This document summarizes information about evaluating benign bone lesions on radiographs. It discusses diagnostic criteria including age, location, margins, and matrix. Common benign bone tumors are described such as simple bone cysts, aneurysmal bone cysts, osteoid osteoma, and enchondroma. Location is an important factor, for example enchondromas often occur in hands and feet. Classification is discussed based on matrix type such as cystic, osseous, chondroid, and fibro-osseous lesions. Radiologic features of specific tumors and mimics are presented. The conclusion emphasizes that attention to age, location, and radiographic features helps narrow the differential diagnosis.
2. INTRODUCTION
Primary benign bone tumors are more common than
malignancies in children and adolescents.
Patient age and lesion location are two critical
factors when evaluating for a bone tumor.
Radiography is the mainstay and is a cost-effective
imaging modality. Cross-sectional imaging is helpful in
tissue characterization and for evaluating the extent
of the lesions.
3. DIAGNOSTIC CHECKLIST TO EVALUATE BONE
LESIONS ON RADIOGRAPHS
Age
Location
Number of lesions
Lesion matrix
Margin features
Presence or absence of periosteal reaction
Presence or absence of extraosseous extension
4. Matrix or tissue Benign tumors
Cystic lesions Unicameral (simple) bone cyst, aneurysmal bone cyst
Osseous matrix Enostosis, osteoma, osteoid osteoma, osteoblastoma
Chondroid matrix Enchondroma, chondroblastoma, chondromyxoid fibroma,
osteochondroma, juxtacortical chondroma
Fibro-osseous Nonossifying fibroma, fibrous dysplasia, osteofibrous dysplasia
Fat Lipoma
Vascular malformations Hemangioma
Giant cell tumors Giant cell tumor
Others Langerhans cell histiocytosis
CLASSIFICATION ACCORDING TO MATRIX OR
TISSUE TYPE
8. CENTRIC ECCENTRIC CORTICAL JUXTACORTICAL
Simple bone cyst,
eosinophilic
granuloma,
fibrous dysplasia,
enchondroma
ABC,Chondroblastoma,
chondromyxoid
fibroma,
giant cell tumor,
osteoblastoma
Nonossifying
fibroma,
osteoid
osteoma
Osteochondroma,
juxtacortical
chondroma
RADIOLOGIC APPROACH TO BENIGN BONE
TUMORS—LOCATION IN THE LONG BONES
9. RADIOLOGIC APPROACH TO BONE TUMORS
AND TUMORLIKE CONDITIONS—POLYOSTOTIC
LESIONS
Fibrous dysplasia
Enchondroma
Eosinophilic granuloma
Hyperparathyroidism
Infection
10. CYSTIC LESIONS: SIMPLE BONE CYST
Location: Intramedullary,
metaphysis of long bones,
abutting the growth plate;
most commonly in proximal
humerus and proximal femur
Radiograph shows well-demarcated
lucent lesion in the proximal
humerus with endosteal scalloping:
simple bone cyst.
Radiograph shows fallen fragment
sign : after pathologic fracture.
11. Sagittal STIR MR image shows internal
trabeculation in humeral simple bone
cyst, which can happen after fracture
Axial short inversion time inversion-
recovery (STIR) magnetic resonance
(MR) image through right proximal
femur shows high signal intensity
without fluid-fluid levels.
12. CYSTIC LESIONS: ANEURYSMAL BONE CYST
Eccentric in metaphysis of long
bones (50%–60%), spine and
sacrum (20%–30%)
Axial MRI IMAGE showing fluid-fluid levels Radiograph shows sharply defined, expansile radiolucent
lesion with thin mineralized margins in proximal tibia.
13. BONE-FORMING TUMORS: ENOSTOSIS
Focus of cortical bone located in the cancellous bone.
Location: Pelvis, long bones, ribs, spine
Frontal radiograph (left) and axial bone algorithm CT image (right) through the proximal femur
demonstrate a well-circumscribed dense lesion in the medullary cavity : enostosis.
14. BONE FORMING TUMORS: OSTEOMA
Osteomas are benign lesions
consisting of mature bone
tissue.
Location: PNS (75% overall),
skull vault, and mandible
Multiple osteomas can be seen
in Gardner syndrome.
Smooth marginated radiodense lesion
Radiograph shows right frontal osteoma
Axial CT image shows ossified mass in right ethmoid sinus:
osteoma
15. BONE-FORMING TUMORS: OSTEOID
OSTEOMA
Location: Cortical diaphyseal location (65%–70%),
commonly in femur, spine -10%
Classically manifests with nocturnal pain
Relieved by aspirin
16. CT is the modality of choice for confirmation, as well as
localization of nidus, and helps to guide ablation.
Calcaneal osteoid osteoma : Lateral radiograph (A) and sagittal bone algorithm CT image (B)
show reactive mineralization around the lucent central nidus, which is less than 2 cm in
diameter (osteoblastoma if nidus is >2 cm)
17. BONE-FORMING TUMORS: OSTEOBLASTOMA
Location: Spine, in particular posterior
elements (40%–55%); metaphysis and
distal diaphysis of long bones (26%)
Insidious dull pain that gets worse at
night
Minimal response to salicylates
Axial bone algorithm CT image shows expansile
lucent lesion (>2 cm in size) with rim of
mineralization: thoracic spinal osteoblastoma.
18. CARTILAGE-FORMING TUMORS: ENCHONDROMA
Location: Medullary cavity
of tubular bones
Pathogenesis: Arise from
growth plate cartilage
and/or chondrocytes that
subsequently proliferate and
slowly enlarge and are
composed of mature hyaline
cartilage
Radiographs show expansile lucent lesion in the middle phalanx with
cortical thinning: enchondroma with pathologic fracture.
19. OLLIER DISEASE
Nonhereditary, sporadic, skeletal disorder
characterized by multiple
enchondromas that are principally located
in the metaphyseal regions
If associated soft-tissue hemangiomas, it is
termed Maffucci syndrome.
Radiograph shows vertical streaks of lucencies (columnar
configuration) in metaphysis of long bones, extending to
the epiphysis
20. CARTILAGE FORMING TUMORS:
CHONDROBLASTOMA
Location: More than 75% in long bones, epiphyseal in origin,
which often extends to metaphysis
Pathologic finding: They are composed of chondroblasts.
Calcium deposition surrounding the polyhedral chondroblasts
has been described as a "chicken-wire calcification” pattern.
22. CARTILAGE FORMING TUMORS:
OSTEOCHONDROMA
Any bone that develops from preformed cartilage
(enchondral ossification) may develop an
osteochondroma.
The lesion is composed of cortical and medullary bone
protruding from and continuous with the underlying bone.
24. DIAPHYSEAL ACLASIS
Also known as hereditary
multiple exostoses
AD inheritance
90% have positive family
history for multiple
exostoses.
There is symmetric widening of metaphyses with multiple small and
large multilobulated exostoses arising from normal underlying
bone: diaphyseal aclasis.
25. FIBRO OSSEOUS LESIONS: NON
OSSIFYING FIBROMA
A larger version (>3
cm) of a fibrous
cortical defect
Radiographs show sharply demarcated, multilobulated, asymmetrical,
cortically based lucent lesion with a thin mineralized rim: distal tibial
nonossifying fibroma.
26. MULTIPLE NONOSSIFYING FIBROMA: JAFFE-
CAMPANACCI SYNDROME
Jaffe-Campanacci is a rare syndrome
characterized by the association of
café au lait spots, axillary freckles,
and multiple nonossifying fibromas of
the long bones and jaw, as well as
some features of type 1
neurofibromatosis.
The risk for pathologic fracture is more
than 50% because of substantial
cortical thinning of the weight-bearing
bones.
27. FIBRO-OSSEOUS LESIONS:FIBROUS DYSPLASIA
Non neoplastic tumor like congenital process, manifesting as a
localized defect in osteoblastic differentiation and maturation,
with replacement of normal bone with large fibrous stroma
and islands of immature woven bone
CT images show ground-glass matrix; well-circumscribed; no periosteal reaction: fibrous dysplasia.
28. Treatment: None, as the bone
lesions usually do not progress
beyond puberty. Treat if
complicated by pathologic
fracture. If mass effect is severe,
then surgical decompression.
Risk of malignant transformation:
1% in monoostotic form;
4% in polyostotic form
CT images show bowing deformity, “shepherd’s crook” deformity,
of femoral neck.
29. FIBRO-OSSEOUS LESIONS:
OSTEOFIBROUS DYSPLASIA
Location: Tibial
diaphysis most
common (80%), mainly
the anterior cortex
Pathologic finding:
There are randomly
distributed lamellated
bone spicules on a
background of fibrous
stroma.
Frontal (A) and lateral (B) radiographs of tibia and fibula demonstrate a
multiloculated lucent ground-glass lesion with a mineralized margin and
cortical expansion; note tibial bowing and pseudoarthrosis after a pathologic
fracture ; no periosteal reaction.
30. GIANT CELL TUMOR
Also known as osteoclastoma; rare in skeletally immature
patients (80% of cases occur between 20 and 50 years;
fewer than 3% of cases occur before the age of 14 years)
Location: Commonly around knee and distal radius
Pathogenesis: Overexpression in RANK-RANKL (receptor
activator of nuclear factor kappa-B ligand)
signaling pathway with resultant overproliferation and/or
recruitment of osteoclasts
31. Radiographs show well-defined eccentric epimetaphyseal lesion; occurs after growth plate closure; abuts
articular surface; nonmineralized margin; note pathologic fracture.
32. Isointense to skeletal muscle on T1-weighted (A) and heterogenously hyperintense on T2-weighted
(B) MR images: tibial giant cell tumor.
33. INTRAOSSEOUS LIPOMA
Location: Most frequently in calcaneus; metaphysis of long bones
Radiograph shows radiolucent bone lesion with well-
defined margins and internal mineralization.
CT image shows fat-containing well-defined lesion with
central ossification.
34. VASCULAR MALFORMATIONS: HEMANGIOMA
Location: Most frequently seen in the vertebrae or skull.
Vertebral hemangiomas are actually venous malformations.
Sagittal T1-weighted and T2-weighted MR images demonstrate
a circumscribed T1- and T2- hyperintense lesion in the body of
thoracic vertebra: classic MR appearance of hemangioma.
CT image shows well-circumscribed
hypoattenuating lesion with coarse vertical
trabeculae polka-dot appearance.
38. TUMOR MIMICS: EOSINOPHILIC GRANULOMA
Location: Skull (50%),
mandible, ribs, femur, pelvis
Pathologic finding: abnormal
proliferation of Langerhans
cells with an abundance of
eosinophils, lymphocytes,
and neutrophils.
These cells produce PGs,
which result in medullary
bone resorption.
Skull radiograph (left) and axial bone algorithm CT image (right) demonstrate a punched-
out lucent lesion without a mineralized rim; double-contour or bevelled-edge
appearance is due to greater involvement of the inner than the outer table.
39. TUMOR MIMICS: INFECTION (BRODIE ABSCESS)
Intraosseous abscess
related to focus of
subacute pyogenic
osteomyelitis
MC organism Staph.aureus
Location: Metaphysis of
long bones
MC- proximal or distal tibia
Radiograph shows lucent lesion with mineralized rim in the metaphysis of distal tibia
MR image: penumbra sign indicates a rim of vascularized granulation tissue lining of
the abscess cavity with higher signal intensity than that of the main abscess fluid
collection on T1-weighted images.
40. BROWN TUMOR IN HYPERPARATHYROIDISM
Aka osteitis fibrosa
cystica; one of the
manifestations
of hyperparathyroidism,
which represents a
reparative cellular
process rather than a
neoplastic process.
Radiographs show well-defined,
purely lucent lesions; thinning and
expansion of cortex; pathologic
fracture (white arrow); subperiosteal
bone resorption on radial aspect of
phalanges .
41. CONCLUSION
Primary benign bone tumors are more common than
malignancies in children and adolescents.
By paying attention to the age of the patient, location
of the lesion, and radiographic characteristics, the
radiologist can narrow the differential diagnosis,
which helps to guide clinical management, preventing
unnecessary patient anxiety and medical intervention.
Treatment options: None if asymptomatic; intralesional steroids for large cysts; surgery with curettage and bone grafting
Treatment options: Curettage and bone grafting, with a recurrence rate of 12%–30%1
Treatment: No-touch lesion
Treatment: Excise only if they cause complications (eg, mucocele) or mass effect (functional or cosmetic impairment).
Biopsy is often required to differentiate it from osteosarcoma (if the lesion involves long bone).
Treatment options: Radical surgical excision; preoperative embolization to reduce bleeding risk; percutaneous ablation
Treatment options: None for small incidental lesions; marginal and/or wide resection for large symptomatic lesions; sarcoma follow-up if histologic finding shows low-grade chondrosarcoma.
25%–30% risk of chondrosarcoma at 40 years2
Treatment: Watchful waiting; biopsy if there is growth after the adjacent growth plate closure; remove exostoses causing complications and if cartilage cap is more than 1.5 cm (approximately 3%–5% risk for developing chondrosarcoma4)
Pathologic finding: Mature adipocytes without admixed hematopoietic tissue or bone trabeculae
Complications: Pathologic compression fracture; epidural extension with cord compression
Treatment: None if asymptomatic
Treatment: Usually undergoes spontaneous resolution; if symptoms persist, excision and curettage
Treatment options: Surgical curettage, bone grafting and antibiotic therapy
