The document provides an overview of musculoskeletal tumors according to the WHO classification system. It then focuses on osteochondroma tumors, describing them as benign bone tumors consisting of a bony base with a cartilage cap projecting from the bone. Osteochondromas are most common in long bones and typically present as asymptomatic bony masses. For solitary osteochondromas, radiographs are usually diagnostic but additional imaging may be needed to assess thickened cartilage caps or other concerning features that could indicate malignant transformation.

1. osteochondroma
Rso orthopaedics
Dr. ravi Diwakar
5/4/21
Nscb mch Jabalpur

2. Overview of
musculoskeletal tumors

3. World Health Organization (WHO) classification of bone tumors is the
most widely used pathologic classification system for such disorders.
• Chondrogenic tumors
• Osteochondroma M9210/0
• Chondromas M9220/0
• enchondroma
• periosteal chondroma
• chondromyxoid fibroma M9241/0
• Chondroblastoma M9230/0
• chondrosarcoma (grades I-III) including
primary and secondary variants
and periosteal chondrosarcoma M9220/3
• dedifferentiated chondrosarcoma M9243/3
• mesenchymal chondrosarcoma M9240/3
• clear cell chondrosarcoma M9242/3
Osteogenic tumors
• Osteoma M9180/0
• osteoid osteoma M9191/0
• Osteoblastoma M9200/0
• low-grade central osteosarcoma M9187/3
• conventional osteosarcoma M9186/3
• telangiectatic osteosarcoma M9183/3
• small cell osteosarcoma M9185/3
• parosteal osteosarcoma M9192/3
• periosteal osteosarcoma M9193/3
• high-gradesurface osteosarcoma M9194/3

4. Fibrogenic tumors
• desmoplastic fibroma of bone M8823/0
• fibrosarcoma of bone M8810/3
Fibrohistiocytic tumors
• non-ossifying fibroma and benign
fibrous histiocytoma of bone M8830/0
Ewing sarcoma
• Ewing sarcoma M9260/3
Hematopoietic neoplasms
• plasma cell myeloma M9732/3
• solitary plasmacytoma of bone
M9734/3
Osteoclastic giant cell-rich tumors
• giant cell lesion of the small bones
• giant cell tumor of bone M9250/1
Notochordal tumors
• benign notochordal cell tumor
• chordoma
Vascular tumors
• Hemangioma M9120/0
• epithelioid hemangioma M9125/0
• epithelioid hemangioendothelioma
M9133/1
• Angiosarcoma M9120/3
Myogenic, lipogenic, and epithelial
tumors
• Leiomyosarcoma M8890/3
• Lipoma M8850/0
• Liposarcoma M8850/3
• adamantinoma

5. Tumors of undefined neoplastic
nature
• aneurysmal bone cyst
• simple bone cyst
• fibrous dysplasia
• osteofibrous dysplasia
• Langerhans cell histiocytosis
• Erdheim-Chester disease
• chondromesenchymal hamartoma
• Rosai-Dorfman disease
Undifferentiated high-grade
pleomorphic sarcoma
• undifferentiated high-grade
pleomorphic sarcoma

6. OSTEOCHONDROMA
• Described by Sir Astley Cooper
• An osteochondroma, or osteocartilagenous exostosis, is one of the most
common benign bone tumors.
• WHO defines “ osteochondroma as a cartilage capped bony projection
arising on the external surface of bone containing a marrow cavity that is
continuous with underlying bone”.
• It consists of a bony base or stalk with a cartilage cap that projects from the
normal bone away from a nearby joint.
• A fibrous tissue capsule or bursa typically covers the cartilage surface.
Osteochondromas may develop from proliferation of cartilage-forming
periosteal cells or from a defect in the fibrous tissue surrounding a physis
and therefore likely represent a developmental disorder instead of a
neoplasm.

7. • Common locations include the metaphysis of the proximal tibia, distal
femur, distal tibia, distal fibula, proximal femur, and proximal
humerus. They also can develop from flat bones of the pelvis and
scapula.
• Osteochondromas commonly present as solitary or multiple firm,
fixed, asymptomatic bony masses. Most affected patients have a
solitary osteochondroma, but some individuals have a hereditary
disorder that causes multiple osteochondromas. This disorder,
multiple hereditary exostoses (MHE), is transmitted as an autosomal
dominant trait with a high degree of penetrance and can cause
marked skeletal deformity and disability

11. • Most patients recognize the presence of multiple lesions before 20
years of age. Severely affected people develop considerable skeletal
deformity
• Any further enlargement after the end of the growth period is
suggestive of malignant transformation

12. Epidemiology
• Average age of clinical presentation is between 10 and 30.
• These tumors account for 10%-15% of all bone tumors, while
representing 36% of all non-malignant bone tumors Solitary
osteochondroma occur equally in males and females, while multiple
osteochondroma affects males more than females, approximately
1.6:1.
• Metaphysis during period of rapid skeletal growth
• IN ANY BONE PREFORMED IN CARTILAGE
• MC distal femur
prox tibia
prox humerus
• Rarely in joint

13. Etiology
• A focal herniation of the medial or lateral component of the
epiphyseal plate results in the formation of an aberrant, cartilage-
capped, eccentric small bone.
• Several theories have been proposed to explain this phenomenon
• Virchow in 1891 put forth the physeal theory, according to which a
portion of the physeal cartilage becomes separated from the parent
tissue, rotates 90 degrees, and grows in a direction transverse to the
long axis of the bone.
• However, he did not provide an explanation for the separation and
rotation of the detached physeal cartilage.

14. • In 1920, Keith proposed that the cause was a defect in the
perichondral ring surrounding the physis,
• Müller in 1913 theorized that the exostoses were produced by small
nests of cartilage derived from the cambium layer of the periosteum.
By producing osteochondroma using physeal cartilage
transplantation, D’Ambrosia and Ferguson provided support for the
physeal plate defect theory.
• Current thought is that the cause is misdirected growth of a portion
of the physeal plate, with lateral protrusions causing the development
of the eccentric cartilage-capped bony prominence.

15. Pathophysiology
• Solitary osteochondroma- Literature suggests that solitary
osteochondromas may result from a developmental abnormal rather
than representing a true neoplasm.
• The proposed hypothesis is that a fragment of the growth plate
herniates through the periosteum, which then continues to grow,
resulting in either a sessile or pedunculated lesion most commonly in
the region of the metaphysis.
• The separation of the growth plate fragment can occur either
spontaneously (primary osteochondroma), or secondary resulting from
irradiation, surgery, or fractures (secondary osteosarcoma)

17. • Hereditary multiple exostoses- a/with loss-of-function type of
mutation in the tumor suppressor genes EXT1 and EXT2 that are
responsible for the synthesis of heparan sulfate proteoglycans (HSPG)
which results in HSPG deficiency and subsequent development of
multiple osteochondroma.
• The importance of HSPG in the development of osteochondromas lies
in its ability to interact with the bone morphogenetic proteins (BMPs)
that have an essential role in the regulation of bone and cartilage
formation
• In general, patients with EXT1 mutations are more severely affected
(more osteochondromas and more severe osseous deformities).

20. Histopathology
• Macroscopic gross external examination:-
• Grossly, osteochondroma is a lobulated sessile or pedunculated lesion
arising from the surface of the bone with a somewhat cauliflower-like
appearance.
• The cartilage cap has a shiny glistening bluish to grey appearance.
• The thickness of the cartilage cap of 1 to 3 cm is considered normal in
children due to the ongoing growth process.
• Cap thickness exceeding 2 cm in an adult should raise suspicion
for malignancy. Varying degrees of mineralization may be present
within the cartilage cap.

22. This is an osteochondroma cut into three sections. A bluish-white
cartilagenous cap overlies the bony cortex. These are probably not true
neoplasms, but they are a mass lesion that extends outward from the
metaphyseal region of a long bone.

24. • Microscopic examination:-
Starting from the periphery, the cartilage cap that covers the tumor has a
similar histological feature to the growth plate. At the junction of the
cartilaginous cap and the underlying bone, evidence of endochondral
ossification is visible.

27. History and Physical
• Solitary osteochondromas are usually asymptomatic lesions
discovered incidentally on radiographs obtained for non-contributory
symptoms.
• Symptomatic lesions may be secondary to fracture, malignant
transformation, compression of adjacent neurovascular structures,
bursal formation and/or bursitis, or palpable mass.
• Patients with HME are generally more severely affected and present at
a younger age with multiple osseous deformities such as bowing of the
extremities, short limbs, short stature, leg length discrepancy, coxa
valgus or genu valgus.

28. Evaluation
• As previously noted, solitary osteochondromas are generally
discovered incidentally on radiographs while patients with HME
present with symptoms leading to radiographic evaluation.
• Osteochondromas involving the long bones (most common location)
generally have a pathognomonic appearance and require no further
imaging evaluation. On radiographs, the lesions localize to the surface
of the bone in the region of the metaphysis, when involving long
bones, with medullary and cortical continuity.
• The lesions may be sessile or pedunculated. When pedunculated, they
point away from the adjacent joint. The characteristic cartilage cap is
not easily assessable on radiographs.

29. • Additional radiographic findings concerning for malignant
transformation would include changes in morphology, periostitis, or
new indistinctness of the cortical margins.
• Lesions of the flat bones (scapula, pelvis, spine) are often
indeterminant on radiographs and require further imaging to
demonstrate the corticomedullary continuity
• If the patient is symptomatic or demonstrates concerning radiographic
features, further evaluation with cross-sectional imaging (MRI, CT, or
US) is indicated to assess for potential complications.

30. • MRI is ideal for assessing the cartilage cap, which if thickened, may
indicate malignant transformation. The cartilage cap will demonstrate
intermediate to high signal on T2 and proton density (PD) weighted
images.
• Cartilage caps are generally thicker in skeletally immature patients
(range 1 to 3 cm). In skeletally mature patients, the cartilage cap is
generally only a few millimeters. Cartilage caps greater than 2 cm,
especially in skeletally mature patients are concerning for malignant
transformation and require tissue sampling.

31. • Other roll of MRI to assess other complication eg bursitis, MRI is also
useful to assess displacement and/or impingement on neurovascular
structures.
• Patients with HME commonly demonstrate bowing deformities of the
long bones, short stature, and short extremities. The distribution of the
multiple lesions varies in the literature with some authors reporting
bilateral symmetric distribution while others report unilateral. The
individual lesions are similar to the solitary form with both sessile and
pedunculated lesions present. Malignant transformation is more
common in patients with HME, and therefore, clinical and imaging
surveillance is required

32. Radiograph Humerus
Osteochondroma.

35. Treatment / Management
• Treatment varies from patient to patient. In the solitary form, small
asymptomatic osteochondroma without suspicious imaging features requires
only follow-up.
• if the lesion becomes symptomatic further assessment with cross-sectional
imaging is required.
• Large, symptomatic lesions or lesions with suspicious imaging features such
as growth in a skeletally mature patient, irregular or indistinct margins,
focal areas of radiolucency, osseous erosions or destruction require surgical
resection.
• Not surprisingly, excision of pedunculated lesions is easier than sessile
lesions. Following resection, there is a 2% recurrence rate reported in the
literature.

36. • Surgical intervention is much more common in patients with HME
owing to both increased risk of malignant transformation and more
severe osseous deformities. Surgical intervention may be performed to
correct or improve the associated osseous deformities.
• The mere presence of an osteochondroma is not an indication for
surgery. Reasonable indications include

37. (1) pain from external trauma or irritation of surrounding soft tissues,
(2) growth disturbance leading to angular deformity or limb length
discrepancy,
(3) joint motion compromised by juxtaarticular lesions,
(4) soft tissue (tendon, nerve, or vessel) impingement or tethering,

38. (5) spinal cord compression,
(6) false aneurysm produced by an osteochondroma,
(7) painful bursa formation,
(8) obvious cosmetic deformity, and
(9) a rapid increase in the size of a lesion

40. Multiple osteochondromas (MO) in the
forearm
• The forearm is involved in MO often, and osteochondromas are found
most notably in the distal radius and ulna.
• Deformities of the forearm are reported in approximately 40–80 % of
the patients and can be unilateral or bilateral, whereas one forearm is
usually more severely affected than the other.
• Wrist osteochondromas and the developmental deformity give rise to
complaints of pain and or progressive limitation of forearm rotation
during growth.

41. • The most common forearm deformities are:
• 1. a combination of relative shortening of either (usually the ulna) or
both forearms.
• 2. bowing of either one or both forearm bones
• 3. increased ulnar tilt of the distal radial epiphysis
• 4. ulnar deviation of the hand
• 5. progressive ulnar translocation of the carpus and
• 6. dislocation of the radial head

42. • The Masada classification for forearm deformity from MO has been
used since 1989
• The classification is based on the morphological characteristics of the
deformity on plain radiographs
• Type I The main osteochondroma formation is located in the distal
portion of the ulna. The ulna is shortened, and there is bowing of the
radius. However, the radial head is not dislocated (this is the most
common type in 55–61 % of cases).

43. • Type II In addition to ulnar shortening, the radial head is dislocated
(22–33 % of patients). Bowing of the radius is less pronounced than in
type I, and this could be an effect of the dislocation.
• In subtype IIA, the radial head is dislocated because of an
additional osteochondroma at the proximal metaphysis of the
radius.
• In subtype IIB, whilst there are osteochondromas at the distal
ulna, there are none detectable in this region. Dislocation of the
radial head leads to rotational impairment of pronation in general.

44. • Type III The main osteochondroma formation is in the metaphysis of
the distal radius, and there is relative shortening of the radius

46. Management
• Specific indications for surgery are-
• Pain due to impingement of an osteochondroma,
• restriction of motion,
• functional deficits,
• loss of strength,
• severity of deformity and/or
• dislocation of the radial head are recorded

47. • Patients with Masada type I deformity with mild radial bowing and
mild symptoms will be counselled for conservative treatment and
receive yearly follow-up.
• In patients with large osteochondromas which are painful despite
minimal functional impairment, elective removal of the symptomatic
osteochondroma is recommended as are those which give rise to
gradual erosion and deformity of the adjacent bone and limited
rotation and pain.

48. • Patients with advanced deformity and major functional impairment
will be counselled to wait until the age of 13.
• In patients with Masada type IIA deformity, removal of the proximal
osteochondroma (as they are painful) and, in type IIB, removal of the
ulnar osteochondroma is recommended.
• In patients with type III deformity, we offer to remove the painful
osteochondroma but counsel most patients to wait until growth is
completed Some patients in this group need treatment for their
positive ulnar variance, usually by ulnar shortening osteotomy

49. Intraoperative images of a corrective
osteotomy and ulnar lengthening fixator
application at the right forearm with a
Masada type I deformity
A- clinical image of the right
forearm, after marking of the CORA
the osteotomy site at the radius is
exposed;
B-a closing wedge osteotomy is
performed temporary fixation and a
low profile plate
C-fluoroscopic image showing
correction of the radius and good
positioning of the plate proximal to
the growth plate

50. D-via a direct ulnar approach
4 fixator pins are placed into
the distal ulna, note the use
of different angles both in
rotation and abduction of the
pins in order to correct the
deformity of the ulna by pin
placement
E- the monolateral
lengthening fixator is
mounted, both radius and
ulna are straightened;
F- fluoroscopy shows the
radius osteotomy and a nice
alignment of the ulna (

53. Costal exostosis with fungation: A rare
presentation
• Costal exostosis may originate in the region of the costochondral
junction or near the vertebral end. Rib exostosis may cause
considerable chest wall deformity with spreading of ribs. In addition,
it also causes intrathoracic and extrathoracic soft tissue masses.
Costal exostosis is an unusual condition; usually asymptomatic, but
intrathoracic complications have been reported.

54. CASE REPORT
• A 15-year-old boy presenting with right-side chest pain owing to an
ulcerated mass He was also complaining of pain attributed to multiple
bony swellings over the gluteal region, right shoulder, around the
knee on the right side, right ankle, left ankle, around the knee on the
left side, and left humerus, He had no history of recent trauma.
• He had previously received a diagnosis of multiple exostoses.
• Chest computed tomography (CT) revealed an exostosis from the
outer aspect of anterior right fifth ribs with spurs pointing directly
outward to the thoracic cavity
• An ulcerated exophytic mass was present in the chest region

57. DISCUSSION
• Although rare in hereditary multiple exostoses, costal exostoses are
notorious for causing serious complications Movement of the chest
wall (lateral movements due to cardiac pulsations and longitudinal
movements by the diaphragm during respiration) and long
continuous friction between the costal exostosis and viscera are the
two etiological mechanisms that result in injury to the pleura,
diaphragm, and pericardium, causing hemothorax, pneumothorax,
and hemopneumothorax.
• A chest CT scan is more definitive in establishing the diagnosis and
confirming the associated intrathoracic abnormalities.

59. Differential Diagnosis
• The differential diagnosis for osteochondroma includes both benign and
malignant lesions
1.Subungual Exostosis (also referred to as Dupuytren exostosis):
• This is a common lesion of unknown etiology, thought to arise secondary to
prior trauma or infection. The lesions classically arise from the dorsal aspect
of the distal phalanx near the nail bed.
• The lesions may be painful with associated skin ulceration. Like
osteochondromas, subungual exostosis is a surface lesion. However, there is
no medullary continuity. Location is also a key distinguishing feature.

62. • Dysplasia Epiphysealis Hemimelica (Trevor Disease): - This is a
rare process with the development of multiple osteochondromas from
the epiphysis, most commonly of the lower extremities.
• The process is similar to HME, presenting in young patients secondary
to altered gait, osseous deformity or palpable mass. There are no
reports of malignant degeneration in the literature.
• There is a 3 to 1 male to female predominance.

64. • Turret Exostosis: - Extracortical mass on the back of the middle or
proximal phalanx. No medullary continuity.

65. • Bizarre Parosteal Osteochondromatous Proliferation (Nora
lesion):- Surface lesion most commonly involving the osseous
structures of the hands and feet.
• Unknown etiology, however, thought to be secondary to prior trauma.
The lesion does not have medullary continuity. There is no reported
risk of malignant degeneration.

67. • Parosteal osteosarcoma:- Subtype of osteosarcoma arising from the
surface of long bones.
• Radiographs demonstrate a large, lobulated, dense osseous mass
without medullary continuity; however, in advance stages, the lesion
can infiltrate into the medullary space.
• Most commonly arises from the metaphysis of the long bones with the
posterior margin of the distal femur the single most common location.

68. Complications
• Complications of osteochondroma can range from simple cosmetic
concern to serious neurological complications and malignant
transformation.
• Complications fall under three categories,
1. cosmetic deformity,
2. mechanical effect, and
3. malignant transformation.

69. • Cosmetic deformity:- Painless swelling is the most common
complaint that triggers patients to seek medical advice due.
• The osseous deformity is often more severe in HME than solitary
osteochondroma.

70. • Mechanical effect: An osteochondroma can result in various
complications either due to impingement and compression to adjacent
neurovascular structures causing neuropathy and vascular
insufficiency or due to irritation to adjacent soft tissue leading to the
formation of a bursa that could be inflamed and causes pain.
• Neurological impingement by osteochondroma can have a wide
variety of clinical presentations ranging from peripheral neurological
symptoms and radiculopathy due to nerve root compression to more
serious myelopathy and spinal stenosis depending on the site of the
lesion.

71. • The presence of osteochondroma can compromise the blood supply to
the tissues either by the formation of pseudoaneurysm or by direct
compression of the adjacent blood vessels interfering with blood flow.
• Not surprisingly since the knee is the most common location of
osteochondroma, popliteal pseudoaneurysm and peroneal nerve
entrapment are the most common neurovascular complications
• Restriction of joint motion, premature osteoarthritis, and osseous
deformities affecting ADLs are other possible mechanical
complications.

72. • Malignant transformation:
• Malignant transformation is estimated to be 1% in solitary lesions and
up to 3 to 5% in HME.
• An increase in size or change of radiographic appearance as previously
described should raise the suspicion of malignancy.
• Suspicious signs of malignancy on radiograph include surface
irregularity, areas of lucency and heterogeneous mineralization, and
thick cartilage cap (greater than 2 cm). Chondrosarcoma is the most
common form of malignant transformation. However, osteosarcoma
has also been reported.

73. Prognosis
• Osteochondromas are benign lesions and do not affect life expectancy.
The risk of malignant transformation is 1–5%. The prognosis for
secondary peripheral chondrosarcoma is depending on histological
grade.

74. Refrence
• CAMPBELL’S OPERATIVE ORTHOPAEDICS THIRTEENTH EDITION.
• Tachdjian’s Pediatric Orthopaedics From the Texas Scottish Rite
Hospital for Children
• Turek's Orthopaedics: Principles and Their Application, 6th Edition

75. •Thanks you