignant GCT
is not possible based on the radiographs.
GCT is also included in the differential diagnosis of an ill-defined osteolytic
lesion, provided the age and the site of the lesion are compatible.
Discriminators:
 Epiphyses must be closed.
 Must be an epiphyseal lesion and abut the articular surface.
 Must be well-defined and non-sclerotic margin.
 Must be eccentric.

70. Giant cell tumor in the tibia abuts
the articular surface

71. NOF
A benign well-defined, solitary lesion due to proliferation of fibrous tissue.
 It is the most common bone lesion.
 NOF is frequently a coincidental finding with or without a fracture.
 NOF usually has a sclerotic border and can be expansile.
 They regress spontaneously with gradual fill in.
 NOF may occur as a multifocal lesion.
 The radiographic appearance is almost always typical, and as such additional imaging and biopsy is
not warranted.
Discriminators:
 Must be under age 30.
 No periostitis or pain.

73. OSTEOBLASTOMA
Osteoblastoma is a rare solitary, benign tumor that produces osteoid
and bone.
Consider osteoblastoma when ABC is in the differential diagnosis of a
spine lesion (figure).
A typical osteoblastoma is larger than 2 cm, otherwise it completely
resembles osteoid osteoma.
Discriminator:
Mention when ABC is mentioned.

75. METASTASES
Metastases are the most common malignant bone tumors.
Metastases must be included in the differential diagnosis of any bone lesion, whether
well-defined or ill-defined osteolytic or sclerotic in age > 40.
Bone metastases have a predilection for hematopoietic marrow sites: spine, pelvis, ribs,
cranium and proximal long bones: femur, humerus.
Metastases can be included in the differential diagnosis if a younger patient is known to
have a malignancy, like neuroblastoma, rhabdomyosarcoma, retinoblastoma.
Most common osteolytic metastases: kidney, lung, colon and melanoma.
Most common osteosclerotic metastases: prostate and breast.
Discriminator:
Must be over age 40.

77. MULTIPLE MYELOMA
Multiple myeloma must be included in the differential diagnosis of any lytic bone lesion,
whether well-defined or ill-defined in age > 40.
The most common location is in the axial skeleton (spine, skull, pelvis and ribs) and in the
diaphysis of long bones (femur and humerus).
Most common presentation: multiple lytic 'punched out' lesions.
Multiple myeloma doe not show any uptake on bone scan.
Discriminator:
Must be over age 40.
Differential diagnosis:
 multiple lesions: metastases.
 solitary lesion: chondrotumor, GCT and lymphoma.

79. On the left a CT-image of a
patient with multiple myeloma.
Notice the numerous osteolytic
lesions and permeative cortical
destruction pattern.
In the left sacral wing there is a
larger lesion with a high density
due to replacement of fatty bone
marrow by myeloma (red arrow).

80. ANEURYSMAL BONE CYST
ABC is a solitary expansile well-defined osteolytic bone lesion, that is filled with
blood.
It is named aneurysmal because it is expansile.
ABC is thought to be the result of a reactive process secondary to trauma or
increased venous pressure.
Sometimes an underlying lesion like GCT, osteoblastoma or chondroblastoma
can be found.
ABC can occur almost anywhere in the skeleton.
Discriminators:
 Must be under age 30.
 Must be expansile

81. ABC of the proximal fibula: well-
defined, expansile osteolytic
lesion with thin peripheral bone
shell

82. SOLITARY BONE CYST
Solitary bone cyst, also known as unicameral bone cyst, is a true cyst.
Many well-defined osteolytic lesions are often called cystic, but this is a misnomer.
SBC frequently presents with a fracture.
Sometimes a fallen fragment is appreciated.
Predilection sites: proximal humerus and femur.
Usually less expansion compared with ABC.
Differential diagnosis: ABC, FD when cystic.
SBC may migrate from metaphysis to diaphysis during growth of the bone.
Discriminators:
 Must be under age 30.
 Must be centric

83. SBC: well-defined osteolytic lesion
without expansion of the proximal
meta-diaphysis of the humerus
with pathologic fracture

84. HYPERPARATHYROIDISM
Brown tumors can occur in any bone and present as osteolytic lesions
with sharp margins.
Septa and ridges may be seen.
Differential diagnosis: ABC, metastases and GCT depending on
location and age.
Discriminators:
 Must have other signs of HPT.

85. a patient who had a nefrectomy
for renal cell carcinoma and who
was on dialysis.
Multiple well-defined osteolytic
lesions were found on a follow up
CT scan.
The differential diagnosis included
metastases and Brown tumors in
hyperparathyroidism.
Biopsy revealed Brown tumor.

86. INFECTION
Infection or osteomyelitis is the great mimicker of bone tumors.
It has a broad spectrum of radiographic features and occurs at any age and
has no typical location.
In the chronic stage it can mimic a benign bone tumor (Brodies abscess).
In the acute stage it can mimic a malignant bone tumor with ill-defined
margins, cortical destruction and an aggressive type of periostitis.
Only when there is a thick solid periosteal reaction we can recognize the
non-malignant underlying process.
Discriminators:
 None.

87. CHONDROBLASTOMA
The patella, carpal and tarsal bones can be regarded as epiphysis
concerning the differential diagnosis.
On the left a chondroblastoma located in the patella.
Discriminators :
 must be under age 30.
 must be in the epiphysis.

88. Chondroblastoma: notice
extensive edema (middle) and
fluid-fluid level due to secondary
ABC.

89. CHONDROMYXOID FIBROMA
Chondromyxoid Fibroma is a rare lesion.
CMF resembles NOF.
Preferential sites: proximal tibia and foot.
Although the name suggests that CMF is a chondroid lesion,
calcifications are usually not seen.
Discriminators :
 Mention when an NOF is mentioned.

90. CMF
There is an eccentric osteolytic
lesion in the metaphysis of the
proximal tibia.
On the inner side there is a sclerotic
margin.
On the outer side there is a regular
cortical destruction with peripheral
bone layer.
The MR also shows a sclerotic
margin with low signal intensity.

92. SCLEROTIC BONE TUMORS AND
TUMOR-LIKE LESIONS

96. BONE INFARCTION
Typical presentation: central lesion in metaphysis or diaphysis with a well
defined serpentiginous border.
May resemble cartilaginous tumors.
Causes: corticosteroid use, sickle cell disease, trauma, Gaucher's disease, renal
transplantation.
The term bone infarction is used for osteonecrosis within the diaphysis or
metaphysis.
If the osteonecrosis is located in the epiphysis, the term avascular osteonecrosis
is used.
Differentiating a bone infarct from an enchondroma or low-grade
chondrosarcoma on plain films can be difficult or even impossible.
Cartilaginous tumors in particular chondrosarcoma may show endosteal
scalloping, while a bone infarct does not.
Chrondroid tumors are more frequently encountered than bone infarcts.

98. On MR imaging bone infarcts are
characterized by irregulair
serpentiginous margins with low
signal intensity on both T1 and T2
WI and with intermediate to high fat
signal in the center part.
Enhancement after i.v. Gadolinium
is usually minimal or absent (see
right image).
At the periphery of the infarct a
zone of relative high signal
intensity on T2WI may be found.

99. BONE ISLAND
Benign lesion consisting of well-differentiated mature bone tissue
within the medullary cavity.
Also known as enostosis
The shape is usually round or oval.
Frequently encountered as a coincidental finding and can be found in
any bone.
Occasionally slowly enlargement can be seen.
Bone islands can be large at presentation.
Bone scan shows no high activity, opposed to low-grade intraosseous
osteosarcoma

101. CHONDROBLASTOMA
Typical presentation: well-defined osteolytic lesion in tarsal bone,
patella or epiphysis of a long bone in a 20-year old with pain and
swelling in a joint.
Abundant edema is almost always present.
DD: Ganglion cyst, osteomyelitis, GCT, ABC, enchondroma.

102. a lesion located in the epi- and
metaphysis of the proximal
humerus.
The lesion is predominantly
calcified.
Coronal T1W image shows
lobulated margins and peripheral
low SI due to the calcifications.

103. CHONDROSARCOMA
Most common malignant bone tumor, which is almost always low-
grade
Primary sites of origin: proximal long bones, around knee, pelvis and
shoulder girdle, usually central and metaphyseal
Radiological hallmark: formation of a chondroid (cartilagenous)
matrix, which presents as punctuated, stippled or popcorn-like
calcifications.
The chondroid matrix is of a variable amount from almost absent to
dens compact chondroid matrix.
Disappearane of calcifications in a pre-existing enchondroma should
raise the suspicion of malignant transformation.

105. a calcified lesion in the proximal
tibia without suspicious features.
This could very well be an
enchondroma.
There were other features that
favored the diagnosis of a low-
grade chondrosarcoma like a
positive bone scan and endosteal
scalloping of the cortical bone on
an MRI (not shown).
A chondrosarcoma was diagnosed
at biopsy.

106. a 44-year old male with a mixed
lytic and sclerotic mass arising from
the fifth metacarpal bone.
There are calcified strands within
the soft tissues.
T2-weighted axial MR image
demonstrates high signal intensity
of the tumor in the metacarpal
bone with extension of a lobulated
soft tissue mass.
Diagnosis: chondrosarcoma grade 2

107. a chondrosarcoma of the left iliac
bone.
Because of the large dimensions
with soft tissue extension on plain
radiograph and axial T2-weighted
MR image, a high grade
chondrosarcoma was suspected.
Biopsy showed grade 2
chondroarcoma.

108. two other lesions in different
patients that proved to be
chondrosarcoma.
The sclerotic lesion in the humeral
head could very well be a benign
enchondroma based on the imaging
findings.
Symptoms are usually absent,
however, in adult patients with a
chondroid lesion in a long bone,
particularly of larger size, always
consider low-grade
chondrosarcoma.

109. Plain radiograph and coronal T1-
weighted contrast-enhanced fat-
suppressed MR image of a mixed
lytic and sclerotic lesion of the
distal femoral diaphysis.
Notice the homogeneous thickening
of the cortical bone.
There are no calcifications.
The MR image shows that the lesion
has lobulated contours and nodular
enhancement.
The homogeneous enhancement in
the upper part with edema and
cortical thickening are not typical
for a low-grade chondrosarcoma.
A high grade chondrosarcoma must
be considered in the differential
diagnosis.
Biopsy revealed dedifferentiated
chondrosarcoma.

110. PERIPHERAL CHONDROSARCOMA
 Accounts for 8% of all chondrosaromas.
 Prevalence of 3-5% in patients with hereditary multiple osteohondromas.
 Development in centrally located osteochondromas like the pelvis, hip and shoulder is most
common.
Consider peripheral chondrosaroma in growing osteochondromas with or
without pain after closure of the physeal plate.
Radiographic or CT features that suggest malignancy:
 growth of osteohondroma in skeletally mature patients
 irregular or indistinct surface of lesions
 erosion or destruction of adjacent bone
 soft tissue mass with scattered or irregular calcifications
Use MRI with water-sensitive sequence (T2 FS) to determine cartilage cap
thickness.
Consider progression of osteohondroma to chondrosarcoma when cartilage cap
measures > 10 mm.

111. PERIOSTEAL OR JUXTACORTICAL
CHONDROSARCOMA
A juxtacortical chondrosarcoma has be considered in the differential
diagnosis when a mineralized lesion adjacent to the cortical bone is
seen.

112. Here a partially calcified mass
against the proximal humerus with
involvement of the cortical bone on
an axial CT image.
T2-weighted MR image reveals a
lobulated mass with high signal
intensity.
The bone marrow compartment is
not involved which is important for
the surgical strategy.
A periosteal chondroma may have
the same imaging characteristics,
however, these are almost always
much smaller.

113. Plain radiograph in another patient
shows irreglar mineralized lesion
with elevation of the periosteum
and cortical involvement. On the
right T2-WI with FS of same
patient.. The juxtacortical mass has
a high SI and lobulated contours.
DD: juxtacortical chondrosarcoma,
parosteal osteosarcoma.

114. ENCHONDROMA
Most commonly encountered bone tumor in the small bones of the
hand and foot.
Enchondroma is a fairly common benign cartilaginaous lesion which
may present as an entirely lytic lesion without any calcification, as a
dense calcified lesion or as a mixed lesion with osteolysis and
calcifications.
Enchondromas as well as low-grade chondrosarcomas are frequently
encountered as coincidental findings in patients who have a MRI or
bone scan for other reasons.

116. EOSINOPHILIC GRANULOMA
Typically presents as a lytic lesion in a flat bone, vertebra or diaphysis
of long bone.
May show extinction and become sclerotic and indolent,.
MR usually shows a large amount of reactive changes in bone and
soft tissue.
In the active phase there is multilaminar periosteal reaction and bone
and soft tissue edema.
Eosinophilic granuloma like osteomyelitis, can be a serious mimicker
of malignancy (particularly Ewing sarcoma).
Should be included in the differential diagnosis of young patient with
multiple lucent lesions (Langerhans cell histiocytosis).

118. a 20 year old patient with a
sclerotic expansile lesion in the
clavicle.
Notice that there are small areas of
ill-defined osteolysis.
In an older patient one should first
consider an osteoblastic metastasis.
If the patient had fever and a
proper clinical setting,
osteomyelitis would be in the
differential diagnosis.

119. FIBROUS DYSPLASIA
FD is often purely lytic, but may have a groundglass appearance as
the matrix calcifies.
Ossifications or calcifications can be present in variable amounts.

120. a rather wel-defined eccentric
lesion which is predominantly
sclerotic.
The differential diagnosis includes:
Fibro-osseous lesion like fibrous
dysplasia.
Non-ossifying fibroma which has
been filled in.
Adamantinoma in case of a
sclerotic lesion with several
lucencies of the tibia in a young
patient.

121. Here a well-defined mixed sclerotic-lytic
lesion of the left iliac bone.
The diagnosis was fibrous dysplasia.
DD: old SBC.
Bone scintigraphy can be either negative
or show limited uptake.
The signal intensity on MR depends on
the amount of calcifications and
ossifications and fibrous tissue (low SI)
and cystic components (high SI on T2).
Fibrous dysplasia can be monostotic or
polyostotic.
Usually it is a lesion of childhood or
young adults. Not infrequently
encountered as coincidental finding at
later age.
Central location most common with
some expansion and cortical thinning

122. Melorrheostosis is a dysplasia of
the bone, characterized by
apposition of mature bone on the
outer or inner surface of cortical
bone.
Usually one bone is involved.
The epiphysis, metaphysis and
diaphysis may be involved.
Usually new bone is added to one
side of the cortex only.
Complete envelopment may occur.
Here Melorrheostosis of the ulna
with the appearance of candle
wax.
A surface osteosarcoma could be
considered in the differential
diagnosis
Axial T1-weighted MR image
shows homogeneous low signal
intensity due to the compact bone
apposition.

123. METASTASES
Sclerotic osteoblastic metastases must be included in the differential
diagnosis of any sclerotic bone lesion in a patient > 40 years.
Most commonly originate from prostate and breast cancer and less
frequently from lung cancer, lymphoma or carcinoid.
In breast cancer, metastases may present as lytic lesions that may
become sclerotic expressing a favourable response to chemotherapy.

124. a patient with prostate cancer.
Notice the numerous
predominantly osteoblastic
metastases.

125. a patient with breast cancer.
There is a metastasis, which
presents as a subtle sclerotic
lesion in the humerus metaphysis.
This could be an osteoblastic
metastasis or an osteolytic
metastasis that responded to
chemotherapy.

126. a radiograph of the pelvis with a
barely visible osteoblastic
metastasis in the left iliac bone
(blue arrow).
Notice that CT depicts these
lesions far better (red arrows).

127. CT-images of a patient with
prostate cancer.
Notice the numerous ill-defined
osteoblastic metastases.

128. NON-OSSIFYING FIBROMA
Non-ossifying fibroma (NOF) can be encoutered occasionally as a
partial or completely sclerotic lesion.
Typically a NOF presents as an eccentric well-defined lytic lesion,
usually found as a coincidental finding.
These lesions usually regress spontaneously and may then become
sclerotic.
Other benign lesions, like solitary bone cyst, fibrous dysplasia,
chondroblastoma and other benign bone tumors may become inert
and may also become sclerotic.

129. on the left a typical osteolytic NOF
with a sharp sclerotic border.
The image on the right is of a
different patient who has an old
NOF that shows complete fill in.

130. an incidental finding of several
eccentric sclerotic lesions of the
distal femur.
These are inert filled-in non-
ossifying fibromas.
No further examination is needed.

131. OSTEOCHONDROMA
Osteochondroma is a bony protrusion covered by a cartilaginous cap.
Growth of the osteochondroma takes place in the cap, corresponding
with normal enchondral growth at the growth plates.
Accordingly, growth of osteochondromas is allowed until a patient
reaches adulthood and the physeal plates are closed.
Growth of osteochondromas at adult ages, which is characterized by
a thick cartilaginous cap (high SI on T2WI) should raise the suspicion
of progression to a peripheral chondrosarcoma.

132. a patient with a broad-based
osteochondroma.
Notice that the cortical bone
extends into the lesion.
This feature differentiates it from a
juxtacortical tumor.

133. a patient with a broad-based
osteochondroma with extension of
the cortical bone into the stalk of
the lesion.
Notice the lytic peripheral part
with subtle calcifications.
This part corresponds to a zone of
high SI on T2-WI with FS on the
right.
This represents a thick cartilage
cap.
This is an example of progression
of an osteochondroma to a
peripheral chondrosarcoma.

134. MALIGNANT TRANSFORMATION
Radiographic features that should raise the suspicion of malignant
transformation on plain radiographs or CT include:
Growth of osteochondroma in skeletally mature patient
Irregular or indistinct surface of lesions
focal lucent regions in interior of lesions
erosion or destruction of adjacent bone
presence of soft tissue mass with scattered or irregular calcifications

135. OTEOID OSTEOMA
Small osteolytic lesion (up to 1.5 cm) with or without central
calcification.
Surrounded by a prominent zone of reactive sclerosis due to a
periosteal and endosteal reaction, which may obscure the central
nidus.
In juxta-articular localisation, the reactive sclerosis may be absent.
Localisation: femur, tibia, hands and feet, spine (arch).
Axial imaging for differentiation from Brodie abscess, osteoblastoma,
stress fracture

136. Here the reactive sclerosis is the
most obvious finding on the X-ray.
There is reactive sclerosis with a
nidus that is barely visible on the
radiograph (blue arrow), but
clearly visible on the CT (red
arrows).
CT scan is usually very helpful in
detecting the nidus and
differentiating osteoid osteoma
from other sclerotic lesions like
osteoblastoma, osteomyelitis,
arthritis, stress fracture and
enostosis.
MRI also may detect the nidus,
combined with abundant bone
marrow and soft tissue edema.

137. In most cases of osteoid osteoma
the radiographic appearance is
determined by the reactive
sclerosis.
In some cases however the
osteolytic nidus can be visible on
the radiograph (figure).

138. Osteoma consists of densely
compact bone.
It is most commonly located in the
outer table of the neurocranium or
in a paranasal sinus.

139. OSTEOMYELITIS
Osteomyelitis is a mimicker of various benign and malignant bone
tumors and reactive processes that may be accompanied by reactive
sclerosis.
Acute osteomyelitis is characterised by osteolysis.
Sclerosis is usually the most prominent finding in subacute and
chronic osteomyelitis.
A periosteal reaction with or without layering may be present.
Sometimes a more solid periosteal reaction is present combined with
cortical thickening and broadening of the bone.

140. an image of a patient with chronic
osteomyelitis.
Centrally there is an ill-defined
osteolytic area.
The major part of the lesion
consists of reactive sclerosis.

141. OSTEOSARCOMA
2nd most common primary bone tumor and highly malignant.
50% around the knee.
Presentation: pain, mass, pathologic fracture.
Sclerosis is present from either tumor new bone formation or reactive
sclerosis.
Age: most commonly seen in 10-25 years, but may occur in older patients.
Plain films typically reveal lesions with moth-eaten or permeative pattern of
the transition zone with irregular cortical destruction and an interrupted
periosteal reaction with soft tissue extension.
A periosteal reaction known as Codman's triangle appears as tumor elevates
periosteum from underlying bone. Cortical soft tissue extension may
produce radiating spicules of bone called sunray appearance.

143. images of an osteosarcoma in the
right femur.
It is barely visible within the bone,
but an agressive periostitis is seen
(arrow).
Continue with the MR-images.

144. The sagittal T1WI and Gd-
enhanced T1W-image with fatsat
show a large tumor mass
infiltrating a large portion of the
distal femur and extending
through the cortex into the soft
tissues.

145. PAROSTEAL OSTEOSARCOMA
Parosteal osteosarcoma is a sarcoma that has it's origin on the
surface of the bone.
It grows primarily into the surrounding soft tissues, but may also
infiltrate into the bone marrow.
It is most commonly located on the posterior side of the distal meta-
diaphysis of the femur.
Ossification in parosteal osteosaroma is usually more mature in the
center than at the periphery. This is opposed to myositis ossificans
which may present very close to the cortical bone, but maturation
develops from the center to the periphery.

146. Radiograph.
Small homogeneous mass adjacent
to the cortex of the diaphysis of
the femur
MRI
Juxtacortical mass with
enhancement of the periphery.
Bone marrow and cortiical bone
are otherwise normal.
Notice absence of reactive changes
around the lesion.

147. Paget disease is a chronic disorder
of unknown origin with increased
breakdown of bone and formation
of disorganized new bone.
The most common appearance is
the mixed lytic-sclerotic.
In this case we see the
pathognomonic triad of bone
expansion, cortical thickening and
trabecular bone thickening in the
mixed lytic and sclerotic phase of
Paget's disease of right hemipelvis.

148. Myositis ossificans
Here a patient with a mineralized
mass in the soft tissues.
Notice that the mineralization is
predominantly in the periphery of
the mass and that there is a lucent
zone between the mass and the
cortical bone.
Contrast-enhanced T1-weighted
MR image demonstrates
heterogeneous enhancement of
the mass with extensive
surrounding edema.
This is consistent with the
diagnosis of a reactive process like
myositis ossificans.

149. Stress fractures occur in normal
(fatigue fractures) or metabolically
weakened (insufficiency fractures)
bones.
Usually stress fractures are easy to
recognize.
Uncommonly it can be difficult to
differentiate a stress fracture from
a pathologic fracture, that occurs
at the site of a bone tumor.

150. Uncommonly it can be difficult to
differentiate a stress fracture from
a bone tumor like an osteoid
osteoma or from a pathologic
fracture, that occurs at the site of
a bone tumor.

152. an example of a patient with a
stress fracture of the distal fibula.
Coronal MR image demonstrates
subtle low intensity line
representing the fracture.
Differential diagnosis based on the
periosteal reaction and the
extensive edema:
Osteomyelitis
Eosinophilic granuloma

153. Posttraumatic calcifications
Here a patient with a juxtacortical
sclerotic mass of the proximal
humerus (left).
This proved to be a reactive
calcification secondary to trauma.
Notice the resemblance to a
juxtacortical mass in another
patient (right), which was a biopsy
proven parosteal osteosarcoma.
This shows that differentiating a
tumor from a reactive proces scan
be quite difficult in some cases.
When a reactive process is more
likely based on history and
imaging features, follow-up is
sometimes still needed.

154. Subungual exostoses
Subungual exostoses are bony
projections which arise from the
dorsal surface of the distal
phalanx, most commonly of the
hallux.
These lesions are not
osteochondromas, but consist of
reactive cartilage metaplasia.
The radiographic appearance and
location are typical.

155. Nora's lesion
Here two patients with a bizar
parosteal osteochondromatous
proliferation (BPOP), also called
Nora's lesion.
This benign reactive process is
most commonly found adjacent to
the cortex of phalanges of hands
or feet (75%).
The cortical bone and bone
marrow compartment are not
involved.
Rapid growth of the mineralized
mass is not uncommon.

156. CHONDROSARCOMA
Malignant bone tumor that produces cartilage.
 usually central and metaphyseal
Typical presentation: large osteolytic lesion with scalloping of the inner
cortex and rings-and-arcs or popcorn calcifications in an elderly person with
a painful swelling.
Secundary chondrosarcoma is most common and arises from enchondroma
or osteochondroma.
Patients with multiple enchondromas like in Ollier's disease and Mafucci's
syndrome are at risk.
Low grade tumor can usually not be differentiated from enchondroma based
on imaging findings alone.
High grade tumor may present as aggressive ill-defined lesion with
extention into the soft tissues.

157. CHONDROSARCOMA
On plain radiographs the differential diagnosis with enchondroma can
be difficult.
Think of chondrosarcoma instead of enchondroma if there is one or
more of the following features:
 Elderly patient
 Location in long bones
 Size > 5 cm
 Uptake on bone scan
 Endosteal scalloping on MRI
 Cortical involvement
 Early enhancement on dynamic contrast enhanced series
Disappearane of calcifications in a pre-existing enchondroma should
raise the suspicion of malignant transformation.

159. The differential diagnosis on the
plain radiographs in all these three
cases is enchondroma.
Additional MR imaging and bone
scintigraphy may be helpful to
make the diagnosis of
chondrosarcoma more or less
likely.