Benign bone lesions




To Bone

Bone response



Soft Tissue







Osteoid Osteoma

?Long bones & post elements

Nidus < 1cm, if > 2cm = osteoblastoma

(subperiosteal = ±scalloping)

Cortical/medullary = intense sclerosis

± calcified central nidus



10 to 35

Benign active

Osteoid with fibrovascular tissue between trabeculae

Stress #, Brodie’s abscess, osteoblastoma, bone island (cold bone scan)

Pain relieved by NSAIDs, scoliosis, hot bone scan

None, NSAIDs, curettage, ablation, en bloc


?post elements, met/dia of long bones, skull

> 2 cm, progressive

Usually lytic, also sclerotic, resemble ABC if lytic

Geographic, sclerotic rim, ±neocorticalization

Poorly visible osteoblastic, bone if small

Aggressive can erode

Neocorticalization if present

10 to 35

Benign aggressive

Trabeculae in fibrovascular stroma, may coexist with GCT or ABC

OO, ABC (esp. spine), GCT, Brodie’s, osteosarc, chondrosarc, chondroblastoma (epiphyseal)

Hot bone scan, difficult to differentiate from osteosarc

En bloc or curettage/bone graft/cement, (RR = 10 – 20%)


Bone surface, calvarium


Focal, dense, homogenous bone, geographic



Smooth, merge


Dx in 5th dec

Benign hamartomatous

Heavily ossified tissue

Parosteal osteosarc, osteochondroma, periostitis, met

Assoc. with Gardner’s synd (auto dom, intestinal polyposis, ST fibromas, sebaceous cysts) ? fibrosarc, ampulla of Vater carcinoma, thyroid Ca

Excise if symptomatic

Osteochondroma (“exostosis”)

Metaphyseal, knee, shoulder, hip


Metaphysis may be expanded and remodeled


Enchondral ossification of cartilage cap, cartilaginous matrix prior to maturity

Contiguous marrow cavity, grows away from epiphysis

Non-ossified cartilage cap >1 or 2 cm in an adult suggests malignant transformation (chondrosarcoma)

10 to 35

Benign latent, parosteal or surface lesion

Cartilage cap matures into trabecular bone

Juxtacortical myositis ossificans, periosteal chondroma, surface or soft tissue osteosarcoma

Assoc. with familial osteochondromatosis, MRI shows thickness of cartilage cap, CT shows contiguous marrow, malignant transformation risk 1% for solitary, higher more proximal

Asymptomatic = no treatment, excise if painful or NV compression, recurrence rate if immature


Metadiaphysis, femur, humerus, diaphyseal in hand (prox phal > MC > mid phal > dist phal

3 to 5 cm, smaller in hands and feet

Minor endosteal erosion, hand lesions may be quite aggressive but are still benign

Geographic, little endosteal response

Popcorn calcification in long bones, radiolucent in hand and foot

Cortical erosion usually only in hand and foot

None, rarely enchondroma protuberans in hand

15 to 40

Benign latent, except pathologic # in phalanges

Well-circumscribed lobules of cartilage

Medullary bone infarct, GCT in metacarpals, fibrous dysplasia, UBC, chondrosarcoma

Assoc. with Ollier’s and Maffucci’s, worrisome = endosteal scalloping, permeative lucency, rare malignant transformation

Biopsy if change with time, persistent pain, worrisome Xray features. Xray @ 3, 6 12 months. Curettage & BG

Chondromyxoid fibroma

Proximal tibia, distal femur, metaphyseal, eccentric

3 to 10 cm


Geographic, sharp sclerotic margin

Not usually seen

Cortical erosion or ballooning


10 to 30

Benign aggressive cartilage lesion

Firm, tan tissue with lobular pattern, myxoid or chondroid matrix

GCT, ABC, UBC, nonossifying fibroma, chondroblastoma, infection, osteoblastoma, Brown tumour, telangiectatic/chondroblastic osteosarcoma


Biopsy, curettage & BG or marginal excision, recurrence < 20%


Epiphyseal/apophyseal, femur > humerus > tibia > pelvis > tarsal bones


Lytic lesion with geographic margin

Sclerotic rim of reactive bone

Lytic, possible internal cartilaginous calcifications

Expansion if metaphyseal


5 to 25

Benign aggressive giant cell and chondroid type lesion

Proliferating chondroblasts, chondroid matrix (pink not blue), numerous giant cells

Degenerative joint cyst, enchondroma, clear cell chondrosarcoma, GCT

GCT is usually epiphyseal-metaphyseal and has no calcifications, no ossifications, and no sclerotic margin

Thorough curettage & BG, recurrence 10 to 30%

Periosteal chondroma

Eccentric, subperiosteal, external to cortex, metaphyseal cortex of long bones, esp. prox humerus, tibia, femur, and small tubular bones of hands and feet


Periosteal, causes cortical erosion

Well defined, shallow, geographic, peripheral periosteal elevation and reaction

Radiolucent, scattered calcifications

Cortical erosion


2nd to 4th decades

Benign active, slow growing, rare

Hyaline cartilage, nodules on surface of the cortex

Periosteal chondrosarcoma or osteosarcoma, adjacent soft tissue neoplasm


En bloc resection, narrow margin

Synovial chondromatosis

Periarticular, intra-articular loose bodies, knee >> hip, shoulder, elbow, ankle

Multiple calcified bodies, mm to cms

Degenerative arthritis

Mild reactive sclerosis from bone erosion

Cartilage +/- calcification/ossification


Extension into bursae around distended joints

3rd to 5th decades

Benign cartilaginous lesion

Nodules of chondroid tissue both free and within synovium

Loose bodies: secondary osteochondromatosis, osteochondral #, OA, Charcot, osteochondritis dessicans


Remove loose bodies, total synovectomy

Fibrous cortical defect

Distal femur and tibia, eccentric, cortical, metaphyseal

< 4cm

Radiolucent, elliptical

Sharp demarcation, thin sclerotic margin


Entirely a cortical lesion


Age 4 to 8

Benign latent

Cortex replaced with fibrous tissue, spindle cell proliferation, storiform pattern, giant cells, ++iron (Prussian blue)

Infection, chondromyxoid fibroma, fibrous histiocytoma, nonossifying fibroma

Symptomatic almost exclusively in children, spontaneously resolves with cessation of growth

Observation, 3,6,12 months if lesion atypical

Nonossifying fibroma

Tibia and femur, expands into medullary cavity

> 4cm

Fracture risk as enlargens

Thin, sclerotic, lobulated margin


Expanded and thinned



Benign latent or active

Identical to fibrous cortical defect

ABC, fibrous dysplasia, chondromyxoid fibroma

Arises from a fibrous cortical defect that enlarges into metaphysic, most lesions spontaneously heal

Curettage & BG +/- ORIF if: atypical location, questionable diagnosis, intractable pain, impending path #

Fibrous dysplasia – monostotic

Ribs > femur > tibia > maxilla > mandible > skull > humerus, usually spares epiphysis but can be throughout bone

Variable, can involve entire bone

Lytic to ground glass, endosteal expansion

Well-demarcated sclerotic border, limited periosteal response

Osseous matrix if present can produce ground glass appearance

Endosteal erosion


Late childhood into adulthood

Benign latent, active, or aggressive

Cellular fibrous tissue with immature woven bone “Chinese character” shapes

UBC, nonossifying fibroma, solitary EG, ABC, GCT, hemangioma, infection, central low-grade osteosarcoma, fibrosarcoma, Ewing’s

Fibrous dysplasia is the third most common cause of secondary osteosarcoma arising in diseased bone after Paget’s and radiation

Biopsy may be required for diagnosis, bracing, activity modification

Fibrous dysplasia – polyostotic

Femur > craniofacial bones > tibia > humerus > ribs > fibula

May progress in size and number until skeletal maturity

Geographic, more aggressive than monostotic

Endosteal expansion

Same as monostotic

Fusiform expansion of cortex


Younger than monostotic, esp. if endocrine disorder


Same as monostotic

Multiple enchondromatosis, Paget’s, Brown tumour, metastasis, von Recklinghausen’s (NF, café au lait), MM, EG

Earlier onset = more progressive, 25% polyostotic, assoc. with McCune-Albright syndrome

Bone scan useful for detecting multiple lesions, can usually be diagnoses on Xray

Ossifying fibroma = Osteofibrous dysplasia = Kempson-Campanacci

Usually proximal anterior tibia, eccentric, diaphyseal



Blister-like areas of cortical lucency surrounded by dense sclerosis, geographic


Intact and expanded



Benign active or aggressive

Woven bone trabeculae in fibrous stroma

Adamantinoma (age), fibrous dysplasia, nonossifying fibroma, osteoblastoma, ABC

Very rare, can progress to adamantinoma

Observe if asymptomatic, high recurrence if <10, excision & BG

Giant cell tumor

75% in epi/metaphysic of long bones, 50% around knee, distal radius, prox humerus, vertebrae, sacrum

Usually >50% bone diameter

Lytic, geographic, often extends to subchondral bone

Expansile, usually non-sclerotic


Neocorticalization if perforates cortex

Almost always occurs by eroding through cortex (as opposed to Ewing’s), 20%

80% > 20 years old, <5% with open plates

Benign aggressive, rarely metastatic (5%)

Multinucleated giant cells, hemosiderin = low signal on both T1 and T2

ABC, Brown tumour (Serum Ca), telangiectatic osteosarcoma, fibrosarcoma, osteoblastoma

Campanacci stages:
1. early, bone has normal contour
2. active, erosion, expansion
3. destructive, poor margin, cortical break +/- path #

Expendable bone = wide en bloc, non-expendable = curettage, adjuvant phenol/Nitrogen, BG or cement, 10-25% recur

Aneurysmal Bone Cyst

Spine (esp. post), femur, tibia, metaphysic of long bones, usually eccentric, can be diaphyseal

Variable, usually > 5cm

Lytic and expansile

Marginal sclerotic rim, neocorticalization



Generally contained lesion

<30, 80% <20

Benign aggressive, not metastaic

Hemorrhagic cystic tissue, lacks endothelial cell lining, walls are fibrous tissue and giant cells

UBC (generally central), GCT (may co-exist), osteoblastoma, telangiectatic osteosarcoma

ABC and osteoblastoma both appear in posterior spine, MRI = multicystic, fluid-fluid level, markedly expansile

Open biopsy, curettage & BG/cement, recurrence 10-20%, en bloc in expendable bone

Unicameral bone cyst

Central medullary lesion, thought to begin in metaphysic and migrate to diaphysis, 80% = prox humerus or prox femur, also ilium, calcaneus, talus

Can be quite large

Lytic, lobulated borders

Geographic, thin sclerotic margin


Often circumferential endosteal erosion


80-90% < 20, younger = more active

Benign latent or active lesion of bone

green-yellow fluid, wall is fibrous tissue

ABC, fibrous dysplasia, chondromyxoid fibroma, telangiectatic osteosarcoma, infection, nonossifying fibroma

Fallen leaf sign = cortical fragment falls into lesion in path #, MRI = fluid-fluid only if path #, minimal bony expansion

Plain films and aspiration usually diagnostic, open biopsy if no fluid or hemorrhagic

Eosinophilic Granuloma

Diaphyseal or metaphyseal, skull, ribs, vertebrae, pelvis, and long bones (mostly femur and humerus), almost never hands or feet


Lytic, can be patchy, long bone expansion less common, path # common in spine (vertebra plana)

Commonly geographic, minimal metaphyseal sclerosis, may be periosteal reaction or onion skinning

None, except hazy matrix at resolution stage

Thinned, scalloped, onion skinning


5 to 10, rare after 30

Benign active or aggressive, can be multiple, tumour-like disorder, belongs to Langerhans’ cell histiocytoses

Friable tan tissue, histiocytes, Langerhans’ cells (S100+, Birbeck granules on EM), eosinophils, giant cells

UBC (usually metaphyseal, larger, less painful), osteomyelitis,
Onion skinning = Ewing’s, non-Hodgkin’s lymphoma, osteomyelitis, osteosarcoma

Often heals spontaneously (months to years),
Biopsy may trigger healing

Indications: 1.diagnosis, 2.persistent pain, 3.prevention or treatment of pathologic fracture.
Diagnosed lesions may be observed

Hemangioma of bone

Spine > craniofacial > femur or humerus > hands and feet


Vertebrae = vertical striations (corduroy), honeycombing

Rarefaction, reactive ossification


“disappearing bone disease”, ballooning


40 to 60

Benign latent or active, often incidental

Hemorrhagic, vessels, dilated capillaries between bone trabeculae

Spine = Paget’s (picture frame appearance, expansion), myeloma, metastasis

Gorham’s disease (massive lysis that can cross joints)

Asymptomatic = no treatment, vertebra collapse treated if neuro deficit, chronic pain, pre-op embolization

Familial Osteochondromatosis

  • Autosomal dominant, variable penetrance
  • 30% spontaneous
  • Short stature, unequal growth of radius and ulna – Madelung deformity (radial deviation of the hand due to ulnar plus), unequal growth tibia and fibula – valgus knees and ankles
  • Long bones, pelvis, ribs, scapula, distal ends of proximal and distal phalanges
  • Monitor for malignant change

Ollier’s disease = multiple enchondromatosis

  • Inborn error of osseous development
  • non-hereditary
  • Often unilateral, metaphysic & diaphysis
  • Deformity, growth disturbance
  • 25-30% risk of transformation to low- or intermediate grade chondrosarcoma

Maffucci’s syndrome

  • Congenital, non-hereditary
  • Multiple enchondromas and multiple soft-tissue hemangiomas
  • Calcified phleboliths
  • Higher risk of malignant transformation than Ollier’s

McCune Albright syndrome

  • Polyostotic fibrous dysplasia – tendency to be unilateral
  • Café au lait spots – midline neck, chest, shoulders, sacrum, rough borders unlike NF
  • Multiple myxomas
  • Endocrine disturbances – Cushing’s, hyperthyroidism, acromegaly, various adenomas
  • Classically present with precocious puberty and short stature

Letterer-Siwe Disease

  • Associated with EG
  • Acute, fulminant disease affecting infants < 2
  • Hepatosplenomegaly, adenopathy, CNS involvement, fever, anemia, thrombocytopenia
  • Potentially fatal
  • Treated with corticosteroids and chemo

Hand-Schuller-Christian disease

  • Develops in <20% of patients with EG
  • Onset usually 5 to 10 years old, rarely sooner
  • Exophthalmos (retro-orbital invasion), diabetes insipidus (sphenoid invasion), skull defects (classic triad < 10% of patients)

Malignant bone lesions






To Bone

Bone response



Soft Tissue








Central Osteosarcoma

Conventional (75%)

Metaphysis, may extend across physis, distal femur, proximal tibia, proximal humerus, flat bones

Large (>5 cm)

Permeative, patchy lytic/sclerotic

Sunburst, Codman’s triangle, no marginating reaction

Osteoid with variable sclerosis


May occur without cortical destruction, poorly organized bony matrix

2 to25;
Secondary osteosarcomas (Paget’s) >50

Methotrexate, adriamycin, cisplatin, ifosphamide

Osteoid in lace-like, or sheet-like pattern, cells spindle, epithelioid, or small and round

GCT, ABC, Ewing’s, osteoblastoma, mets, lymphoma

Alk phos, LDH often elevated, local recurrence is almost always associated with metastases, removal of lung mets often prolongs survival, radiation ineffective

Biopsy with MSK oncologist, neoadjuvant chemotherapy prior to limb salvage, 5-yr survival 50-85%,




Metaphysis femur, tibia, humerus


Lytic, expansile, rarely permeative

+/- periosteal reaction



Usually, with hemorrhage




ABC, GCT, Brown tumour, osteoblastoma


Similar to conventional




Most metaphysis of long bones, less diaphysis


Lytic with internal sclerosis/ trabeculations

Wide zone of transition



Not usually

Young adults, mean 30


Difficult to diff from fibrous dysplasia, minimal atypia

Fibrous dysplasia, fibrosarc, infection, lymphoma

Better prognosis than conventional, rare path #




In Pagetoid Bone








46 to 91


Usually high grade


Also chondrosarc, fibrosarc, MFH

Prognosis worse: large, axial, older (no chemo)



Small Cell

Metaphyseal distal femur, humerus


Sclerotic or mixed, permeative





10 to 30


Sheets of small, round, blue cells



Rare, differs from Ewing’s by making osteoid




2/3 post distal femur, prox medial humerus, lat prox tibia


“Applied” to bone (plasticine), may encircle



Juxtacortical sclerotic mass, lobulated large base



Chemo if high grade

Fibrous, osseous, cartilaginous elements. Often low-grade, well-formed trabeculae

Periosteal osteosarc or chondrosarc, myositis ossificans, exostosis

Highest osteosarcoma prognosis

Biopsy with MSK surgical oncologist, wide resection, chemo if high grade



High-Grade Parosteal (Dedifferentiated)

2/3 post distal femur, prox medial humerus, lat prox tibia











Similar to central




Metaphyseal and diaphyseal femur and tibia


Destructive, periosteal reaction, Codman’s

Periosteal new bone in spiculed pattern

Stippled calcification, denser at base

Scooped out



Chemo if high grade

Generally low grade

High-grade surface osteosarc, periosteal chondrosarc, Myositis oss.


Wide excision




Prox/dist femur, prox humerus, scapula, pelvis

>5 cm, variable

Geographic, destruction proportional to grade

Endosteal expansion

Punctuate calcifications

Endosteal scalloping, maybe cortical thickening

More in high grade


Not effective primary therapy, rads can be used if wide resection not possible

Myxoid or chondroid, binucleate cartilage cells, grade determined by atypia

Enchondroma, osteosarc, fibrosarc, MFH, mets, chordoma if sacrum

More distal location is more likely benign, lung mets can be years after

Biopsy with MSK surgical oncologist, wide resection









May invade canal





Periosteal chondrome, periosteal osteosarc




Clear cell


Epiphysis or metaphysic of long bone, esp. prox femur and humerus


Lytix, geographic

Sharp sclerotic margins


Intact but may be expanded






Rare, low grade, can metastasize

Wide resection






Lytic, destructive, permeative






Sometimes chemo

Small, round, blue cells with chondroid


Rare, high grade, poor prognosis

Wide resection




Similar to central







Similar to central


Mix of chondrosarc with fibrosarc or MFH


Rare, high grade, usually mets by 2 yrs

Wide resection




Pelvis, dist femur, prox tib, prox humerus, central > eccentric

Usually > 5cm


Permeative, no sclerosis


Thinned, destroyed, maybe periosteal rxn

Common in high grade


rads for palliation

Herringbone pattern spindle cells, atypia

MM, solitary met, GCT, MFH, dediff chondrosarc, (Ewing’s if < 25)


Biopsy with MSK surgical oncologist, wide resection




Metaphysic of long bones, 50% in femur

Usually > 5cm

Lytic, destructive

Permeative, but may have sclerotic margin in low grade




Bimodal 50-60, and 20-30

Neoadjuvant and adjuvant chemo

Malignant spindle cells in storiform pattern, mix of giant cells, histiocytes


Unknown cell of origin

Biopsy with MSK surgical oncologist, wide resection, chemo