Osteochondroma is a benign bone tumor that projects from the external surface of bones. It consists of a bony projection capped with cartilage. The majority of osteochondromas are solitary lesions that present during childhood in long bones like the femur or humerus. Multiple or hereditary osteochondromas can occur as part of genetic syndromes. Osteochondromas are usually asymptomatic but can cause pain or neurological symptoms from local effects. Malignant transformation is rare in solitary lesions but higher in hereditary forms. Imaging plays a key role in diagnosis and follow up, with plain radiographs, CT and MRI used to characterize lesions. Surgical excision is reserved for symptomatic osteochondromas.

1. OSTEOCHONDROMA
DR. MAHESH CHAUDHARY
PHASE-A RESIDENT
RADIOLOGY & IMAGING
BSMMU

2. DEFINITION
• Other names:
Cartilage caped exostosis
Osteo-cartilaginous exostosis
• Osteochondroma is a bony exostosis
projecting from the external surface of a bone
• It is usually has a hyaline lined cartilaginous
cap
• The cortex and spongiosa of the lesion merge
with that of the parent bone

3. GENERAL CONSIDERATIONS
• When the lesion is seen in a single bone , it is
called solitary osteochondroma
• If two or three bones are involved , with no
familial history , the condition is known as
multiple ostechondromas
• Widespread ostechondromas are associated with
a positive familial history, and the condition is
known as Heriditary Multiple Exostosis
(diaphyseal aclasia)
• Usually occurs in bones preformed in cartilage

4. INCIDENCE
• Most common skeletal growth tumor
• Approximate incidence is 50% of all benign bone
tumors
• Male : Female ratio 1:1 (?2:1)
• Most are encountered in childhood and adolescence
• Usually follows minor trauma
• Many cases may not be diagnosed due to the silent
nature of the disease

5. PATHOPHYSIOLOGY
• Osteochondromas are developmental lesions rather than true
neoplasms
• These lesions result from the separation of a fragment of epiphyseal
growth plate cartilage, which subsequently herniates through the
periosteal bone cuff
• The mechanism likely results from the remodeling during growth of the
long bone.
• Persistent growth of this cartilaginous fragment and its subsequent
enchondral ossification (maturation) result in a subperiosteal osseous
excrescence with a cartilage cap that projects from the bone surface.
• Osteochondromas enlarge from growth at the cartilage cap
• After adolescence and skeletal maturity, osteochondromas usually
exhibit no further growth.

6. The development of an osteochondroma, beginning with
an outgrowth from the epiphyseal cartilage
 Histology:
•Covered by thin layer of periosteum.
•Binucleate chondrocytes in lacunae.
•Contains hyaline cartilage, bony
tissue & normal bone marrow particle.

7. LOCATION
(common)
BONE PERCENTAGE
Femur 34
Humerus 18
Tibia 15
Pelvis 8
Scapula 5
Ribs 3

8. UNCOMMON SITES (17%)
• Metacarpals
• Condylar process of the mandible
• Base of the skull
• Talus
• Calcaneus
• Spine
• Distal end of the clavicle

9. TYPICAL INVOLVEMENT
• Spine lesions are typically located at the secondary
ossification centres
• Scapular involvement is seen at
1. Inferior angle
2. Superior angle
3. Coracoid process
• Pelvic involvement is most commonly near the
1. Anterior superior iliac spine
2. Ischiopubic synchondrosis
• Large enough lesions are termed as cauliflower
exostosis
• Anterior aspects of the ribs are most commonly involved

10. TYPES
TYPE SESSILE PEDUNCULATED
Incidence Uncommon Common
Location Proximal humerus
and scapula
Knee , hip and ankle
Appearance Flat plateau like
stalk producing a
broad based
protuberance
• Elongated bony
stalk merging with
the host bone
• The hyaline cap is
lobulated giving its
appearance

11. SESSILE VARIANT
Solitary
Osteochondroma
Lateral radiograph of a
sessile
osteochondroma of the
distal femur.

12. PEDUNCULATED VARIANT
Solitary osteochondroma
Lateral radiograph of a
pedunculated
osteochondroma of the
distal femur.

13. CLINICAL FEATURES
• Most are asymptomatic
• Symptoms arise as a result of their
1. Location: Tendon or nerve irritation
2. Size
3. Pressure effects on adjacent structures
• Usual complaint is hard palpable mass

14. COMPLICATIONS
COMPLICATION PERCENTAGE
Fracture 7
Deformity 23
Vascular injury 7
Neurological compromise 10
Adventitious bursae formation 27
Mechanical irritation 10
Malignancy ( Solitary / HME ) <1 , > 10

15. RADIOLOGICAL
INVESTIGATIONS

16. X - RAY
PENDUNCULATED VARIANT
• Knee is the most common location
• Metaphysis is the common site of involvement
• Lesion has a slender stalk with a cartilaginous
dome
• The cartilage may show dense amorphous /
spotty calcification
• COAT HANGER EXOSTOSIS : The lesion
invariably point away from the joint due to muscle
pull

17. X - RAY
SESSILE VARIANT
• Creates a broad based exostosis lacking an elongated
projection
• Causes a long asymmetric elongation of the bone
• Amorphous , spotty calcification is absent
• Occur at the metaphyseal – diaphyseal region

18. ULTRASONOGRAPHY
• Ultrasonography can be applied to analyze
the cartilaginous cap of an osteochondroma.
• The cap appears as a hypoechoic layer
covering a hyperechoic underlying bone.
• Ultrasonography is also valuable in the
diagnosis of bursitis and other complications
associated with osteochondromas, such as
arterial or venous thrombosis, as well as
aneurysm and pseudoaneurysm formation.

19. X-ray AP of left thigh
USG of the left thigh above the lump

20. MRI
• MR imaging is the best radiologic imaging method
evaluating hyaline cartilage cap.
• The high water content in non mineralized areas of the
cartilage cap has intermediate to low signal intensity on
T1-weighted images and high signal intensity on T2-
weighted images.
• Mineralized areas in the cartilage cap had low signal
intensity on T1 and T2-weighted images
• In young patients with active growth and maturation from
normal enchondral ossification in the cartilage cap may be
marked heterogeneity both T1-weighted images and T2-
weighted images because of the mixture of non
mineralized and mineralize cartilage tissues.

21. Selected T1 and T2 weighted images shown above demonstrate a
broad based exophytic lesion of bone. The marrow space of the
bone and the lesion are contiguous. There are areas of T2
brightening at the periphery of the lesion, but without frank invasion
of the surrounding tissues.

23. C.T. SCAN
• Allows optimal demonstration of the pathognomonic cortical
and medullary continuity of the lesion and parent bone
• Mineralization in the cartilage cap allows a correct CT
measurement
• However, it can be very difficult to correctly measure the
thickness of a totally nonmineralized cartilage cap because it
cannot be easily differentiated from surrounding muscle or
bursa.
• Cartilage cap thickness greater than 1 to 2 cm in adults and 2
to 3 cm in growing children suggests malignant
transformation

24. CT through the
proximal tibia
showing a tibial
osteochondroma
(arrow) causing
marked thinning of
the adjacent fibula
(arrowhead).

25. Multiple osteochondromatosis. Nonenhanced, axial computed
tomography (CT) scan through the pelvis. Note the fragmentation of the
osteochondroma and the considerable soft-tissue mass.

26. MALIGNANT TRANSFORMATION
CLINICAL
1. Growth of lesion after skeletal maturity
2. Pelvis / shoulder (mostly sessile variety)
3. < 1 % in solitary , > 10% in HME
4. Increasing mass and pain at the site of
lesion in absence of fracture, bursitis or
nerve compression

27. MALIGNANT TRANSFORMATION
RADIOLOGICAL
1. Visualized cartilage cap measures >2 cm in
adults and >3 cm in children
2. Bone destruction
3. Dispersed calcification in cartilaginous cap
4. Soft tissue mass
5. Altered appearance on sequential studies
6. Increase uptake in bone scan (Unrelaible)

28. Associations and
Syndromes
Hereditary multiple exostoses (diaphyseal
aclasis)
• Autosomal dominant condition
• Short stature
• Multiple osteochondromas
• Asymmetric growth at the knees and ankles
• Risk of malignant degeneration is about 10% & often around the
hip

29. Dysplasia epiphysealis hemimelica
(DEH, Trevor’s disease)
• Osteochondromas arising in the epiphyses
• Involve the joint
• Lesions restricted to one side of the body–either left or right
• May be multiple lesions in a single limb
• Primarily involves one side of an epiphysis
• Medial side is affected twice as often as the lateral side
• Usually occurs in infants or young children

30. Enchondromatosis (ollier disease)
Nonhereditary abnormality in which multiple
enchondromas
are present. Many lesions become stable at puberty. Risk
of malignant transformation to chondrosarcoma is 25%.
Radiographic Features
• Multiple radiolucent expansile masses in hand and feet
• Hand and foot deformities
• Tendency for unilaterality

31. Imaging Differential diagnosis
Hands- Bizarre parosteal osteochondromatous proliferation
(BPOP)
• Does not have cartilaginous cap.
• Seen in hands and feet.
• Continuity between the lesion
and underlying bone is not found
• Bony growth projecting into soft tissues .

32. Humerus - Supracondylar spur :
• Anatomical variant present in ~1% of the population
• Usually asymptomatic
• Considered if patients present with
symptoms of median nerve compression
and there is no pathology on imaging of
the carpal tunnel.
 a bony spur projecting antero-
medially from humeral metadiaphysis
(towards elbow joint)

33. Osteochondromatous
Variants
Dysplasia epiphysealis hemimelica
Subungual exostosis
Turret exostosis
Traction exostosis (at tendinous attachments)
Bizarre parosteal osteochondromatous
proliferation = Nora lesion
Florid reactive periostitis

34. Treatment
No treatment necessary for asymptomatic
osteochondromas (Observation)
If the lesion is causing pain or neurologic symptoms
due to compression, it should be resected at the base
None of the cartilage cap or perichondrium should be
left in the resection bed or recurrence can occur.
As long as the entire cartilage cap is removed there
should be no recurrence
Patients with many large osteochondromas should
have regular radiographic screening exams for the early
detection of malignant transformation

35. REFRENCES
• BOOKS:
1. Text book of Radiology & Imaging: David
Sutton
2. Essentials of Skeletal Radiology: Yochum and
Rowe
3. Bone and Joint Imaging : Resnick
• WEB:
1. http://radiopaedia.org/articles/osteochondroma
2. http://www.learningradiology.com/archives2007/COW
%20243-
Osteochondroma/osteochondromacorrect.html

36. THANK YOU…
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