Bones Flashcards
generalised increased bone density 12
Most common
1. Metastases—prostate and breast most common. Heterogeneous;
generally not diffuse.
2. Sickle cell disease—medullary sclerosis and bone infarcts. Growth
arrest of long bones. H-shaped vertebrae.
3. Myelofibrosis—older patients. Diffuse medullary sclerosis, loss of
corticomedullary differentiation. No heterogeneity
Less common
4. Renal osteodystrophy—axial > appendicular. Rugger jersey spine.
5. Osteopetrosis—thickened cortices with reduced marrow space.
Pathological transverse fractures.
6. Paget’s disease—coarse trabeculae and bone expansion. Multiple
bones rather than generalized.
7. Systemic mastocytosis—lytic, sclerotic or mixed. Usually diffuse
affecting spine and epiphyses of long bones.
Rare
8. Fluorosis—diffuse osteosclerosis, particularly ribs and spine, with
entheseal ossification.
9. Pyknodysostosis—narrow medullary cavities with multiple long
bone fractures.
10. Hypoparathyroidism—diffuse sclerosis in 10%. Dense
metaphyseal bands and skull vault thickening.
11. Progressive diaphyseal dysplasia (Camurati-Engelmann
disease)—young patients. Fusiform enlargement and sclerosis of
long bones sparing the epiphyses.
12. Myeloma—rare osteosclerosing form. Associated with POEMS
syndrome ( Polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy myeloma, and skin changes)
SOLITARY SCLEROTIC BONE LESION
15 (5-10)
Most common
1. Bone island (enostosis)—ovoid with long axis parallel to long axis
of bone and a feathered border.
2. Enchondroma—confluent punctate or nodular calcification, denser
centrally than peripherally. Enchondromas in the large long bones
are often more calcified than those in the fingers.
3. Metastasis—prostate, breast, mucinous adenocarcinoma of GI
tract, carcinoid, lymphoma, TCC in adults. Medulloblastoma and
neuroblastoma in children.
4. Callus—usually associated with a fusiform swelling in long bones.
5. Bone infarct—usually a central metadiaphyseal lucency with thin
serpentine calcified margins.
Less common
6. Paget’s disease—blastic phase causes sclerosis accompanied by
bone expansion, and cortical and trabecular thickening.
7. Osteoma—arises from membranous bone: skull and paranasal
sinuses. Ivory osteomas contain no trabeculae. Mature osteomas
have visible marrow. If multiple consider Gardner syndrome.
8. Osteoid osteoma/osteoblastoma—sclerosis caused by eccentric
periosteal thickening. Osteoid osteoma: radiolucent nidus <2 cm.
Osteoblastoma: more common in the posterior elements of
spine, larger nidus with thin shell.
9. Healed or healing bone lesion—treated metastasis, NOF, simple
bone cyst, brown tumour, eosinophilic granuloma.
10. Primary bone sarcoma—aggressive features: poorly defined
margins, aggressive periosteal reaction, Codman’s triangles, bone
destruction, soft tissue mass.
11. Fibrous dysplasia—usually lytic with ground glass areas but can
calcify in later life.
12. Chronic osteomyelitis—usually associated with an area of lysis,
chronic periosteal reaction and occasionally a sequestrum.
13. Chronic recurrent multifocal osteomyelitis (CRMO)—idiopathic
inflammatory disorder. Most commonly affects clavicles and tibias
in children. Often multifocal.
14. Lymphoma—primary bone lymphoma rare. More common as
secondary involvement. Large extraosseous soft tissue mass with
relative preservation of bone.
15. Cement and bone graft substitutes—history of surgery
MULTIPLE SCLEROTIC BONE LESIONS
Most common
1. Metastases—prostate, breast, mucinous adenocarcinoma of GI
tract, carcinoid, lymphoma, TCC in adults. Medulloblastoma and neuroblastoma in children.
2. Multiple healed bone lesions—lytic metastases following
radiotherapy or chemotherapy. Eosinophilic granulomas and brown tumours following treatment.
3. Paget’s disease—often polyostotic.
Less common
- Multiple bone infarcts—consider an underlying disorder, e.g.
sickle cell or Gaucher disease. - Multiple stress fractures—callus formation around fractures.
- Lymphoma.
- Osteopoikilosis—multiple symmetrically distributed bone islands
in the metaphyses and epiphyses of long bones and the pelvis.
Some ovoid, some round. - Multifocal osteosarcoma.
- Multiple osteomas—Gardner syndrome.
- Fibrous dysplasia—long lesions in long bones, often hemimelic
(McCune-Albright syndrome). Usually lytic but can calcify. - CRMO and SAPHO.
Rare
- Osteopathia striata (Voorhoeve disease)—linear striations along
long axis of long bone. - Erdheim-Chester disease—bilateral symmetrical metadiaphyseal
sclerosis in long bones, most commonly femora and tibias. - Multiple myeloma—sclerotic in 3%.
- Tuberous sclerosis.
- Intramedullary osteosclerosis—diaphyseal endosteal sclerosis
typically involving the tibia or femur, usually bilateral and in women.
BONE SCLEROSIS WITH A PERIOSTEAL REACTION 13
Most common 5
Less 6
Rare 2
Most common
- Healing fracture.
- Metastasis—osteoblastic metastases from prostate.
- Osteoid osteoma/osteoblastoma—solid or lamellated periosteal reaction.
- Chronic osteomyelitis—look for sequestrum.
- Osteosarcoma—classically sunray spiculation.
Less common
- Ewing sarcoma—often onion-skin or lamellated periosteal reaction.
- Chondrosarcoma—chondroid matrix with regions of enchondral
ossification. - Lymphoma.
- CRMO—clavicles and tibias in children and adolescents.
- SAPHO syndrome (synovitis–acne–pustulosis–hyperostosis–osteitis)—similar to CRMO but in adults. Although similar long bone changes may be seen, anterior chest wall and pelvic involvement predominate.
- Infantile cortical hyperostosis (Caffey’s disease)—infants <6
months of age. Multiple bones, especially mandible, ribs and clavicles.
Rare
- Melorheostosis—sclerotomal distribution(The sclerotome forms the vertebrae and the rib cartilage and part of the occipital bone). Cortical and medullary sclerosis likened to dripping candle wax.
- Tertiary syphilis—usually bilateral periostitis involving skull, clavicles, ribs and tibias. Mixed sclerotic and lytic ‘gummatous’ lesions can also be seen.
SOLITARY SCLEROTIC BONE LESION WITH A LUCENT CENTRE 9 MC 4 Less 3 Rare 2
Most common
- Osteoid osteoma/osteoblastoma—lucent nidus.
- Brodie’s abscess.
- Medullary bone infarct—irregular serpentine outline.
- Stress fracture—lucent fracture line may be visible.
Less common
5. Looser’s zone of osteomalacia.
6. Liposclerosing myxofibrous tumour—characteristic location in
the intertrochanteric region of the femur.
7. Tuberculosis.
Rare
- Syphilis.
- Yaws. (is a chronic skin infection characterized by papillomas (noncancerous lumps) and ulcers. It is caused by the bacterium Treponema pallidum subspecies pertenue)
COARSE TRABECULAR PATTERN
6
- Paget’s disease.
- Osteoporosis.
- Osteomalacia.
- Haemoglobinopathies.
- Haemangioma.
- Gaucher disease
SKELETAL METASTASES
Lytic 5
- Lung.
- Breast—usually lytic but can be sclerotic or mixed.
- Myeloma.
- Nonmucinous adenocarcinomas of the GI tract.
- Most other primary sources
SKELETAL METASTASES
Lytic and expansile
- Renal cell carcinoma.
- Thyroid.
- Hepatocellular carcinoma.
- Melanoma.
- Phaeochromocytoma
SKELETAL METASTASES
Sclerotic 7
- Prostate.
- Breast—particularly post treatment.
- Carcinoid.
- Mucinous adenocarcinomas of the GI tract.
- Transitional cell carcinoma.
- Small cell lung cancer.
- Lymphoma—particularly Hodgkin lymphoma; rare.
SKELETAL METASTASES
Mixed 8
- Breast.
- Lung.
- Lymphoma.
- Cervix.
- Testis.
- Transitional cell carcinoma.
- Melanoma.
- Neuroblastoma—in children
LUCENT BONE LESIONS
Well-defined, sclerotic margin
12
- Nonossifying fibroma—young patients, eccentric metaphyseal
location. Consider benign fibrous histiocytoma if patient >25
years or atypical location. - Bone cysts—both SBCs and ABCs usually have a thin sclerotic
margin. ABCs are more eccentric and expansile. - Fibrous dysplasia—variable appearance, typically diaphyseal.
- Chondroblastoma—epiphyseal location, young patients. If
patient >20 years, consider clear cell chondrosarcoma. - Brodie’s abscess—typically young patients, most common in
metaphysis. Discrete lucency with surrounding ill-defined
sclerosis. - Healing metastases or primary malignant bone
lesions—sclerotic rim indicates a good response to treatment. - Osteoblastoma—large lucent nidus with a sclerotic margin. Most
common in spine. - Intraosseous lipoma—typically in calcaneus or intertrochanteric
region of femur. Thin sclerotic margin. Focus of central
calcification is pathognomonic but not always present. - Liposclerosing myxofibrous tumour—characteristic location:
intertrochanteric region of femur. Usually a thick sclerotic margin. - Adamantinoma/osteofibrous dysplasia (OFD)—characteristic
location: anterior cortex of tibial diaphysis. Both can look
identical but OFD occurs in a younger age group (<10 years). - Chondromyxoid fibroma—rare; can mimic NOF, BFH and ABC.
- Haemophilic pseudotumour—usually very expansile + other
signs of haemophilia
LUCENT BONE LESIONS
Well-defined, nonsclerotic margin
9
- Metastasis—usually older patients, in axial or proximal
appendicular skeleton. - Myeloma/plasmacytoma—older patients, usually in axial or
proximal appendicular skeleton. Typically ‘punched-out’
appearance, may be expansile. - Low-grade chondral lesions—e.g. enchondroma, low-grade
chondrosarcoma. Both can be lytic without chondroid matrix. - Giant cell tumour—typically has a well-defined nonsclerotic
margin. Adults 20–50 years. - Simple/aneurysmal bone cyst—both may have no perceptible
sclerotic margin. - Eosinophilic granuloma—may appear well-defined.
- Brown tumour—often expansile. Look for other signs of
hyperparathyroidism. - Lytic phase of Paget’s disease—well-defined flame-shaped
advancing edge without sclerosis. - Desmoplastic fibroma—rare. Often contains pseudotrabeculations
LUCENT BONE LESIONS
Poorly defined margin
- Metastasis—usually ill-defined.
- Myeloma—usually discrete but may appear ill-defined.
- Osteomyelitis—ill-defined and lytic in the acute phase.
- Bone lymphoma—typically ill-defined subtle bone destruction
with a large soft tissue mass. Can occur at any age but more
common in older patients. - Primary bone sarcomas—e.g. Ewing sarcoma, osteosarcoma,
chondrosarcoma, fibrosarcoma, undifferentiated pleomorphic
sarcoma, angiosarcoma. Internal matrix may be absent. - Eosinophilic granuloma—patients <30 years. Can occur
anywhere, often has an aggressive appearance indistinguishable
from infection or malignancy. - Giant cell tumour—can appear ill-defined. Adults 20–50 years
GROSSLY EXPANSILE LUCENT
BONE LESION 12
Most common
- Plasmacytoma—older patients, usually in axial or proximal appendicular skeleton.
- Metastases—RCC, thyroid, HCC, phaeochromocytoma, melanoma. Usually in axial or proximal appendicular skeleton.
- Aneurysmal bone cyst—in children and young adults. Usually has a thin sclerotic margin.
- Giant cell tumour—usually older patients than ABC. Often abuts articular surface, no sclerotic margin.
Less common
5. Telangiectatic osteosarcoma—mimics ABC.
6. Fibrous dysplasia—usually fusiform expansion rather than a
discrete expansile mass.
7. Brown tumour—look for other signs of hyperparathyroidism.
8. Haemangioma—often expansile when in flat bones, e.g. skull or
pelvis, with a sunburst periosteal reaction.
9. Chordoma—in sacrum, clivus or vertebral bodies.
Rare
- Haemophilic pseudotumour—look for other signs of haemophilia.
- Slow growing central bone sarcoma.
- Hydatid cyst
LUCENT EPIPHYSEAL BONE LESION 7
This includes carpal and tarsal bones since they are epiphyseal
equivalents.
1. Lesions related to joint pathology—e.g. geode, intraosseous
ganglion, erosion, osteochondral defect, PVNS.
2. Giant cell tumour—nonsclerotic margin, extends from metaphysis
to epiphysis. Mainly in adults.
3. Chondroblastoma—perilesional sclerosis ± chondroid calcification.
Typically 10–20 years.
4. Infection—including Brodie’s abscess.
5. Clear cell chondrosarcoma—mimics chondroblastoma but usually
occurs >20 years.
6. Location-specific lesions—e.g. intraosseous lipoma (calcaneus,
central calcification), simple bone cyst (calcaneus, no central
calcification), osteoblastoma (talus).
7. Bone lesions which can occur anywhere—e.g. metastasis, brown
tumour, lymphoma, myeloma, haemophilic pseudotumour
LUCENT BONE LESION CONTAINING
CALCIUM OR BONE 14
MC 4
LC 10
Most common
1. Enchondroma—chondroid matrix.
2. Osteoid osteoma and osteoblastoma—lucent nidus can contain
calcification.
3. Avascular necrosis and bone infarction.
4. Metastases—some are mixed lytic and sclerotic.
Less common
5. Chondroblastoma—chondroid matrix. Epiphyseal location.
6. Chondrosarcoma—chondroid matrix. Usually metaphyseal.
7. Osteosarcoma—osteoid matrix. Usually metaphyseal.
8. Fibrous dysplasia—usually ground-glass density but can be sclerotic.
9. Osteomyelitis with sequestrum.
10. Eosinophilic granuloma—‘button sequestrum’ (central density with surrounding lucency)
11. Intraosseous lipoma—characteristic central focus of calcification,
especially in calcaneus.
12. Haemangioma—contains coarsened trabeculae. Most common
in spine.
13. Liposclerosing myxofibrous tumour—classically intertrochanteric
region of femur.
14. Fibrosarcoma/undifferentiated pleomorphic sarcoma.
EXOPHYTIC AND JUXTACORTICAL
BONE LESIONS
8
- Callus—can be profuse, e.g. after an avulsion fracture, if bones
misaligned or in malunion. - Osteochondroma—well-defined exophytic bony mass (sessile or
pedunculated), usually arising from metaphysis and pointing away from the joint. The cortex and trabeculae within the lesion should be continuous with those in the metaphysis. Can transform to chondrosarcoma: worrying features include continued growth or change in morphology after physeal
closure, bone destruction, soft tissue mass and cartilage cap >1 cm thick (on ultrasound/MRI). - Heterotopic ossification and myositis ossificans—well-defined with dense ossification in the periphery and less density centrally. May mimic surface osteosarcoma in the early stage; follow up can help differentiate by showing maturation of ossification.
- Surface osteosarcoma—three types:
(a) Parosteal—low grade, arises from outer periosteum, usually metaphyseal. Pedunculated ‘cauliflower’ appearance with a narrow stalk + partial cleft between the mass and underlying bone. Mature osteoid matrix within the mass which is more dense centrally (in contrast to myositis ossificans).
(b) Periosteal—intermediate grade, arises from inner periosteum, usually diaphyseal. Broad-based with cortical erosion and spiculated periosteal reaction. Less organized osteoid matrix.
(c) High grade—amorphous osteoid matrix + larger soft tissue
mass ± underlying cortical destruction. Usually diaphyseal. - Periosteal chondroma/chondrosarcoma—both typically arise on
the metaphyseal surface as a soft tissue mass ± chondroid matrix.
The underlying cortex is mildly scalloped. Difficult to differentiate
the two on imaging; size >3 cm is more suggestive of
chondrosarcoma. - Cortical desmoid—characteristic location: distal posteromedial
femoral metaphyseal cortex (at muscle insertion site).
Well-defined scalloping of cortical surface, typically small. - Parosteal lipoma—juxtacortical radiolucent mass with an
associated irregular bony excrescence arising perpendicularly
from the periosteum. Characteristic bony spur at base. - Bizarre parosteal osteochondromatous proliferation (BPOP)—
typically arises from the periosteum of bones in the hands
‘MOTH-EATEN BONE’ IN AN ADULT
8
- Metastases.
- Multiple myeloma—numerous punched-out lytic lesions.
- Bone sarcomas—e.g. Ewing sarcoma, osteosarcoma,
chondrosarcoma. - Bone lymphoma—subtle ill-defined bone destruction, usually with
a large soft tissue mass. - Langerhans cell histiocytosis—young adults only.
- Osteomyelitis.
- Osteoporosis—extensive cortical tunnelling can mimic an
aggressive process. - Hyperparathyroidism—extensive subperiosteal bone resorption +
brown tumours can mimic malignancy
