MSK: Lucent Lesions Flashcards
How can you tell the age of a pt on radiographs?
- Open growth plates (pediatric pt)
- Degenerative changes (pt likely over 40)
Differential for epiphyseal (or epiphyseal equivalent) lytic lesions
- Giant cell tumor
- Chondroblatoma
- Infection
- Clear cell chondrosarcoma
Note: Aneurysmal bone cysts can also involve the epiphysis (if the growth plates are closed), but they usually start in the metaphysis.
Malignant epiphyseal Lucent lesion…
Clear cell chondrosarcoma
What are the epiphyseal equivalents?
- Carpal bones
- Patella
- Calcaneus
- Apohyses (greater trochanter, lesser trochanter, tuberosities, etc.)
Note: Lesions here will also get the epiphyseal lesion differential.
What is the fastest growing area of bone?
The metaphysis
Which area of bone has the most blood supply?
The metaphysis
Note: This is why metastases and infection are common here.
Fibrous dysplasia
A skeletal developmental anomaly of osteoblasts (failure of normal maturation and differentiation) that results in replacement of the normal medullary space
What is the classic imaging feature of fibrous dysplasia?
Ground glass appearance of the bony matrix (without any periosteal reaction or pain)
Note: It can look like anything though with lytic, mixed, and plastic phases).
What are the most common locations for fibrous dysplasia?
Ribs and long bones
If there is fibrous dysplasia of the pelvis, what other area is usually involved?
The ipsilateral femur (often with the Shepherd Crook deformity)
When does fibrous dysplasia tend to develop?
Monostotic: 20s and 30s
Polyostotic: <10 y/o (usually associated with genetic syndromes)
Shephard Crook deformity (coxa vara angulation)
Differential for Shephard Crook deformity
- Fibrous dysplasia (classically)
- Paget
- Osteogenesis imperfecta
Polyostotic fibrous dysplasia is associated with…
- McCune Albright syndrome (young females with precocious puberty and cafe au lait spots)
- Mazabraud syndrome (middle aged females with soft tissue myxomas and increased risk for malignant transformation)
Adamantinoma
A mixed lytic and sclerotic tibial lesion that resembles fibrous dysplasia, but is potentially malignant (very rare)
Think non ossifying fibroma/fibrous cortical defect
Note: Chondromyxoid fibroma can also look like this, but is much more rare.
Treatment for non ossifying fibroma
Nothing (they typically become more sclerotic and then regress)
What is the most common location for a non ossifying fibroma/fibrous cortical defect?
Around the knee
What is the most common location for a non ossifying fibroma/fibrous cortical defect?
Around the knee
Where are non ossifying fibromas/fibrous cortical defects usually located within a bone?
Metaphyses (eccentrically located)
Note: They usually appear in the metaphysis near the physis, but then get progressively farther from the physis as the pt grows.
How can you differentiate a nonossifyinng fibroma/fibrous cortical defect from a giant cell tumor?
NOF/FCD should have a sclerotic border
GCTs don’t have a sclerotic border
Nonossifying fibromas/fibrous cortical defects are associated with…
Neurofibromatosis 1
What is the difference between a nonossifying fibroma and a fibrous cortical defect?
Size:
If < 3 cm, it is a fibrous cortical defect
If > 3 cm, it is a nonossifying fibroma
Note: Fibroxanthoma is an umbrella term that includes both.
Jaffe-Campanacci syndrome
- Multiple nonossifying fibromas
- Cafe au lait spots
- Mental retardation
- Hypogonadism
- Cardiac malformations
Note: These pts are at high risk for pathologic fractures.
Enchondroma
A hyaline cartilage tumor of the medullary cavity
What age group is enchondroma more common in?
10-30 y/o
Think enchondroma
Note: Chondroid matrix is usually visible when these are in the long bones (e.g. femur, humerus).
Think enchondroma
Note: These usually appear lytic in the fingers/toes.
What is the most common cystic lesion in the hands and feet?
Enchondroma
Do enchondromas typically have a periosteal reaction?
No, enchondromas are not associated with a periosteal reaction
Enchondroma with history of pain…
Think low grade chondrosarcoma
Enchondroma that is > 4-5 cm…
Think low grade chondrosarcoma
Enchondroma with a chondroid matrix that changes over time…
Think low grade chondrosarcoma
What syndromes are associated with multiple enchondromas?
- Ollier disease
- Maffucci syndrome (also will have hemangiomas)
Note: Both have an increased risk of chondrosarcoma, but Maffucci has a higher risk (“Maffucci has More”).
Multiple enchondromas and multiple hemangiomas…
Think Maffucci syndrome
Note: These pts are at increased risk for chondrosarcoma.
What is the usual age for eosinophilic granuloma?
< 30 y/o
Vertebra plana
Differential for vertebra plana
MELT:
- Mets/Myeloma
- Eosinophilic granuloma (Langerhans cell histiocytosis)
- Lymphoma
- Trauma/Tubercuosis
7 y/o
Think Langerhanscell histiocytosis (most common cause of vertebra plana in a children)
Note: When there is a single skeletal lesion, it is onften referred to as an eosinophilic granuloma.
Eosinophilic granuloma
Note: Beveled edge lytic skull lesion.
What is the classic appearance of eosinophilic granuloma?
Highly variable and can look like everything (lytic, blastic, +/- sclerotic border, +/- periosteal reaction, +/- osseous sequestrum)
Note: Its usually included in the differential for any bone bone lesion in pts under 30.
Differential diagnosis for an osseous sequestrum
- Osteomyelitis
- Lymphoma
- Fibrosarcoma
- Eosinophilic granuloma
Note: Osteoid osteoma can also mimic a sequestrum.
What features must be present for you to consider a giant cell tumor?
- Physis must be closed
- No sclerotic border
- Lesion must abut the articular surface
Could this be a giant cell tumor metastasis?
Yes (5% of GCTs have pulmonary metastases)
Note: GCTs are considered quasi-malignant (they can be locally invasive and can have pulmonary metastases). The disease is still curable with resection of the pulmonary mets.
Treatment for giant cell tumor pulmonary mets
Wide margin resection (curable)
What is the most common location for a giant cell tumor?
The knee (abutting an articular surface)
What is the most common age for a giant cell tumor?
20-30
Note: The physes must be closed.
Giant cell tumors can turn into…
Aneurysmal bone cysts
Think giant cell tumor
Note: Well-defined lesion without a sclerotic border that abuts the articular surface in a pt with closed physes.
Bone pain at night that is relieved with aspirin…
Think osteoid osteoma
What is the typical pt age for an osteoid osteoma?
Adolescent (10-25 y/o)
Classic appearance of an osteoid osteoma
Lucent nidus surrounded by dense sclerotic cortical bone
What are the most common locations for an osteoid osteoma?
- Metaphysis/diaphysis of long bones (especially the femoral neck)
- Posterior elements of the spine
- Fingers
Painful scoliosis…
Think osteoid osteoma
What is the classic MRI appearance of an osteoid osteoma?
Severe edema out of proportion to the size of the lesion +/- adjacent soft tissue edema
Think osteoid osteoma
Note: This is the “double density sign” (very intense central nidus with less intense surrounding reactive bone).
Think osteoid osteoma
Painful scoliosis is often due to an osteoid osteoma. Which direction does the scoliosis point?
The convexity of the scoliosis points away from the osteoid osteoma
Treatment for osteoid osteoma
Percutaneous radio frequency ablation
Contraindication for radio frequency ablation of an osteoid osteoma
Lesion is within 1 cm of a nerve or other vital structure (usually avoided in hands, spine, and pregnant pts)
What growth deformities can occur if there is an osteoid osteoma?
Increased length and girth of bones
What joint complications can occur in the setting of an osteoid osteoma?
- Synovitis (if intraarticular)
- Arthritis (due to primary synovitis or from altered joint mechanics)
What is the difference between an osteoid osteoma and an a osteoblastoma?
Size:
If less than 2 cm -> osteoid osteoma
If greater than 2 cm -> osteoblastoma
Osteoblastoma is most commonly seen in what pt age?
<30 y/o
Note: It’s basically an osteoid osteoma that is too large.
What is the most common location for an osteoblastoma?
- Posterior elements of the spine
- Long bones (usually diaphysis)
Differential for a lucent bone lesion in the posterior elements of the spine
- Osteoblastoma
- Aneurysmal bone cyst
- Metastases
What is the common pt age for aneurysmal bone cysts?
Less than 30 y/o
What are the most common locations for an aneurysmal bone cyst?
- Tibia (most common)
- Vertebral body (2nd)
- Femur (3rd)
- Humerus (4th)
Aneurysmal bone cyst
Aneurysmal bone lesions with thin-walled, blood-filled spaces that may develop after trauma
What are the two major types of aneurysmal bone cysts?
- Primary
- Secondary (associated with another tumor, such as a giant cell tumor)
40% of secondary aneurysmal bone cysts are associated with…
Giant cell tumors
Most likely diagnosis
Aneurysmal bone cyst
Solitary (unicameral) bone cysts are most often seen in what age group?
Pts under 30 y/o
What is the most common location for a solitary (unicameral) bone cyst?
Tubular bones (90-95%), usually the humerus or femur
What is the main unique feature always seen in a solitary (unicameral) bone cyst?
They are always located centrally within the bone
Fallen fragment sign…
Solitary (unicameral) bone cyst
Solitary (unicameral) bone cyst
Note: Fallen fragment sign (arrow) is a bone fragment in the dependent portion of a lucent bone lesion. This is pathognomonic.
Think solitary (unicameral) bone cyst
Note: This could also be an intraosseous lipoma, but these tend to contain dystrophic calcifications.
Pt with hyperthyroidism
Think brown tumor (focal accumulations of giant cells and fibrous tissue that can be seen in the setting of hyperparathyroidism)
Hyperparathyroidism
Subperiosteal resorption, which can be seen in hyperparathyroidism
Hyperparathyroidism
Clavicular subchondral bone resorption with irregular feathery articular surface, which can be seen in hyperparathyroidism
Subperiosteal bone resorption, which can be seen in hyperparathyroidism
Note: Subperiosteal resorption of the radial aspect of the middle phalanges of the second and third fingers (white arrows); feathery appearance and early tufts resorption-acroosteolysis (red arrows).
Black arrow
Brown tumor
Note: Subperiosteal bone resorption (red arrows), suggesting hyperparathyroidism. There is also intracortical and trabecular resorption.
Brown tumor (black arrow) with pathologic fracture (yellow arrow)
Note: Subperiosteal bone resorption suggesting hyperparathyroidism.
What are the classic locations for subperiosteal bone resorption in hyperparathyroidism?
- Fingers
- Edge of clavicle
- Inferior surface of ribs
What is the typical age group for chondroblastoma?
Ages 5-25 (90%)
Think chondroblastoma
Note: Epiphyseal lucent lesion in a pt with open physes.
What is the typical location of a chondroblastoma within a bone?
Chondroblastomas are located in the epiphysis (or an epiphyseal equivalent)
Is recurrence common following resection of a chondroblastoma?
Yes (30% of cases recur)
20 y/o
Think chondroblastoma
Note: Epiphyseal lesion in a young pt.
What is the most common location of a proximal femoral chondroblastoma?
The greater trochanter (an epiphyseal equivalent rather than the actual proximal femoral epiphysis)
Differential for an intertrochanteric lucent lesion in the femur
- Lipoma
- Solitary bone cyst
- Monostotic fibrous dysplasia
- Liposclerosing myxofibroma
Where are the epiphyseal equivalents in the calcaneus?
Green areas are epiphyseal equivalents
Differential for lucent lesion in the calcaneus
Classic location for a chondroblastoma in the calcaneus
Superior calcaneal epiphysis (but can occur at any of the 3 calcaneal epiphyses)
Classic location for a giant cell tumor in the calcaneus
Posterior metaphyses/epiphysis
Classic location for an osteoid osteoma in the calcaneus
Superior calcaneal epiphysis
Classic location for metastases to the calcaneus
Posterior metaphyseal region (most blood supply)
Classic location for a solitary bone cyst in the calcaneus
Anterior 1/3 of calcaneus on the lateral side
Classic location for a calcaneal intraosseous lipoma
Anterior 1/3 of calcaneus on the lateral side
Intraosseous lipoma
Note: The central density is due to fat necrosis (occurs in ~50% of cases).
Think calcaneal pseudocyst
Note: Triangular appearance and persistence of thin trabeculae can be helpful.
Which bone metastases are classically blastic?
- Prostate
- Carcinoid
- Medulloblastoma
Which bone metastases are predominantly lytic?
- Renal cell cancer
- Thyroid
- Melanoma
- Multiple myeloma
- Non-small cell lung cancer
- Non-hodgkin lymphoma
Next step: You aren’t sure if a sclerotic lesion is a bone island or a prostate met
Compare to priors if available, if not then get a bone scan (only the prostate met will have uptake)
What is the typical age range for multiple myeloma?
40s-80s
Lytic vertebral lesions that destroy the vertebral body, but spare the posterior elements…
Think multiple myeloma
Next step: Pt with multiple myeloma
Get a skeletal survey or MRI (MRI is most sensitive)
Note: Bone scans are often negative for multiple myeloma (which produces lytic lesion).
Is multiple myeloma in the differential?
Yes, 15-25% of pts with multiple myeloma present with diffuse osteopenia rather than focal lytic lesions
What age is typical for a plasmacytoma?
Under age 40
Plasmacytoma
A discrete solitary mass of neoplastic monoclonal plasma cells that can occur in a bone or in soft tissues (extramedullary subtype)
Note: It can be considered a focal form of multiple myeloma.
Plasmacytoma
Note: This is the “mini brain” appearance that can occur in vertebral bodies.
POEMS
A rare medical syndrome consisting of plasma cell proliferation (usually multiple myeloma), neuropathy, and organomegaly
Note: Radiographically it appears similar to multiple myeloma, but with sclerotic metastases.
Long lesion in a long bone…
Think fibrous dysplasia
Lytic lesion with a hazy matrix…
Think fibrous dysplasia
Note: This is another way to say ground glass.
Chondroid matrix lesion in the proximal humerus or distal femur…
Think enchondroma
Lucent lesion in the finger or toe…
Think enchondroma
Epiphyseal tibial lesion in a teenager…
Think chondroblastoma
Lucent lesion in the greater trochanter…
Think chondroblastoma
Lucent lesion with dependent fragment in the humerus…
Solitary bone cyst
Calcaneal lesion with central calcification…
Intraosseous lipoma
Lucent lesion in the skull of a young pt…
Think eosinophilic granuloma (the mildest form of Langerhans cell histiocytosis)
Vertebra plana in a kid…
Think eosinophilic granuloma
Vertebra plana in an adult…
Think metastasis (also myeloma)
Lucent nidus in the tibia/fibula…
Think osteoid osteoma
Calcified lesion in a posterior element of the C spine…
Think osteoblastoma
Multiple sclerotic lesions centered around a joint…
Think osteopoikolosis
Multiple lucent bone lesions in a pt over 40…
Think metastases, multiple myeloma, or non-Hodgkin lymphoma
Chondral lesion in a long bone measuring 1-2 cm…
Think enchondroma
Chondral lesion in a long bone measuring >4-5 cm…
Think low-grade chondrosarcoma
Well-defined lytic lesion measuring <3 cm in the cortex of a long bone with a sclerotic rim…
Think fibrous cortical defect
Well-defined lytic lesion measuring >3 cm in the cortex of a long bone with a sclerotic rim…
Think nonossifying fibroma
Sclerotic lesion with central lucent nidus measuring < 2 cm…
Think osteoid osteoma
Sclerotic lesion with central lucent nidus measuring > 2 cm…
Think osteoblastoma
