Benign bone tumors an approach

Dr . Rafeevudh Dharaja

BENIGN BONE TUMORS – AN APPROACH

الرحمن الله بسمالرحيم

 Bone-forming tumors • Osteoid osteoma • Osteoblastoma

Cartilage-forming tumors • Osteochondroma • Chondroma • Chondroblastoma • Chondromyxoid

fibroma

Fibrous lesions • Fibrous dysplasia • Ossifying fibroma • Nonossifying fibroma

Cystic and vascular lesions • Unicameral bone cyst • Aneurysmal bone cyst

CHARACTERISTICS OF 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

APPROACHAge at Presentation• Primary bone tumours are rare below the age of 5

years and over the age of 40 years.

• Osteoid osteoma • Osteobastoma• Enchondroma • Chondroblastoma- teenage• Chonromyxoid fibroma• ABC• FD – before 30 yrs•

• Solitary or multiple?• Which bone affected? e.g.

long bone vs. spine• Where is the lesion in the

bone?• Well-defined margins?• Cortical destruction?• Bony reaction?• Central calcification?• Look also at the soft

tissues.

• Enchondromatosis• FD• Adamantinoma

KEY QUESTIONS TO ASK OURSELVES • Posterior elements of

spine - Osteoblatoma-• Metacarpals and

phalanges - Enchonromatosis -

• Calcaneum - Interosseous lipoma-

• Humerus - Simple bone cyst

• Tibial anterior cortex- adamantinoma

• Epiphysis – chondroblastoma• Metaphysis – CMF, ABC• Diaphsis – LCH, SBC• Medullary cavity –

enchondroma CMF, FD• Surface of cortex - periosteal

chondroma• Cortex- fibrous cortical defect

• Solitary or multiple?• What type of bone, e.g. long bone vs. spine vs.

ribs?• Where is the lesion in the bone?• Well-defined margins?• Cortical destruction?• Bony reaction?• Central calcification?• Look also at the soft tissues.

Lesion margin• In benign and low-grade

malignant neoplasms, this margin is sharp - geographical; Type 1

Type 1A has a rim of sclerosis between the lesion and the host bone Type 1B is a very well defined lytic lesion but with no marginal sclerosis Type 1C has a slightly less sharp, nonsclerotic margin

Type 2 - moth-eaten destruction, characterised by multiple lucent areas measuring 2–5 mm in diameter separated by bone which has yet to be destroyed Moth-eaten- caused by the coalescence of multiple small lytic areas. Type 3 - is permeative destruction, which is the most aggressive pattern - composed of multiple coalescing small ill-defined lesions of 1 mm or less in diameter with a zone of transition of several centimetres

AP radiograph of the ilium reveals the classic moth-hole appearance (arrows) of moth-eaten destruction

AP radiograph of the ilium shows the typical diffuse, ill-defined appearance of permeative destruction. 

• Solitary or multiple?• What type of bone, e.g. long bone vs. spine vs.

ribs?• Where is the lesion in the bone?• Well-defined margins?• Trabeculated?• What type of matrix ?• Cortical destruction?• Bony reaction?• Central calcification?• Look also at the soft tissues.

Matrix Mineralisation

• Chondral calcifications are typically linear, curvilinear, ring-like, punctate or nodular

• Osseous mineralisation is cloudlike and poorly defined

• Diffuse matrix mineralisation in benign fibrous tumours produces the characteristic ‘ground-glass’ appearance

Typical punctate chondral calcification in grade 11 chondrosarcoma

‘cloud-like’ osseous mineralisation in patient with osteoblastic osteosarcoma

Fibrous dysplasia showing typical ‘ground-glass’ mineralisation

• Solitary or multiple?• What type of bone, e.g. long

bone vs. spine vs. ribs?• Where is the lesion in the

bone?• Well-defined margins?• Trabeculated?• Cortical destruction?• Bony reaction?• Central calcification?• Look also at the soft tissues.

• GCT• CMF• ABC• NOF

GCT

• Solitary or multiple?• What type of bone, e.g. long bone vs. spine vs.

ribs?• Where is the lesion in the bone?• Well-defined margins?• Cortical destruction?• Bony reaction?• Central calcification?• Look also at the soft tissues.

Periosteal Reaction• Solid periosteal reaction

- slow rate of growth but not necessarily a benign tumour- OO, chondroblastoma

• Laminated periosteal reaction - subperiosteal extension of tumour, infection or haematoma. Lesions demonstrating periodic growth may show a multi-laminated pattern

• Solitary or multiple?• What type of bone, e.g.

long bone vs. spine vs. ribs?

• Where is the lesion in the bone?

• Well-defined margins?• Cortical destruction?• Bony reaction?• Central calcification/ lytic

nidus• soft tissue reaction?

• Osteoid osteoma• osteoblastoma

• Chondroblastoma

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

In other places

FOR BONE LESIONS

Further imaging essential if malignancy a possibility:• Bone scan will identify other lesions.• CT identifies bony architecture.• MRI gives invaluable soft tissue and bony

information, particularly tumour extent.

Cartilage tumours Osteochondroma Chondroma Enchondroma Periosteal chondromas Multiple chondromatosis Chondroblastoma Chondromyxoid fibroma

CARTILAGE TUMOURS Osteochondroma

Age • Highest incidence is in the second decade.

Location• Long bones are commonly affected, especially

around the knee (~40%)• Commonest locations - distal femur, proximal

humerus, proximal tibia and proximal femur.• The commonest flat bones affected are the ilium

and scapula

• Continuity between the medullary cavity of the lesion and that of the underlying bone is essential for the diagnosis

• Cartilage cap is optimally demonstrated on axial proton density-weighted (PDW) or T2W fast spin-echo (FSE) MRI

• It should not exceed 2-cm thickness in adults

• Outgrowth from the normal cortex, with which it is continuous

• Pedunculated lesions have a long slim neck

• Sessile lesions have a broad base from the bone of origin

Diaphyseal aclasis:• Hereditary multiple

exostoses,HME• Uncommon autosomal

dominant disorder• Exostoses may be

larger than the solitary variety

• The metaphyses in this condition are also typically widened and dysplastic

Complications:• Bursa formation• Neurovascular compromise• Pseudoaneurysm

ENCHONDROMA• Intramedullary neoplasm comprising lobules of

benign hyaline cartilage• Enchondromas affect the tubular bones of the

hands and feet in 40–65% of cases • Proximal phalanges (40–50%),• Followed by the metacarpals (15–30%) and • Middle phalanges (20–30%).

Patients present due to• Increasing size• Pathological fracture• Or incidental finding

RADIOLOGICAL FEATURES• Most enchondromas arise

centrally in the phalanges and metacarpals

• Well-circumscribed, lobular or oval lytic lesions, which may expand the cortex

• Chondral-type mineralisationmay be present

• Enchondroma protuberans- eccentrically placed enchondroma with associated extraosseous component covered by a thin shell of intact cortical bone

Lobular, mildly expansile lesion with typical chondral matrix mineralisation

Eccentrically placed enchondroma of the fourth toe proximal phalanx (arrowhead) with an associatedextraosseous component covered by a thin cortical shell

Large enchondroma or a grade 1 chondrosarcoma??• Lesion size above 5–6 cm

and deep endosteal scalloping are suggestive of chondrosarcoma

Low-grade chondral tumours- MRI features• Lobular margin with

intermediate T1-weighted signal intensity

• T2-weighted-hyperintensity without surrounding reactive oedema

ENCHONDROMATOSIS

Multiple enchondromas, with expansion of the proximal right femur

Maffucci’s Syndrome• Multiple enchondromas and soft-tissue

haemangiomas

CHONDROBLASTOMA• Between the ages of 5 and 25 years (mean age ~20

years).Location• Around knee• Proximal humerus• Proximal femur• Eccentrically in the epiphysis (40%), but with

partial closure of the growth plate it usually extends into the metaphysis (55%)

• Commonest tumour of the patella• Presents as monoarthropathy, since it is typically

located in the epiphysis of a long bone,

Radiological Features• Lobular with a fine

sclerotic margin, measuring 1–4 cm in size

• Matrix mineralisation is demonstrated in ~30%

• Linear metaphyseal periosteal reaction is present in almost 60% of long bone cases

• MRI shows intermediate T1W SI

• Variable SI on T2W images

• Associated marrow and soft-tissue oedema and reactive joint effusion

• Rarely associated with metastases (especially to the lung)

• Rare variant termed ‘aggressive’ (atypical) chondroblastoma, associated with cortical destruction and soft-tissue extension

CHONDROMYXOID FIBROMA• Between 10 and 30 years of age (mean age 25

years).• Long bones -60% of cases, • 40% arising in the flat bones (ilium 10%) or • Small tubular bones of the hands and feet

(17%).

25% of all chondromyxoid fibromas- upper third of the tibia

• Diagnosis – mainly depends on location

• In the proximal tibia eccentric, lobular bubbly lesion with a sclerotic margin

RADIOLOGICAL FEATURESEccentric lytic lesion with a sclerotic margin and expansion of the anterior cortex.

Osteogenic tumours Osteoid osteoma Osteoblastoma

OSTEOGENIC TUMOURS

Osteoid Osteoma (OO)

• Characteristic clinical picture of night pain relieved by aspirin

• Second and third decades of life• Occurs anywhere in appendicular skeleton• Most common in the appendicular skeleton,

with over 50% located in the diaphysis or metaphysis of the tibia or femur

• The characteristic feature of OO is the nidus, which may appear lytic, sclerotic or most commonly of mixed density depending upon the degree of central mineralisation.

• Nidus measures up to 15 mm in diameter and is commonly surrounded by a region of reactive medullary sclerosis and solid periosteal reaction.

• CT demonstrates the classical features of a round or oval soft-tissue density nidus, which commonly shows central dense mineralisation

• Vascular groove sign - thin, serpentine channels in the thickened bone surrounding the nidus

MR- heterogenously low–intermediate SI on both T1W and T2W images enhancing strongly with contrast

Edema-like marrow and soft-tissue SI is almost invariably seen adjacent to the nidus.

• Intra-articular lesions are most commonly seen in the hip

• Present with local osteopenia due to disuse• Soft-tissue oedema-like changes and a joint effusion

• In the ankle and foot -subperiosteal region of the talar neck is a classical site

OSTEOBLASTOMA• Histological similarities to OO and is

differentiated primarily by its size, greater than 1.5 cm in diameter.

• More aggressive growth pattern with potential for extraosseous extension, and does not resolve spontaneously.

• Under the age of 30 years • Common location is the posterior column of the spine • Tumors in the spine may be difficult to identify on plain

radiographs

• Humerus is the commonest location in the appendicular skeleton

• The lesion arises in the medullary cavity

RADIOLOGICAL FEATURES• Predominantly lytic lesions

measuring over 2 cm in diameter

• Larger lesions showing a greater degree of matrix mineralisation

• CT – occult calcification, which can be punctate, nodular or generalised

• Larger lesions may result in bone expansion

• MRI - low–intermediate SI lesion with associated reactive changes as seen with OO, but of a lesser intensity

Large mixed lytic-sclerotic lesion in the medullary cavity with associated periosteal thickening

Fibrogenic tumours Desmoplastic fibroma Fibrohistiocytic tumour Benign fibrous hystiocytoma Fibrous cortical defect Non ossifying fibroma

FIBROGENIC TUMOURS Desmoplastic Fibroma

• Rare, locally aggressive benign neoplasm• Similar histological features to soft-tissue

fibromatosis.• Between 10 and 30 years of age (mean age 21

years)• Usually arises in the metaphyseal region of long

bones (femur, humerus, tibia and radius constitute 56% of cases), the mandible (26%) and ilium (14%)

• Rarely associated with fibrous dysplasia

RADIOLOGICAL FEATURES

• Most lesions are metadiaphyseal and arise as either subperiosteal or intraosseous tumours.

• Many are large at presentation (over 5 cm in diameter)

• Two patterns are seen: an ill-defined moth-eaten or permeative lesion an expanding, trabeculated lesion

Expansile aggressive metaphyseallesion

FIBROHISTIOCYTIC TUMOURS

• Fibrous cortical defect,• Non-ossifying fibroma and• Benign fibrous histiocytoma

Identical histological appearances Different in their clinical and radiological features.

• As an incidental finding, in the distal femoral and proximal tibial metaphyses

• Cortically based lytic lesion commonly with a thin sclerotic margin

• Consolidates/fades with time

FIBROUS CORTICAL DEFECT

• Commonly identified incidentally

• May present with pathological fracture when large enough

• In the second decade of life

• Majority involve the lower limbs, particularly the tibia and distal end of the femur

NON-OSSIFYING FIBROMA

Lobular lesion (arrows) expanding the distal fibular metadiaphysis

Axial PDW FSE and coronal T2W FSE MR images showing a lobular lesion (arrows) containing prominent areas of hypointensity due to its fibrous nature.

Jaffe–Campanacci syndrome• Multiple (usually unilateral) NOFs with café-

au-lait spots

Radiological Features

• Metaphyseal or diametaphyseal and essentially intracortical

• Lobular appearance is classical• Lesion usually enlarging into the

medullary cavity.• Long axis in the line of the bone• When NOF arises in a slim bone such

as the fibula, it crosses the shaft readily and its characteristic intracortical origin is less obvious

• Low–intermediate SI on T1W and PDW images and enhances with contrast

BENIGN FIBROUS HISTIOCYTOMA• Uncommon lesion occurring in an older age

group• Between 20 and 50 years, with a mean age in the

third decade

Radiological Features• Lesion resembles a giant cell tumour• Eccentric subarticular location, but with a well-

defined sclerotic margin indicating slower growth

Giant cell tumour Giant cell tumour

Vascular tumours Haemangioma

Smooth muscle tumours Leiomyoma

Lipogenic tumours Lipoma

Neural tumours Neurilemmoma

GIANT CELL TUMOUR• Aggressive benign neoplasm• Between 18 and 45 years of age• Always occurs in a subarticular or

subcortical region• Adjacent to a fused apophysis of

a long bone - with the knee (distal femur/proximal tibia—55%), distal radius (10%) and proximal humerus (6%) being the commonest sites.

RADIOLOGICAL FEATURES• Subarticular, eccentric, lytic

lesion with a geographic, non-sclerotic margin

• Usually measures 5–7 cm in size.

• Apparent trabeculation and cortical expansion are common features

• Cortical destruction with extraosseous extension may occur in up to 50%

Distal radial subarticular lytic lesion (arrows) with internal trabeculation

Eccentric, subarticular lytic lesion of the proximal tibia with a poorly defined margin (arrows) and destruction of the lateral cortex.

• Iso- or hypointense on T1W Images heterogeneous hyperintensity on STIR

• Areas of hyperintensity on T1W indicate the presence of subacute haemorrhage

• Profound hypointensity on T2W images due to the deposition of haemosiderin from chronic recurrent haemorrhage

Sagittal T1W

Important DDs• Lytic osteosarcoma • In older patients, malignant fibrous histiocytoma or • Subarticular lytic metastasis, particularly from a

primary renal tumour.

VASCULAR TUMOURS Haemangioma

Haemangiomas are classified histologically as • Capillary,• Cavernous, • Arteriovenous or • Venous

• Osseous capillary haemangiomas most commonly affect the vertebral body

• Osseous cavernous haemangiomas affect the skull vault• Involvement of the appendicular skeleton is relatively rare

RADIOLOGICAL FEATURES

• Fine or coarse vertical trabeculation is seen involving the epiphyses and metaphyses of long bones, with the direction of the linear striations running along the axis of the bone

• Bone expansion and extraosseous extension are also recognised features

• Scintigraphy typically shows triple-phase uptake due to the vascular nature of the lesion.

Expansile lytic lesion (arrows) containingcoarse trabeculation.

• CT demonstrates the thickened trabeculae as dense ‘dots’ within a fatty matrix

• MRI - intermediate SI on T1W and hyperintense on T2W

Poorly defined lytic lesion containing multiple, dense thickened trabeculae

• Intraosseous Lipoma• Parosteal Lipoma

Intraosseous Lipoma• Arises in the medulla

and produces expansion,• Predilection for the

calcaneus and femur• CT and MRI demostrates

fatty nature of the matrix

LIPOGENIC TUMOURS

well-defined lytic lesion (arrows) in the calcanealbody

Parosteal Lipoma• Rare lesion- most

frequently encountered around the proximal radius

• May result in pressure erosion of the bone and the formation of circumferential juxtacortical new bone.

Axial CT of the elbow showinga fatty mass (arrows) arising in association with a parostealbony lesion (arrowhead) from the proximal radius

Miscellaneous lesions Aneurysmal bone cyst Bone cyst Fibrous dysplasia Osteofibrous dysplasia Langerhans cell histiocytosis (eosinophilic granuloma) Erdheim–Chester disease Chest wall hamartoma

ANEURYSMAL BONE CYST

• Between 5 and 20 years of age• Long bones (>50% of cases) and spine (20%

of cases) are most common• Involvement of flat bones is most common in

the pelvis.• Secondary ABC change can develop in non-

ossifying fibroma, chondroblastoma, giant cell tumour, fibrous dysplasia, osteoblastoma and osteosarcoma.

RADIOLOGICAL FEATURES

• Classical lesion – purely lytic, expansile intramedullary lesion in the metaphysis of a long bone extending to the growth plate which may be centrally or, more commonly eccentrically placed

• A thin ‘egg-shell’ covering of expanded cortex is often identified

Mildly expansile lytic lesion with a thin sclerotic margin (arrows) located eccentrically within the proximal tibial metaphysis

Expansile lesion with a thin sclerotic margin (arrows) arising from the surface of the proximal ulna.

• Heterogeneous intermediate SI on T1W images with internal hypointense internal septa may be seen, which may enhance following administration of gadolinium contrast medium

• T2 or PDW images almost invariably demonstrate multiple FFLs

• Most important differential diagnosis of ABC is telangiectatic osteosarcoma.

• Between the ages of 5 and 15 years

• Presentation with pathological fracture is classical, especially with humeral lesions.

Location• Proximal humerus – most

common • Proximal femur – next

commonOther sites in adults• Calcaneus and • Posterior iiac blade

SIMPLE BONE CYST

Radiological Features• Initially, SBCs are located in the

proximal metaphysis of the humerus or femur and progress toward the diaphysis with skeletal growth, eventually reaching the middiaphysis

• Usually lies centrally in the shaft, expanding the bone symmetrically and thinning the cortex.

• The lesion is typically 6–8 cm in size.

• Apparent trabeculation is common, but periosteal reaction is not seen without fracture,

• Fracture may result in fragment of cortex penetrating the cyst lining, resulting in the fallen fragment sign

MRI• T1W images - low-to-intermediate

SI• Marked hyperintensity on T2W or

STIR images• These appearances are altered by

the presence of fracture, in which case haemorrhage may result in the presence of FFLs and pericystic oedema

Major differential diagnosis• ABC and• Fibrous dysplasia.

• Usually painless• Usually before the age of

30 years• Commonest sites –

monostotic FD – ribs, proximal femur , craniofacial bones

• FD may be associated with a variety of syndromes

• Portions of bone replaced by fibrous connective tissue and poorly formed trabecular bone

Monoostotic • 70 to 85%

Polyostotic• Invt of 2 bones

to more than 75% skeleton

FIBROUS DYSPLASIA

McCune–Albright’s syndrome –• Polyostotic FD (typically unilateral)• Ipsilateral café au lait spots and • Endocrine disturbance, most commonly

precocious puberty in girls

Mazabraud’s syndrome -• FD (most commonly polyostotic) and soft-tissue

myxomata.

Radiological Features• Geographic lesion that may

cause bone expansion and deformity with diffuse ground-glass matrix mineralisation

• A thick sclerotic margin (‘rind’ sign) is characteristic

• Varus deformity of the proximal femur (‘shepherd’s crook’ deformity) is a characteristic late finding.

• Skeletal scintigraphy is the best technique for identifying polyostotic disease

• CT beautifully demonstrates the ground-glass matrix

MRI - isointense on T1Wintermediate SI or hyperintense on T2W,

LANGERHANS CELL HISTIOCYTOSIS (LCH)• Spectrum of disorders characterised by the

idiopathic proliferation of histiocytes (Langerhans cells), which can involve virtually any organ and present either as focal/multifocal lesions

Three forms of the disease• Eosinophilic granuloma,• Letterer–Siwe disease• Hand–Schüller–Christian disease,

• Between the ages of 5 and 15 years

Location• Skull, pelvis, spine, mandible and

ribsRadiological Features• Long bone lesions are usually

located centrally within the diaphysis (~60%), followed by the metaphysis/ metadiaphysis

• Lesions are lytic, showing a fairly aggressive pattern of bone destruction with occasional reactive medullary sclerosis.

• A multi-laminated periosteal response is commonly seen, while endosteal scalloping and mild bone expansion are also features

Irregular lytic lesion (arrows) with a multi-laminatedperiosteal response

BONE ISLAND

• A bone island consists of well-differentiated mature bone tissue within the marrow

• Also referred to as enostosis• Usually it is seen as a coincidental finding.• In patients with breast- or prostate cancer a bone island can be

mistaken for an osteoblastic metastasis.• A bone island normally does not show increased uptake on a

bone scan

Small lytic lesion within the mid tibial diaphysis.

LANGERHANS-CELL HISTIOCYTOSIS

MAFUCCIS’S SYNDROME- HEMANGIOMA AND MULTIPLE ENCHONDROMATOSIS

OSTEOCHONDROMA

POLYOSTOTIC FIBROUS DYSPLASIA

• :TYPICAL GROUND GLASS APPEARANCE. significant expansion of the mid-diaphysis of the tibia and fibula, with the characteristic ground glass appearance tothe matrix of the fibrous dysplastic lesions.

ANEURYSMAL BONE CYST

• Expansile lytic lesion with a thin sclerotic margin located centrally in the metadiaphysis of distal left tibia and extending to the physis. There are subtle internal septations

ANEURYSMAL BONE CYST

SIMPLE BONE CYST

ENCHONDROMA

• Lytic geographic lesion with expansion and chondroid matrix (arrows) are seen on this radiograph of the proximal phalanx of the index finger.

• Distal femur readily shows the coarse dot-like, popcorn-like mineralization of chondroid matrix.