This document discusses several types of benign bone tumors. It provides information on symptoms, radiographic findings, differential diagnosis, and treatment for each tumor type, including osteoid osteoma, osteoblastoma, osteochondroma, enchondroma, periosteal chondroma, chondroblastoma, chondromyxoid fibroma, fibrous dysplasia, ossifying fibroma, and nonossifying fibroma. For each tumor, it summarizes key clinical details in 1-3 sentences.
4. Plain radiographs
▶ Best initial modality
▶ Should include views in 2 planes
▶ 80 –90 %of cases can be diagnosed
▶ Advanced imaging should not be necessary for clearly benign
lesions
5. Plain radiographs
▶ Where is the tumor? (Long bone or flat bone?; epiphysis,
metaphysis, or diaphysis?; medulla, cortex, or surface?)
▶ What is the tumor doing to the bone? Isthe tumor destroying or
replacing existing bone? If so, what isthe pattern?
▶ What isthe bone doing to the tumor? Isthere periosteal or
endosteal reaction? Ifso, isit well-developed? Isit sharply defined?
What is the type of periosteal reaction: reinforcing, spiculated, solid,
interrupted?
▶ Are there intrinsic characteristics that suggest histology? Isthere
bone formation? Calcification? Isthe lesion completely
radiolucent?
6. Benign lesions
▶ Well-defined or sclerotic border
▶ Sharp zone of transition
▶ Small size or multiple lesions
▶ Confinement by natural barriers (eg, growth plate, cortex)
▶ Lack of destruction of the cortex
▶ Lack of extension into the soft tissue
7. Aggressive lesions
▶ Poor definition
▶ Cortical destruction ("moth-eaten" or permeative pattern)
▶ Spiculated or interrupted periosteal reaction
▶ Extension into the soft tissue
▶ Large size
▶ The absence of these findings does not exclude an aggressive lesion
11. ▶ Presents during the second decade
▶ Proximal femur isthe most common site
▶ Progressively increasing pain that is worse at night and unrelated to
activity
▶ Pain is relieved by aspirin or other nsaids, usually within 20 to 25
minutes
12. ▶ Children with lower-extremity lesions
▶Limp, swelling, muscular atrophy, leg-length discrepancy, bone
deformities, muscle contractures, and local point tenderness
▶ Children with spine lesions
▶ Limp, scoliosis, localized tenderness, restriction of motion, and/or spasm
of paravertebral muscles
13. ▶ 25 percent of osteoid osteomas are not obvious on plain
radiographs
▶ Small, round lucency (nidus) with a sclerotic margin
▶ Central ossification
Radiography
14.
15. ▶ Stress fracture
▶ The pain of stress fractures usually worsens with activity and is relieved
with rest
▶Plain radiographs, stress fractures typically are linear and run
perpendicular or at an angle to the cortex, rather than parallel to it
▶ Bone infections
▶ May have a tract that extends from the lesion toward the nearest
growth plate
▶ Osteoblastoma
▶ The pain is more generalized and chronic and less responsive to nsaids.
▶ It typically has a larger nidus, although this may not be visible
Differential diagnosis
16. ▶ Asymptomatic
▶ Observed with serial examinations and radiographs every four to six
months
▶ Symptomatic
▶ Radiofrequency ablation
▶ Surgical resection
Treatment
18. ▶ Rare benign bone-forming tumor of unknown etiology
▶ Presents during the second decade
▶ Common location isthe posterior column of the spine
▶ Tumors in the spine may be difficult to identify on plain radiographs
19.
20. ▶ Patients with osteoblastoma typically complain of chronic pain less
responsive to nsaids
▶ Children with spine lesions
▶ Limp or neurologic symptoms
▶ Children with lower extremity lesions
▶ Limp
21. Radiography
▶ The radiographic findings are variable
▶ Advanced imaging (eg, CT or MRI) often is required for identification
▶ Appear similar to osteoid osteoma but is usually larger (>2cm in
diameter)
▶ May appear as an expansive lesion, similar to an aneurysmal bone
cyst
▶ Rarely extend into the soft tissues
22.
23. Differential diagnosis
▶ Stress fracture
▶ Infection (eg, osteomyelitis, bone abscess)
▶ Osteoid osteoma
▶ Osteosarcoma, a malignant bone tumor
▶ Aneurysmal bone cyst
27. ▶ Present during the second decade
▶ Around the knee or the proximal humerus
▶ Distal femur isthe most common location
▶ Osteochondroma
▶ Bony spur arising on the external surface of a bone covered by
cartilaginous cap
28.
29. ▶ Hereditary multiple osteochondromas (HMO)
▶ Two or more exostoses in the appendicular and axial skeleton
▶ Autosomal dominant inheritance of a germline mutation in the tumor
suppressor genes EXT1 or EXT2
▶ Prevalence in the general population is approximately 1:50,000
▶ Painless mass near a joint or on the axial skeleton
▶ Painful mass associated with local trauma
30. ▶ Osteochondromas near the ends of long bones are palpable
▶ Osteochondroma can affect nearby growth plates
▶ Can involve the vertebra and may encroach on the spinal canal
▶ HMO may have short stature and angular deformities
▶ Osteochondromas grow throughout childhood
▶ They stop growing when the physes (growth plates) close and
remain static throughout adulthood
31. Radiography
▶ Bony spur (sometimes large) that arises from the surface of the
cortex and usually points away from the joint
▶ The cortex of the spur is continuous with the cortex of the underlying
bone
▶ The cartilage cap is thick in the child (may be >2cm), narrows
during adolescence, and generally is<1cm in the adult
▶ Biopsy and removal of the entire osteochondroma may be
warranted for lesions with a cap ≥2cm thick
33. Treatment
▶ Can be observed without treatment
▶ Indications for excision
▶ Local irritation
▶ Deformity and concern for malignant transformation
▶ Prognosis
▶ Moderate risk of recurrence if osteochondromas are removed before
the physes close
▶ Small lifetime risk of malignant transformation to chondrosarcoma
▶ Osteochondromas of the spine, scapula, pelvis, and proximal femur are
particularly prone to malignant transformation
35. ▶ Benign cartilage-forming tumors that develop in the medulla
(marrow cavity) of long bones
▶ Enchondromas typically present during the second decade
▶ Enchondromatosis (ollier disease) is defined by multiple
enchondromas, often with a unilateral predominance
▶ Enchondromatosis usually presents in children younger than 10 years
▶ Maffucci syndrome is a subtype of enchondromatosis that is
characterized by multiple enchondromas and soft tissue
hemangiomas
36.
37. ▶ The signs and symptoms vary depending upon the anatomic site,
extent, and distribution of involvement
▶ Asymptomatic unless a fracture is present
▶ Ncidental findings
▶ Symptomatic
▶ Widening of the bone, angular deformity, and limb-length discrepancy
38. Radiographic findings
▶ Oval, well-circumscribed, central lucent lesion, with or without matrix
calcifications
▶ Expansion of the surrounding cortex, especially when the lesion is in
the hand or foot
▶ Multiple lesions may be present
39. Differential diagnosis
▶ Bony infarcts
▶ Calcification is mainly in the periphery of the lesion and has a wavy or
serpentine appearance
▶ Low-grade chondrosarcoma
▶ Pain without fracture
40. Treatment
▶ Observation
▶ Asymptomatic
▶ Without increased risk of pathological fracture
▶ Curettage and bone grafting
▶ Fractures should be permitted to heal before curettage
41. Prognosis
▶ Solitary enchondromas usually are self-limited
▶ Recurrence after curettage and bone graft is rare
▶ Malignant transformation of a solitary enchondroma is extremely rare
(<1percent)
▶The riskof malignant transformation isincreased (as high as 20 to 50
percent) in patients with enchondromatosis (Ollier disease) or Maffucci
syndrome
43. ▶ Rare, benign, cartilage-forming tumors that arise from the surface of
the cortex, deep in the periosteum, and erode into the cortex
▶ Occurs in children and adults
▶ Most common site isthe proximal humerus
▶ Pain at the site of the lesion
▶ Palpable nontender hard mass that isfixed to bone
44. Radiographic features
▶ Small, scalloped, radiolucent lesions on the outer surface of the
cortex in the metaphysis or diaphysis
▶ Rim of sclerotic bone
▶ Calcification is present in approximately one-third of cases
▶ Periosteal reaction isminimal
45.
46. Differential diagnosis
▶ Nonossifying fibroma
▶ Soft-tissue tumors, secondarily eroding into the cortical bone
▶ Chondrosarcoma, a malignant tumor
▶ Osteosarcoma, a malignant tumor
49. ▶ Arises in the epiphyses or apophysesof long bones
▶ Presents during the teenage years
▶ The most common sites are the epiphysis of the proximal humerus,
distal femur, and proximal tibia
▶ Low-grade joint pain (constant, unrelated to activity) and swelling
50. Radiographic findings
▶ Small, well-defined lesions with a sclerotic border that may cross the
physis
▶ Matrix calcification may be seen
51.
52. Differential diagnosis
▶ Giant cell tumor
▶ Benign but locally aggressive skeletal tumor that occurs near the growth
plate in young adults
▶ Chondromyxoid fibroma
▶ Avascular necrosis
▶Abnormality of subchondral bone in which pain isactivity related. In
contrast, in chondroblastoma, subchondral bone is normal, and pain is
constant, unrelated to activity
▶ Aneurysmal bone cyst
▶ Osteomyelitis
▶ Clear cell chondrosarcoma
56. ▶ Rare, benign, cartilage-forming tumor of the tubular long bones
▶ Usually presents in the teens or 20s
▶ One-quarterof cases occur in the proximal tibia
▶ Pain and swelling
63. ▶ Lesion in which portions of the bone are replaced by fibrous
connective tissue and poorly formed trabecular bone
▶ Originates in the medullary cavity
▶ Postzygotic mutation in the guanine nucleotide stimulatory protein
(GNAS1) gene
▶ May occur in single or multiple bones
▶ The polyostotic form of fibrous dysplasia isknown as mccune-
albright syndrome and is associated with endocrine abnormalities
and café-au-lait spots
▶ Mazabraud syndrome is characterized by fibrous dysplasia and soft
tissue myxomas
64.
65. ▶ Presents in the teens or 20s
▶ Most common in the proximal femur tibia, ribs, and skull
▶ Most patients with fibrous dysplasia are asymptomatic
▶ May be painful or cause swelling
▶ Repeated pathologic fractures or severe bone deformity
▶ "Shepherd's crook" varus deformity of the proximal femur
66.
67. Radiographic findings
▶ Lytic lesion in the metaphysis or diaphysis with a "ground glass"
appearance
▶ Expansion of the bone and possible bowing
▶ Cortical bone is thinned with a scalloped, undulating pattern due to
endosteal erosion
▶ Periosteal reaction usually is absent unless there is a pathologic
fracture
70. Treatment
▶ Asymptomatic
▶ Observation
▶ Symptomatic
▶ Curettage, bone grafting
▶ Autograft should not be used because it will be resorbed
▶ Bisphosphonate therapy
71. Prognosis
▶ Deformity may progress with skeletal growth
▶ Usually is static after growth ceases but may be reactivated with
pregnancy
▶ Often recurs after curettage and bone grafting
73. ▶ Deformity-inducing fibro-osseous lesion of the tibia and/or fibula
▶ Originates in the cortex
▶ Occurs in children younger than 10 years of age
▶ Swelling and/or anterolateral bowing of the lower leg
▶ Painful only if it associated with a pathologic fracture
74. Radiographic findings
▶ Lytic thinning of the diaphyseal cortical bone with interspersed
sclerosis, causing anterior or anterolateral bowing
▶ Sharply circumscribed margin
75. Differential diagnosis
▶ Monostotic fibrous dysplasia (which originates in the medulla rather
than the cortex)
▶ Adamantinoma (a low-grade malignant bone tumor)
▶ Nonossifying fibroma.
79. ▶ Developmental defect filled with fibrous connective tissue
▶ Known as metaphyseal cortical defect, fibrous cortical defect, and
benign metaphyseal bone scar
▶ Incidental radiographic finding in teenagers
▶ Most commonly in the distal femur, followed by the distal tibia, and
the proximal tibia
▶ Large lesions may be associated with pathologic fracture
80. Radiographic findings
▶ Small, well-defined, eccentric, expansile, lytic lesions located in the
metaphysis with scalloped sclerotic borders
83. Treatment
▶ Asymptomatic
▶ Nonossifying fibromas that are discovered incidentally do not require
any further follow-up
▶ Symptomatic
▶ Curettage and bone grafting
86. ▶ Fluid-filled lesions with a fibrous lining
▶ Generally occur in the first 20 years of life
▶ Proximal humerus and femur are the most common locations
▶ Commonly present with a pathologic fracture
▶ May be an incidental radiographic finding
▶ Localized pain, limp, or failure to use the extremity normally
87. Radiographic findings
▶ Well-marginated cystic lesions of the metaphysis or metadiaphysis
without reactive sclerosis
▶ Usually involves the full diameter of bone, with expansion of the
cortex
▶ "Fallen fragment" or "fallen leaf" sign
90. Treatment
▶ Observation with serial radiographs
▶ Activity restrictions to avoid pathologic fracture
▶ Aspiration and injection with methylprednisolone
▶ Curettage and bone grafting rarely are required for large lesions
that compromise the structural integrity of the bone
93. ▶ Expansile vascular lesions that consist of blood-filled channels
▶ May grow rapidly and destroy bone
▶ Generally are solitary
▶ Primary or related to other benign bone lesions (eg, giant cell tumor,
osteoblastoma, chondroblastoma)
▶ Generally occur in adolescents
94. ▶ May be found in any bone
▶ Most common in the posterior spinal elements, femur, and tibia
▶ Typically cause localized pain
▶ Present with pathologic fracture, limp, or swelling, neurologic
symptoms
▶ Lesions that cross the growth plate may cause growth arrest
95. Radiographic findings
▶ Aggressive, expansile, lytic metaphyseal lesions with an "eggshell"
sclerotic rim
▶ Pathologic fracture or periosteal reaction may be present
▶ Sharply circumscribed
▶ "Soap bubble" appearance secondary to the reinforcement of the
remaining trabeculae that support the bone structure
▶ The cortex isusually intact
96.
97. Differential diagnosis
▶ Unicameral bone cyst
▶ Giant cell tumor, a benign but locally aggressive skeletal tumor that
occurs in young adults
▶ Osteosarcoma, a malignant bone tumor
▶ Osteoblastoma (in the spine).
▶ Chondroblastoma (if they cross the growth plate)
101. ▶ Eosinophilic granuloma of bone
▶ Relatively rare disorder of unknown etiology
▶ Probably arising from circulating myeloid dendritic cells
▶ Most common in children 5 to 10 years of age
▶ Hand-schüller-christian disease classically refers to the clinical triad
of skull lesions, exophthalmos, and diabetes insipidus
▶ Presentation of EGB with a single bone lesion ismore common than
multiple bone lesions
102. ▶ Bones most commonly affected in children include the skull, ribs,
pelvis, long bones, mandible, and vertebrae.
▶ Patients with egb present with painful swelling at the affected bony
site with or without decreased range of motion.
▶ Pathologic fracture or spinal cord compression may also occur.
▶ Biopsy of suspicious lesions and staining for cd1a and/or anti-
langerin (cd207) is needed in order to confirm the diagnosis of egb
▶ Electron microscopy to identify birbeck granules is performed less
frequently
103. Radiographic findings
▶ Well-defined, lytic lesion, with or without sclerotic margins, in the
diaphysis or metaphysis
▶ Periosteal reaction may be absent, benign, or aggressive-appearing
▶ Associated soft tissue mass may be present
▶ Marked flattening of the vertebral body, or vertebra plana, is a
common manifestation
104.
105. Treatment
▶ Asymptomatic
▶ Conservative treatment
▶ Symptomatic
▶ Steroid injection
▶ Curettage and bone grafting
▶ Vertebra plana
▶ Conservative
▶ Temporary bracing
▶ Radiation
▶ Surgical decompression and fusion with instrumentation
108. ▶ 5%of bone neoplasms
▶ Typically occur in patients 20 to 40 years old
▶ Most common location for this tumor isthe distal femur, followed
closely by the proximal tibia and distal radius
▶ Spinal involvement, other than the sacrum, is rare
▶ Usually solitary lesions
▶ Although these tumors typically are benign, pulmonary metastases
occur in approximately 3%of patients
109. ▶ The overall mortality rate from disease for patients with pulmonary
metastases is approximately 15%
▶ Progressive pain that often is related to activity initially and only later
becomes evident at rest
▶ In 10%to 30%of patients, pathological fractures are evident at initial
examination
110. Radiographic findings
▶ Eccentrically located in the epiphyses of long bones and usually
abut the subchondral bone
▶ The lesions are purely lytic
▶ Zone of transition can be poorly defined on plain radiographs
▶ Partial rim of reactive bone may be present
▶ Frequently expands or breaks through the cortex
▶ Intraarticularextension israre
▶ On MRI, the lesion usually is dark on t1-weighted images and bright
on t2-weighted images
111. CLASSIFICATION
▶ Grade I
▶ Intraosseous lesions with well-marginated borders and an intact cortex
▶ Grade II
▶ More extensive intraosseous lesions having a thin cortex without loss of
cortical continuity
▶ Grade III
▶ Extraosseous lesions that break through the cortex and extend into soft tissue